WO2007117092A1

WO2007117092A1 - Skateboard

Info

Publication number: WO2007117092A1
Application number: PCT/KR2007/001604
Authority: WO
Inventors: Dong-Pyo Cho
Original assignee: Dong-Pyo Cho
Priority date: 2006-04-11
Filing date: 2007-04-02
Publication date: 2007-10-18

Abstract

A skateboard is disclosed. The skateboard includes a rear deck, a front deck which is longer than the rear deck, a front truck and a rear truck which are mounted underneath the front deck and the rear deck, front sliding units and rear sliding units which are mounted to the front truck and the rear truck, a crossbar which is coupled to the front and rear trucks, the crossbar being bent by external force for shaking the rear deck leftward and rightward and being restored to an original shape when the external force is removed, a slider which is mounted to the crossbar below the front deck, the slider performing sliding motion on a lower surface of the front deck as the crossbar is bent, and a middle sliding unit which is horizontally turnably mounted to the slider and performs sliding motion together with the front and rear sliding units.

Description

Description SKATEBOARD

Technical Field

[1] The present invention relates to a skateboard which is one of the sports instruments for use in skating, and more particularly, to a skateboard that includes separate front and rear decks, each of which a foot is put on. Background Art

[2] Fig. 1 is a plan view illustrating a conventional skateboard.

[3] As shown in Fig. 1, the conventional skateboard includes a front deck Ia, a rear deck Ib which is separated from the front deck Ia, trucks 2a and 2b which are respectively mounted underneath the front deck Ia and the rear deck Ib, sliding units 3a and 3b which are respectively mounted to the trucks 2a and 2b in pairs, and a crossbar 4, both ends of which are horizontally rotatably connected to a rear portion of the front deck Ia and a front portion of the rear deck Ib. Each of the sliding units 3a and 3b is configured as a wheel. The wheels mounted to the rear deck Ib can be turned to the left and right. Non-described reference numerals 5a and 5b refer to hinges.

[4] In the skateboard including the separate front and rear decks (hereinafter, referred to as a deck-separating type skateboard), when a rider puts feet respectively on the front deck Ia and the rear deck Ib and shakes the rear deck Ib leftward and rightward around the hinge 5a of the front deck Ia as shown in Fig. 2, the skateboard propels forward (in the F direction) by propulsive power due to reaction generated in the above shaking process.

[5] Accordingly, the deck-separating type skateboard can slide at a speed higher than another type of skateboard which includes a deck formed in a unitary body (hereinafter, referred to as a unitary deck type skateboard) and propels by propulsive power generated by putting one foot on the deck and pushing the ground with another foot.

[6] As shown in Fig. 3, the deck-separating type skateboard is turned to the left (or right) when the feet of the rider are toed-out (or toed-in) so that the front deck Ia is turned to the left (or right) and the rear deck Ib is turned to right (or left). In the turning operation, if the rider shifts the center of gravity to the left (or right), the skating direction of the skateboard can be changed more effectively and stably. Further, the skating direction of the skateboard can be changed by just turning any one of the front deck Ia and the rear deck Ib (not necessarily turning both the front deck Ia and the rear deck Ib). Therefore, the deck-separating type skateboard can decrease a turning radius and achieve steep turn more freely, when compared to the unitary deck type skateboard whose skating direction is changed only by shifting the center of gravity of the rider to the left and right.

[7] However, the above conventional deck-separating type skateboard has the following problems.

[8] First, when shaking the rear deck Ib leftward and rightward to generate the propulsive power, the power necessary for shaking the rear deck Ib totally depends on the rider s force. Accordingly, the physical strength of the rider is consumed fast. Further, because there is a limit in increasing the skating speed, the rider s desire for dynamic skating, e.g., the desire of skating at a higher speed or accelerating the speed more rapidly, cannot be satisfied.

[9] Second, because the upper surfaces of the decks are flat, when shaking the rear deck

Ib leftward and rightward or turning the front deck Ia and the rear deck Ib to change the skating direction, the rider s feet frequently slip on the decks and drop therefrom.

[10] This problem may be prevented to a certain extent by attaching a grip tape, which is configured as sandpaper, to the upper surfaces of the decks to mitigate the slip of the feet. But, the attachment of the grip tape cannot obtain the satisfactory results. Alternatively, binders for binding the feet are mounted to the decks to solve the above problem. But, because the feet cannot be separated from the decks when falling down during skating, the rider, especially the beginner, is easily injured.

[11] Third, because the sliding units 3a and 3b are configured as the wheels, the rider can skate on the ground, but cannot skate on the ice.

[12] Finally, because the wheels are simply mounted to the trucks 2a and 2b, shock generated from the road surface, especially when skating on an uneven road, is directly transferred to the decks or the rider, thereby deteriorating the steerability and skating stability.

Disclosure of Invention

Technical Problem

[13] Therefore, the present invention has been made in view of the above problems, and it is an object of the present invention to provide a skateboard that is equipped with an elastic crossbar which is also bent leftward and rightward when shaking a rear deck leftward and rightward, thereby more easily acquiring propulsive power by using elastic restoring force of the crossbar; that is constituted such that both ends of the crossbar are respectively coupled to a truck of the front deck and a truck of the rear deck to enlarge an extent that the crossbar is bent, thereby acquiring strong propulsive power; and that is constituted such that the front deck extends lengthwise to narrow a gap between the front deck and the rear deck and a sliding unit is additionally mounted to the crossbar below the front deck, thereby preventing the crossbar from being bent downward and causing collapse of the front deck or the rear deck, and increasing skating stability due to the sliding unit being turned according to the left and right bending of the crossbar.

[14] It is another object of the present invention to provide a skateboard that is capable of preventing rider s feet from slipping outwardly from the front and rear decks by forming protruding portions on outward portions of the front and rear decks.

[15] It is a further object of the present invention to provide a skateboard that is equipped with sliding units which are configured as wheels or blades, thereby enabling a rider to skate on the ice as well as the ground.

[16] It is yet another object of the present invention to provide a skateboard that is equipped with a shock-absorbing device, thereby preventing shock from the road surface or the ice surface from being directly transferred to the decks or a rider. Technical Solution

[17] In accordance with an aspect of the present invention, the above and other objects can be accomplished by the provision of a skateboard comprising: a rear deck; a front deck which is formed to have a length longer than the rear deck; a front truck and a rear truck which are respectively mounted underneath the front deck and the rear deck; front sliding units and rear sliding units which are respectively mounted to the front truck and the rear truck, the front sliding units and the rear sliding units being respectively arranged left and right of the front truck and the rear truck; a crossbar, of which both ends are coupled to the front truck and the rear truck, the crossbar being bent by external force for shaking the rear deck leftward and rightward to acquire propulsive power and being restored to an original shape when the external force is removed; a slider which is mounted to the crossbar below the front deck, the slider performing sliding motion on a lower surface of the front deck as the crossbar is bent; and a middle sliding unit which is horizontally turnably mounted to the slider and performs sliding motion together with the front sliding units and the rear sliding units.

[18] The front deck and the rear deck are formed with protruding portions at outward portions of steps, on which a rider s feet are put, to prevent the rider s feet from slipping outwardly from the front deck and the rear deck.

[19] The front sliding units, the rear sliding units, and the middle sliding unit are configured as wheels or blades.

[20] When the front sliding units, the rear sliding units, and the middle sliding unit are configured as wheels, shock-absorbing devices are mounted between the front truck and the front wheels and between the rear truck and the rear wheels to absorb shock from a road surface.

Advantageous Effects [21] According to the skateboard of the present invention, since the crossbar connecting the front deck and the rear deck gets bent by external force and restored to its original shape when the external force is removed, once the rear deck is shaken to any one direction (left or right) for acquiring propulsive power, a rider can easily shake the rear deck to the reverse direction with small force due to the elastic restoring force to restore the crossbar to its original shape, thereby easily acquiring the propulsive power.

[22] Because both ends of the crossbar are respectively coupled to the front truck and the rear truck, the long crossbar is bent to a large extent, and as a result strong propulsive power can be acquired.

[23] Also, because the slider provided with the middle wheel is mounted to the crossbar and the front deck extends longer than the rear deck to an extent of being positioned over the middle wheel, the crossbar is prevented from being bent downward and causing collapse of the front deck or the rear deck. Further, when the crossbar is bent leftward and rightward, the middle wheel is turned to the left and right corresponding thereto. Accordingly, the rider can stably skate and change the skating direction.

[24] Also, because the front deck and the rear deck are formed with the protruding portions, the rider s feet are prevented from slipping on the decks and falling down from the decks. By mounting the blades instead of the wheels (the front wheels, the rear wheels, and the middle wheel), the rider can enjoy the skateboard on the ice.

[25] Also, because the liner is mounted between the slider and the front deck, the liner prevents the slider from directly contacting the front deck and causing damage of the front deck when the slider performs sliding motion.

[26] Also, because the shock-absorbing devices are mounted between the front truck and the front wheels and between the rear truck and the rear wheels to absorb shock from the road surface, the direct transfer of the shock to the front or rear deck or to the rider can be prevented. Brief Description of the Drawings

[27] The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

[28] Fig. 1 is a plan view illustrating a conventional skateboard;

[29] Figs. 2 and 3 are operational state views of the conventional skateboard;

[30] Fig. 4 is a right side view illustrating a skateboard in accordance with a first embodiment of the present invention;

[31] Fig. 5 is a bottom view illustrating the skateboard in accordance with the first embodiment of the present invention;

[32] Fig. 6 is a sectional view illustrating the constitution and coupling structure of a crossbar depicted in Figs. 4 and 5;

[33] Fig. 7 is a sectional view taken along line A-A in Fig. 5;

[34] Fig. 8 is a sectional view taken along line B-B in Fig. 7;

[35] Figs. 9 and 10 are operational state views of the skateboard in accordance with the first embodiment of the present invention; [36] Fig. 11 is a right side view illustrating a skateboard in accordance with a second embodiment of the present invention; [37] Fig. 12 is a bottom view illustrating the skateboard in accordance with the second embodiment of the present invention; [38] Fig. 13 is a front view illustrating a skateboard in accordance with a third embodiment of the present invention;

[39] Fig. 14 is an enlarged sectional view of the C portion in Fig. 13;

[40] Fig. 15 is a right side view illustrating a skateboard in accordance with a fourth embodiment of the present invention; [41] Fig. 16 is a bottom view illustrating the skateboard in accordance with the fourth embodiment of the present invention;

[42] Fig. 17 is a cross-sectional view illustrating the H portion in Fig. 15;

[43] Fig. 18 is a perspective view illustrating an example of a crossbar depicted in Figs.

15 and 16;

[44] Fig. 19 is a cross-sectional view illustrating the A portion in Fig. 18;

[45] Fig. 20 is a sectional view taken along line B-B in Fig. 19;

[46] Fig. 21 is a sectional view taken along line C-C in Fig. 19;

[47] Figs. 22 to 24 are perspective views illustrating examples of a plate spring depicted in Fig. 18; [48] Figs. 25 and 26 are sectional views illustrating examples of a coating element depicted in Fig. 19; [49] Fig. 27 is a perspective view illustrating another example of the crossbar depicted in

Figs. 15 and 16;

[50] Fig. 28 is a cross-sectional view illustrating the D portion in Fig. 27;

[51] Fig. 29 is a sectional view taken along line E-E in Fig. 28;

[52] Fig. 30 is a perspective view illustrating a further example of the crossbar depicted in Figs. 15 and 16;

[53] Fig. 31 is a cross-sectional view illustrating the F portion in Fig. 30;

[54] Fig. 32 is a sectional view taken along line G-G in Fig. 31 ;

[55] Fig. 33 is a perspective view illustrating yet another example of the crossbar depicted in Figs. 15 and 16; [56] Fig. 34 is a plan view illustrating slanted plate members and connecting plate members depicted in Fig. 33; [57] Fig. 35 is a sectional view taken along line Z-Z in Fig. 15;

[58] Fig. 36 is a sectional view taken along line X-X in Fig. 16;

[59] Figs. 37 and 38 are sectional views taken along line Y-Y in Fig. 36;

[60] Fig. 39 is a sectional view illustrating an example of a brake depicted in Figs. 15 and 16;

[61] Fig. 40 is a perspective view illustrating an operating rod depicted in Fig. 39;

[62] Fig. 41 is a sectional view illustrating another example of the brake depicted in

Figs. 15 and 16; [63] Fig. 42 is a sectional view illustrating yet another example of the brake depicted in

Figs. 15 and 16; [64] Fig. 43 is a plan view illustrating a skateboard in accordance with a fifth embodiment of the present invention; [65] Fig. 44 is a right side view illustrating a skateboard in accordance with a sixth embodiment of the present invention; [66] Fig. 45 is a plan view illustrating the skateboard in accordance with the sixth embodiment of the present invention; [67] Fig. 46 is a front view illustrating a skateboard in accordance with a seventh embodiment of the present invention; [68] Fig. 47 is a bottom view illustrating the skateboard in accordance with the seventh embodiment of the present invention; [69] Fig. 48 is a plan view illustrating the skateboard in accordance with the seventh embodiment of the present invention; [70] Fig. 49 is a perspective view illustrating the skateboard in accordance with the seventh embodiment of the present invention; [71] Fig. 50 is a left side view illustrating the skateboard in accordance with the seventh embodiment of the present invention; [72] Fig. 51 is a right side view illustrating the skateboard in accordance with the seventh embodiment of the present invention; and [73] Fig. 52 is a bottom view illustrating left and right steering operations using a tie rod in a skateboard in accordance with an eighth embodiment of the present invention.

Best Mode for Carrying Out the Invention [74] Now, preferred embodiments of the present invention will be described in detail with reference to the annexed drawings. [75] Figs. 4 and 5 are a right side view and a bottom view illustrating a skateboard in accordance with a first embodiment of the present invention, respectively. [76] As shown in Figs. 4 and 5, the skateboard according to the first embodiment of the present invention comprises decks, trucks, wheels, a crossbar 400, a slider 500, and a liner 600.

[77] The decks include a front deck 110 and a rear deck 120, which a rider puts feet respectively on. The front deck 110 has a length Ll longer than the rear deck 120 (a length of the rear deck 120 is referred to by L2). The rear deck 120 is disposed in rear of the front deck 110 with a small gap G therebetween. However, the whole length (Ll + L2 + G) of the skateboard of this embodiment is not longer than that of the conventional skateboard shown in Fig. 1. When compared to the conventional skateboard, the front deck of the skateboard of this embodiment only extends rearward by a predetermined length.

[78] Grip tapes (not shown), which are configured as a sandpaper, may be attached to the upper surfaces of the front deck 110 and the rear deck 120. The outward portions of steps 112 and 122 of the front and rear decks 110 and 120 (which correspond to the front portion of the front deck and the rear portion of the rear deck), on which the rider s feet are put, are respectively formed with protruding portions 114 and 124 which protrude upward by a predetermined height.

[79] The protruding portions 114 and 124 prevent the rider s feet put on the steps 112 and 122 from unintentionally slipping outwardly from the steps 112 and 122.

[80] The trucks include a front truck 210 which is mounted underneath the front deck

110 and a rear truck 220 which is mounted underneath the rear deck 120. The front truck 210 consists of an upper body 212 and a lower body 214, and the rear truck 220 consists of an upper body 222 and a lower body 224.

[81] The upper bodies 212 and 222 of the front and rear trucks 210 and 220 are respectively disposed beneath the steps 112 and 122, and are securely mounted to the lower surfaces of the front deck 110 and the rear deck 120 by tightening mounting bolts 12.

[82] Wheels are rollably mounted to the rear left and right portions of the lower bodies

214 and 224 of the front and rear trucks 210 and 220. The front portions of the lower bodies 214 and 224 are respectively mounted underneath the upper bodies 212 and 222. The lower body 224 of the rear truck 220 can rotate horizontally with respect to the upper body 222. The lower body 214 of the front truck 210 may be horizontally rotatably mounted to the upper body 212, similarly to the lower body 224 of the rear truck 220, or may not.

[83] The upper bodies 212 and 222 of the front truck 210 and the rear truck 220 are respectively formed with insertion recesses 213 and 223 which are depressed to a predetermined depth on the inner surfaces of the upper bodies 212 and 222 opposing each other (refer to Fig. 6). The insertion recesses 213 and 223 are used for mounting the crossbar 400. The detailed description of the insertion recesses will be made later with the crossbar 400. [84] The wheels are sliding units enabling it to skate on the ground. The wheels include a pair of front wheels 310, a pair of rear wheels 320, and a middle wheel 330 which is provided between the front wheels 310 and the rear wheels 320.

[85] The front wheels 310 are rollably mounted to the rear left and right portions of the lower body 214 of the front truck 210, and the rear wheels 320 are rollably mounted to the rear left and right portions of the lower body 224 of the rear truck 220.

[86] The rear wheels 320 mounted to the lower body 224 of the rear truck 220 can be turned to the left and right. On the other hand, the front wheels 310 mounted to the lower body 214 of the front truck 210 may be turned to the left and right, or may not.

[87] Each of the front wheels 310 and the rear wheels 320 is disposed such that a line from the center of the wheel to the turning point of the wheel is slanted toward the progressing direction of the skateboard at a predetermined angle. Accordingly, when both the front wheels 310 and the rear wheels 320 are turnably mounted to the lower bodies 214 and 224 of the front and rear trucks 210 and 220, the front wheels 310 and the rear wheels 320 are always aligned straightly along the progressing direction of the skateboard.

[88] The middle wheel 330 will be described later together with the slider 500.

[89] Fig. 6 is a sectional view illustrating the constitution and coupling structure of the crossbar 400.

[90] Both ends of the crossbar 400 are respectively coupled to the front truck 210 and the rear truck 220, in order to connect the front deck 110 and the rear deck 120. The crossbar 400 is bent gently by force generated when shaking the rear deck 120 leftward and rightward, and is restored to its original shape when the force is removed.

[91] As shown in Fig. 6, the crossbar 400 includes a hollow cylindrical-shaped coil spring 410, a coating element 420 which envelops the coil spring 410, a reinforcement rod 430 which is inserted into the coil spring 410, and two caps 440 which are respectively coupled to both ends of the coil spring 410.

[92] Here, the coil spring 410 refers to an extension coil spring which is made by winding a wire in a helical shape such that adjacent coils contact each other. The coating element 420 functions to prevent foreign materials from infiltrating into the coil spring 410, and is made of a flexible material capable of permitting the deformation (bending) of the coil spring 410.

[93] The reinforcement rod 430 is for reinforcing the elastic force of the coil spring 410, and is made of an elastic material, such as rubber, urethane, or the like. The caps 440 coupled to both ends of the coil spring 410 are respectively fitted in the coupling recesses 213 and 223 of the front truck 210 and the rear truck 220, and are fixed to the front truck 210 and the rear truck 220 by tightening bolts 14.

[94] The crossbar 400 may consist of the coil spring 410 without the coating element 420 and the reinforcement rod 430, or may consist of the coil spring 410 and the coating element 420 without the reinforcement rod 430. Like this, when the reinforcement rod 430 is excluded from the constitution of the crossbar 400, the coil spring having a thicker thickness should be used to increase the elastic force correspondingly to the elastic force of the reinforcement rod 430.

[95] Fig. 7 is a sectional view taken along line A-A in Fig. 5, and Fig. 8 is a sectional view taken along line B-B in Fig. 7. Figs. 7 and 8 show the constitution of the slider 500 and the liner 600.

[96] As shown in Figs. 7 and 8, the slider 500 is mounted to surround the crossbar 400 below the front deck 110, and performs sliding motion on the lower surface of the front deck 110 as the crossbar 400 gets bent. The slider 500 includes a slider body 510 which the middle wheel 330 is rollably mounted below, a friction reducing means 520 which is mounted to the upper surface of the slider body 510 to reduce the friction when the slider body 510 performs the sliding motion, and a sleeve 530 which is interposed between the slider body 510 and the crossbar 400 to prevent the damage of the crossbar 400.

[97] The slider body 510 is tightly coupled to the crossbar 400 so as not to move along the crossbar 400. Although it is not illustrated in the drawings, the slider body 510 is configured such that it has separate left and right blocks and the left and right blocks are attached to each other by using bolts or the like.

[98] The friction reducing means 520 performs rolling motion underneath the front deck

110 to reduce the friction when the slider body 510 performs the sliding motion. As shown in Fig. 8 (A), the friction reducing means 520 is configured as balls 522, a portion of each being received in each of receiving recesses 512 formed at the upper surface of the slider body 510. Alternatively, as shown in Fig. 8 (B), the friction reducing means 520 is configured as a roller 524, a portion of which is received in a receiving recess 514 formed at the upper surface of the slider body 510.

[99] The slider body 510 is provided with guide rollers 526 at its front and rear ends.

The guide rollers 526 will be described later together with the liner 600.

[100] The slider 500 and the middle wheel 330 mounted to the slider 500 prevent the crossbar 400 from being bent downward and causing collapse of the front deck 110 or the rear deck 120. Similarly to the rear wheels 320, the middle wheel 330 can be turned to the left and right with respect to the slider body 510. Also, similarly to the front and rear wheels 310 and 320, the middle wheel 330 is disposed such that a line from the center of the wheel to the turning point of the wheel is slanted toward the progressing direction of the skateboard at a predetermined angle.

[101] The liner 600 prevents the slider 500 from directly contacting the front deck 110 and causing damage (wear or scratch) of the front deck 110. As shown in Figs. 7 and 8, the liner 600 is mounted to the lower surface of the front deck 110 to be disposed between the front deck 110 and the slider 500.

[102] The liner 600 is formed with side stoppers 602 at the left and right ends to restrict the left and right movement of the slider 500 within a predetermined limit. The liner 600 is further formed with a front stopper 610 and a rear stopper 620 respectively at the front end and the rear end to prohibit the front and rear movement of the slider 500. Accordingly, during the sliding motion, the slider 500 is prevented from being deviated to the left and right beyond the liner 600 by the side stoppers 602, and is prohibited to move to the front and rear by the front and rear stoppers 610 and 620.

[103] The front stopper 610 includes a vertical plate 612 which extends vertically from the front end of the liner 600, and a horizontal plate 614 which extends perpendicularly to the vertical plate 612 and rearward to define a guide space 616 with the liner 600.

[104] The rear stopper 620 includes a vertical plate 622 which extends vertically from the rear end of the liner 600, and a horizontal plate 624 which extends perpendicularly to the vertical plate 622 and forward to define a guide space 626 with the liner 600.

[105] The guide spaces 616 and 626 receive the guide rollers 526 of the slider 500. The guide roller 526 mounted to the front end of the slider 500 is positioned in the guide space 616 of the front stopper 610, and rolls on the horizontal plate 614. The guide roller 526 mounted to the rear end of the slider 500 is positioned in the guide space 626 of the rear stopper 620, and rolls on the horizontal plate 624.

[106] As shown in Figs. 9 and 10, when the rider puts feet on the front deck 110 and the rear deck 120 and shakes the rear deck 120 leftward and rightward around the coupling portion of the front truck 210 and the crossbar 400, the skateboard according to the first embodiment propels forward by the propulsive power due to reaction generated in the above shaking process. Once the rear deck 120 moves to any one direction (left or right), the crossbar 400 is elastically bent by the movement of the rear deck 120. Due to the elastic restoring force to restore the crossbar 400 to its original shape, the rider can easily move the rear deck 120 to the reverse direction with small force.

[107] When the crossbar 400 is bent to the left and right, the slider 500 moves to the left and right together with the crossbar 400, and the middle wheel 330 is turned to the left and right below the front deck 110. Accordingly, even when suddenly shifting the center of gravity to change the skating direction, the rider does not easily lose the balance. Such an operational effect is identically applied to the process for generating the propulsive power. Mode for the Invention

[108] Figs. 11 and 12 are a right side view and a bottom view illustrating a skateboard in accordance with a second embodiment of the present invention, respectively. [109] The skateboard according to the second embodiment has the same overall constitution and operation as the first embodiment, except that the sliding unit is configured as a blade in substitute for the wheel.

[110] In other words, as shown in Figs. 11 and 12, front blades 340 (instead of the front wheels 310 in the first embodiment) are mounted to the front truck 210, rear blades 350 (instead of the rear wheels 320 in the first embodiment) are mounted to the rear truck 220, and a middle blade 360 (instead of the middle wheel 330 in the first embodiment) is mounted to the slider 500.

[I l l] Different from the first embodiment, the above-structured skateboard according to the second embodiment is structured so that the rider can skate on the ice.

[112] Fig. 13 is a front view illustrating a skateboard in accordance with a third embodiment of the present invention.

[113] The skateboard according to the third embodiment has the same overall constitution and operation as the first embodiment, except that shock-absorbing devices 700 are mounted between the front truck 210 and the front wheels 310 and between the rear truck 220 and the rear wheels 320 to absorb the shock from the road surface and prevent the shock from being transferred to the front and rear decks 110 and 120 and the rider when skating.

[114] The shock- absorbing device 700 mounted between the front truck 210 and the front wheels 310, includes a pair of front arms 712, one end of each being vertically pivotably coupled to the lower surface of the lower body 214 of the front truck 210 and the other end of each being provided with each of the front wheels 310, and dampers 714 which are mounted between the front arms 712 and the lower body 214 of the front truck 210 to absorb the shock. The shock-absorbing device 700 mounted between the rear truck 220 and the rear wheels 320, includes a pair of rear arms 722, one end of each being vertically pivotably coupled to the lower surface of the lower body 224 of the rear truck 220 and the other end of each being provided with each of the rear wheels 320, and dampers 724 which are mounted between the rear arms 722 and the lower body 224 of the rear truck 220 to absorb the shock.

[115] The respective dampers 714 and 724 include up/down rods 732 which extend upward from the front and rear arms 712 and 722 to penetrate the lower bodies 214 and 224 of the front and rear trucks 210 and 220 and are formed with expanded portions 732a at upper ends to prevent separation from the lower bodies 214 and 224, and compression coil springs 734 which are disposed to surround the up/down rods 732 between the front and rear arms 712 and 722 and the lower bodies 214 and 224 of the front and rear trucks 210 and 220. The dampers 714 and 724 are not restricted to the above constitution, and can have other types of constitutions capable of absorbing the shock. [116] Fig. 14 is an enlarged sectional view of the C portion in Fig. 13, which shows the constitution for preventing the front wheels 310 and the rear wheels 320 from being slanted at a certain angle when the front arms 712 and the rear arms 722 are pivoted upward and compress the coil springs 734 of the dampers 714 and 724.

[117] Referring to Fig. 14, the ends of the front arms 712 and the rear arms 722 are vertically rotatably coupled to hubs 312 and 322 of the front wheels 310 and the rear wheels 320. The ends of the front arms 712 and the rear arms 722 are formed with cylindrical-shaped joints 314 and 324, and the hubs 312 and 322 are formed with joint sockets 312a and 322a in which the joints 314 and 324 are received.

[118] The front wheels 310 and the rear wheels 320 are provided with wheel supporting means 750 that support the front wheels 310 and the rear wheels 320 to be maintained in a vertical state.

[119] The wheel supporting means 750 include blocking portions 752 which are provided at the hubs 312 and 322 and in contact with the upper surfaces of the front arms 712 and the rear arms 722 when the front wheels 310 and the rear wheels 320 are in a vertical state to prevent the front arms 712 and the rear arms 722 from being pivoted downward, and elastic means 754 which are provided at the hubs 312 and 322 below the front arms 712 and the rear arms 722 to elastically support the front arms 712 and the rear arms 722.

[120] In Fig. 14, non-described reference numerals 316 and 326 refer to bearings, and reference numerals 318 and 328 refer to tires.

[121] Figs. 15 and 16 are a right side view and a bottom view illustrating a skateboard in accordance with a fourth embodiment of the present invention, respectively.

[122] As shown in Figs. 15 and 16, the skateboard according to the fourth embodiment of the present invention comprises decks, trucks, wheels, a crossbar 400, a slider 500, a liner 600, and a brake 800.

[123] The decks include a front deck 110 and a rear deck 120, which the rider puts feet respectively on. The front deck 110 has a length Ll longer than the rear deck 120 (a length of the rear deck 120 is referred to by L2). The rear deck 120 is disposed in rear of the front deck 110 with a small gap G therebetween. However, the whole length (Ll + L2 + G) of the skateboard of this embodiment is not longer than that of the conventional skateboard shown in Fig. 1. When compared to the conventional skateboard, the front deck of the skateboard of this embodiment only extends rearward by a predetermined length.

[124] Grip tapes, which are configured as a sandpaper, may be attached to the upper surfaces of the front deck 110 and the rear deck 120. The outward portions of steps 112 and 122 of the front and rear decks 110 and 120 (which correspond to the front portion of the front deck and the rear portion of the rear deck), on which the rider s feet are put, are respectively formed with protruding portions 114 and 124 which protrude upward by a predetermined height. The rear deck 120 is further formed with a mounting hole 126 in rear of the step 122, and the brake 800 is mounted through the mounting hole 126, which the rider steps on.

[125] The protruding portions 114 and 124 prevent the rider s feet put on the steps 112 and 122 from unintentionally slipping outwardly from the steps 112 and 122. However, the skateboard according to the present invention does not necessarily have the protruding portions 114 and 124.

[126] The trucks include a front truck 210 which is mounted underneath the front deck

[127] The upper bodies 212 and 222 of the front truck 210 and the rear truck 220 are respectively disposed beneath the steps 112 and 122 of the front deck 110 and the rear deck 120, and are securely mounted to the lower surfaces of the front deck 110 and the rear deck 120 by tightening mounting bolts. Wheels are rollably mounted to the rear left and right portions of the lower bodies 214 and 224 of the front truck 210 and the rear truck 220. The front portions of the lower bodies 214 and 224 are respectively mounted underneath the upper bodies 212 and 222.

[128] Fig. 35 is a sectional view taken along line Z-Z in Fig. 15, which shows the constitution of the rear truck 220.

[129] The rear truck 220 is configured such that the lower body 224 can rotate horizontally with respect to the upper body 222. As shown in Fig. 35, a restoring device is mounted between the upper body 222 and the lower body 224, to restore the lower body 224, which is rotated when shaking the rear deck 120 to the left and right, to its original position.

[130] The restoring device includes a guide recess 225 which is formed at the upper body

222 of the rear truck 220 by a predetermined angle along the rotational direction of the lower body 224, an insertion rod 226 which is inserted into the guide recess 225 and rotates together with the lower body 224, and coil springs 227 and 228 which are received in the guide recess 225 on both sides of the insertion rod 226 and are compressed according to the rotational direction of the insertion rod 226. The insertion rod 226 is formed at a hinge shaft of the lower body 224 of the rear truck 220 which is coupled to the upper body 222. The restoring device is not restricted to the above constitution, and can have other types of constitutions capable of restoring the rotating lower body 224 to its original position.

[131] The lower body 214 of the front truck 210 may be horizontally rotatably mounted to the upper body 212, similarly to the lower body 224 of the rear truck 220, or may not. [132] Fig. 17 is a cross-sectional view illustrating the H portion in Fig. 15. As shown in

Fig. 17, the upper bodies 212 and 222 of the front truck 210 and the rear truck 220 are respectively formed with insertion recesses which are depressed to a predetermined depth on the inner surfaces of the upper bodies 212 and 222 opposing each other. The insertion recesses are used for mounting the crossbar 400. The detailed description of the insertion recesses will be made later with the crossbar 400.

[133] The wheels are sliding units enabling it to skate on the ground. The wheels include a pair of front wheels 310, a pair of rear wheels 320, and a middle wheel 330 which is provided between the front wheels 310 and the rear wheels 320.

[134] The front wheels 310 are rollably and detachably mounted to the rear left and right portions of the lower body 214 of the front truck 210, and the rear wheels 320 are rollably and detachably mounted to the rear left and right portions of the lower body 224 of the rear truck 220.

[135] The rear wheels 320 mounted to the lower body 224 of the rear truck 220 can be turned to the left and right. On the other hand, the front wheels 310 mounted to the lower body 214 of the front truck 210 may be turned to the left and right, or may not.

[136] Each of the front wheels 310 and the rear wheels 320 is disposed such that a line from the center of the wheel to the turning point of the wheel is slanted toward the progressing direction of the skateboard at a predetermined angle. Accordingly, when both the front wheels 310 and the rear wheels 320 are turnably mounted to the lower bodies 214 and 224 of the front and rear trucks 210 and 220, the front wheels 310 and the rear wheels 320 are always aligned straightly along the progressing direction of the skateboard.

[137] The middle wheel 330 will be described later together with the slider 500. The front wheels 310, the rear wheels 320 and the middle wheel 330 can be substituted by blades which enable it to skate on the ice.

[138] An example of the crossbar 400 is depicted in Figs. 18 to 21.

[139] Both ends of the crossbar 400 are respectively coupled to the front truck 210 and the rear truck 220, in order to connect the front deck 110 and the rear deck 120. The crossbar 400 is bent gently by force generated when shaking the rear deck 120 leftward and rightward, and is restored to its original shape when the force is removed.

[140] As shown in Figs. 18 to 21, the crossbar 400 includes a plate spring 410 which is formed longitudinally and made of a metal material, a coating element 420 which envelops the plate spring 410, and two caps 430 which are respectively coupled to both ends of the coating element 420.

[141] Fig. 22 is a perspective view illustrating the above example of the plate spring 410.

[142] The plate spring 410 is made of steel which is mixed adequately to be used as a spring, i.e., made of spring steel. As shown in Fig. 22, the plate spring 410 is formed in a rectangular shape having a long length and a constant thickness. The plate spring 410 is erected while its both ends are respectively directed toward the front truck 210 and the rear truck 220. The plate spring 410 is formed with a plurality of coupling holes 412 which are disposed with a regular distance from each other along the longitudinal direction of the plate spring 410.

[143] It is described that the plate spring 410 is formed with a plurality of coupling holes

412 with reference to Fig. 22, however this is not restricted thereto. The plate spring 410 can be modified to have one coupling hole or more.

[144] Fig. 23 is a perspective view illustrating another example of the plate spring 410.

As shown in the drawing, the plate spring 410 includes a plurality of unit plate springs (not one plate spring), which are arranged with a regular gap and in parallel with each other so that flat surfaces 41Of of the unit plate springs oppose each other.

[145] A non-described reference numeral 411 in Fig. 23 refers to a separation member which functions to keep the gap between the adjacent unit plate springs constant.

[146] Fig. 24 is a perspective view illustrating yet another example of the plate spring

410. As shown in the drawing, similarly to the plate spring 410 depicted in Fig. 23, the plate spring 410 includes a plurality of unit plate springs, which are overlapped on each other so that flat surfaces 41Of of the unit plate springs oppose each other. Also, the unit plate springs have different lengths.

[147] A non-described reference numeral 413 in Fig. 24 refers to a binding member which functions to tightly bind the unit plate springs and prevent the separation thereof.

[148] The coating element 420 is formed in a lengthwise bar shape, and has a circular- shaped longitudinal- section and a constant thickness. Both ends of the coating element 420 are inserted into the insertion recesses of the front truck 210 and the rear truck 220, together with the caps 430. The coating element 420 is made of an elastic material having high elasticity, such as rubber, urethane, or the like.

[149] The coating element 420 enveloping the plate spring 410 minimizes twist of the plate spring 410, prevents the generation of defects (e.g., damage or breakage due to external force, or corrosion) of the plate spring 410, which may cause the deterioration of the elastic force, and supplements the elastic force of the plate spring 410 by its own elastic force.

[150] The coating element 420 is integrally formed with insertion portions 422 which are fitted through the coupling holes 412 of the plate spring 410. The insertion portions 422 and the coupling holes 412 increase the coupling force between the plate spring 410 and the coating element 420. Accordingly, the movement (especially, left and right movement and up and down movement in Fig. 6) of the plate spring 410 inside the coating element 420 is restricted, thereby preventing the coating element 420 from being torn or cracked due to the contact between the circumference of the plate spring 410 and the coating element 420.

[151] Figs. 25 and 26 are sectional views illustrating another example and yet another example of the coating element 420, respectively. As shown in the drawings, the coating element 420 can have an elliptical (not circular) or substantially rectangular- shaped longitudinal-section. In other words, the longitudinal- section of the coating element 420 is not restricted to any one particular shape, and can be formed in various shapes.

[152] Another example of the crossbar 400 is illustrated in Figs. 27 to 29.

[153] As shown in Figs. 27 to 29, this example of the crossbar 400 has the same overall constitution and operation as the previous example of the crossbar depicted in Figs. 18 to 21, except for the modified constitution of the plate spring 410. The plate spring 410 of the crossbar 400 depicted in Figs. 27 to 29 has structural features that a protruding portion 414 is formed at the bottom side in a width direction (an up/down direction in Fig. 28) of the plate spring 410.

[154] Describing in detail, the protruding portion 414 extends integrally from the plate spring 410 in the width direction, and is exposed outside of the coating element 420. Preferably, the exposed extent of the protruding portion 414 from the coating element 420 is constant.

[155] This example of the crossbar 400 structured as above has operational effects that when the rider performs a so-called rail slide (feat of sliding and moving on a rail structure), the crossbar 400 prevents the coating element 420 from directly contacting the rail structure and being worn.

[156] Yet another example of the crossbar 400 is illustrated in Figs. 30 to 32.

[157] As shown in Figs. 30 to 32, this example of the crossbar 400 has the same overall constitution and operation as the previous example of the crossbar depicted in Figs. 18 to 21, except that this example of the crossbar 400 further includes a linear liner 440 and binders 450.

[158] The linear liner 440 is positioned in alignment with the plate spring 410 in the width direction of the plate spring 410, and disposed on the outer circumference of the coating element 420 in the longitudinal direction of the coating element 420. The linear liner 440 is formed in a rod shape which has a thickness smaller than the coating element 420. The linear liner 440 has a constant circular-shaped longitudinal-section, and is made of a metal or synthetic resin material to have a predetermined strength.

[159] Each of the binders 450 is configured as a steel wire which functions to fix the linear liner 440 to the coating element 420 by binding the linear liner 440 to the coating element 420. A plurality of steel wires may be provided to be arranged with a regular distance from each other, or a single steel wire may be provided to be wound in a helical shape.

[160] The coating element 420 is provided with a receiving recess 424 which is formed in the longitudinal direction of the coating element 420 and has a constant depth and width. A portion of the linear liner 440 is received in the receiving recess 424 so that the movement of the linear liner 440 is prevented, and the remaining portion of the linear liner 440 is exposed outside of the receiving recess 424.

[161] The linear liner 440 has the same function as the protruding portion 414 depicted in

Figs. 27 to 29, however, has features capable of being separated from the coating element 420 over the protruding portion 414.

[162] Yet another example of the crossbar 400 is illustrated in Figs. 33 and 34.

[163] As shown in Figs. 33 and 34, this example of the crossbar 400 has the same overall constitution and operation as the previous example of the crossbar depicted in Figs. 18 to 21, except that the plate spring 410 of the previous example is substituted by a plurality of slanted plate members 470 and a plurality of connecting plate members 480. A reference numeral 490 in Fig. 33 refers to a coating element.

[164] The slanted plate members 470 are configured as a flat rectangular plate which is made of spring steel, and are arranged in one row with a regular gap from each other. More particularly, the slanted plate members 470 are arranged in a zigzag shape with a predetermined angle. Accordingly, when seen from above, a gap between first ends of the adjacent slanted plate members 470 is relatively narrow, and a gap between second ends of the adjacent slanted plate members 470 is relatively broad.

[165] The connecting plate members 480 are configured as a flat rectangular plate which is made of spring steel, similarly to the slanted plate members 470. The connecting plate members 480 are disposed between the adjacent slanted plate members 470 such that both ends of the connecting plate members 480 are integrally connected to the second ends of the adjacent slanted plate members 470 having the relatively broad gap therebetween. When seen from above, the connecting plate members 480 are arranged alternately on the left and right sides with respect to the row direction of the slanted plate members 470, and the connecting plate members 480 and the slanted plate members 470 make substantially triangular shapes. The triangular-shaped structure made by the connecting plate members 480 and the slanted plate members 470 is very mechanically effective, based upon the principle that a rectangular- shaped structure is easily deformed into a lozenge- shaped structure but a triangular- shaped structure is not easily deformed into other shapes.

[166] The connecting plate members 480 are formed in arc shapes which are curved inwardly, i.e., in an opposing direction to each other.

[167] The coating element 490 is coated on the slanted plate members 470 and the connecting plate members 480, and is formed in a bar shape having a constant thickness. The coating element 490 is made of an elastic material having high elasticity, such as rubber, urethane, or the like.

[168] Since the crossbar 400 depicted in Figs. 33 and 34 is configured such that the slanted plate members 470 are arranged in a zigzag shape and connected to each other by the connecting plate members 480, even if the coating element 490 is excluded from the constitution of the crossbar 400, an unintentional twist of the crossbar 400 can be prevented.

[169] Fig. 36 is a sectional view taken along line X-X in Fig. 16, and Figs. 37 and 38 are sectional views taken along line Y-Y in Fig. 36.

[170] As shown in Figs. 36 to 38, the slider 500 is mounted to surround the crossbar 400 below the front deck 110, and performs sliding motion on the lower surface of the front deck 110 as the crossbar 400 gets bent. The slider 500 includes a slider body 510 which the middle wheel 330 is rollably mounted below, a friction reducing means 520 which is mounted to the upper surface of the slider body 510 to reduce the friction when the slider body 510 performs the sliding motion, and a sleeve 530 which is interposed between the slider body 510 and the crossbar 400 to prevent the damage of the crossbar 400.

[171] The slider body 510 is tightly coupled to the crossbar 400 so as not to move along the crossbar 400. Although it is not illustrated in the drawings, the slider body 510 is configured such that it has separate left and right blocks and the left and right blocks are attached to each other by using bolts or the like.

[172] The friction reducing means 520 performs rolling motion underneath the front deck

110 to reduce the friction when the slider body 510 performs the sliding motion. As shown in Fig. 37, the friction reducing means 520 is configured as balls 522, a portion of each being received in each of receiving recesses 512 formed at the upper surface of the slider body 510. Alternatively, as shown in Fig. 38, the friction reducing means 520 is configured as a roller 524, a portion of which is received in a receiving recess 514 formed at the upper surface of the slider body 510.

[173] The slider body 510 is provided with guide rollers 526 at its front and rear ends.

The guide rollers 526 will be described later together with the liner 600.

[174] The slider 500 and the middle wheel 330 mounted to the slider 500 prevent the crossbar 400 from being bent downward and causing collapse of the front deck 110 or the rear deck 120. Similarly to the rear wheels 320, the middle wheel 330 can be turned to the left and right with respect to the slider body 510 and can be separated from the slider body 510. Also, similarly to the front and rear wheels 310 and 320, the middle wheel 330 is disposed such that a line from the center of the wheel to the turning point of the wheel is slanted toward the progressing direction of the skateboard at a predetermined angle. [175] The liner 600 prevents the slider 500 from directly contacting the front deck 110 and causing damage (wear or scratch) of the front deck 110. The liner 600 is mounted to the lower surface of the front deck 110 to be disposed between the front deck 110 and the slider 500.

[176] The liner 600 is formed with side stoppers 602 at the left and right ends to restrict the left and right movement of the slider 500 within a predetermined limit. The liner 600 is further formed with a front stopper 610 and a rear stopper 620 respectively at the front end and the rear end to prohibit the front and rear movement of the slider 500. Accordingly, during the sliding motion, the slider 500 is prevented from being deviated to the left and right beyond the liner 600 by the side stoppers 602, and is prohibited to move to the front and rear by the front and rear stoppers 610 and 620.

[177] The front stopper 610 includes a vertical plate 612 which extends vertically from the front end of the liner 600, and a horizontal plate 614 which extends perpendicularly to the vertical plate 612 and rearward to define a guide space 616 with the liner 600.

[178] The rear stopper 620 includes a vertical plate 622 which extends vertically from the rear end of the liner 600, and a horizontal plate 624 which extends perpendicularly to the vertical plate 622 and forward to define a guide space 626 with the liner 600.

[179] The guide spaces 616 and 626 receive the guide rollers 526 of the slider 500. The guide roller 526 mounted to the front end of the slider 500 is positioned in the guide space 616 of the front stopper 610, and rolls on the horizontal plate 614. The guide roller 526 mounted to the rear end of the slider 500 is positioned in the guide space 626 of the rear stopper 620, and rolls on the horizontal plate 624.

[180] Fig. 39 is a sectional view illustrating an example of the brake depicted in Figs. 15 and 16.

[181] As shown in Fig. 39, the brake 800 includes a housing 801 which is detachably mounted to the mounting hole 126 and formed with an opening in a vertical direction, an operating rod 802 which is vertically rotatably mounted to the opening of the housing 801 within a predetermined angle, and a coil spring 803.

[182] The operating rod 802 includes a manipulation portion which protrudes upward from the opening of the housing 801 by a predetermined height and the rider steps on, and a braking portion which extends downward from the manipulation portion and contacts the ground by being rotated when the rider steps on the manipulation portion. A rubber pad 804 is attached to the bottom of the braking portion.

[183] When the force of stepping on the manipulation portion of the operating rod 802 is removed, the operating rod 802 is returned to its original position by the elastic force of the coil spring 803.

[184] Fig. 40 is a perspective view of the operating rod 802. As shown in Fig. 40, the braking portion is formed in a fork shape. [185] Fig. 41 is a sectional view illustrating another example of the brake depicted in

Figs. 15 and 16. As shown in the drawing, this example of the brake is configured such that the coil spring 803 of the previous example is substituted by a plate spring 805 capable of returning the operating rod 802 to its original position when the force of stepping on the operating rod 802 is removed.

[186] Fig. 42 is a sectional view illustrating yet another example of the brake depicted in

Figs. 15 and 16. As shown in the drawing, this example of the brake is configured such that a saw blade 806 is attached to the bottom of the braking portion of the operating rod 802 in substitute for the rubber pad 804 of the previous example. The rubber pad 804 functions to increase the braking power when skating on the ground, and the saw blade 806 functions to increase the braking power when skating on the ice.

[187] Fig. 43 is a plan view illustrating a skateboard according to a fifth embodiment of the present invention.

[188] As shown in Fig. 43, the skateboard according to the fifth embodiment has the same overall constitution and operation as the fourth embodiment, except that the skateboard further includes manipulation handles 900 which the rider can shake the front deck 110 leftward and rightward by putting feet on while sitting on the rear deck 120.

[189] The manipulation handles 900 are detachably mounted to the left and right sides of the front deck 110. Each of the manipulation handles 900 includes a manipulation rod 910, and a mounting bracket 920 for mounting the manipulation rod 910 to the front deck 110.

[190] The manipulation rod 910 is horizontally pivotably coupled to the mounting bracket

920, and the mounting bracket 920 is fixed to the front deck 110 by tightening bolts.

[191] In other words, the manipulation rod 910 can be folded rearward along the side of the front deck 110 and spread from the front deck 110. The mounting bracket 920 is formed with a stopper that restricts the rotation of the manipulation rod 910 to prevent the manipulation rod 910 to be folded forward.

[192] While sitting on the rear deck 120, the rider puts feet on the manipulation handles

900 and pushes the manipulation handles 900 alternately to shake the front deck 110 leftward and rightward.

[193] Figs. 44 and 45 are a right side view and a plan view illustrating a skateboard in accordance with a sixth embodiment of the present invention, respectively.

[194] The skateboard according to the sixth embodiment has the same overall constitution and operation as the fourth embodiment or the fifth embodiment, except that the skateboard of this embodiment further includes snowboard plates enabling it to skate on the snow.

[195] The snowboard plates can be applied to the skateboard according to the fourth embodiment when the front wheels 310, the rear wheels 320, the middle wheel 330, and the brake 700 are demounted, and can be applied to the skateboard according to the fifth embodiment when the manipulation handles 900 are folded. The skateboard is detachably mounted onto the snowboard plates.

[196] As shown in Figs. 44 and 45, the snowboard plates include a front plate 810 and a rear plate 820. The front plate 810 and the rear plate 820 are formed with receiving recesses 812 and 822 on their upper surfaces, in which the front deck 110 and the rear deck 120 are respectively received.

[197] The present invention structured and operating as described above has the following advantages.

[198] Because the crossbar is constituted by the plate spring (or the slanted plate members and the connecting plate members) and the coating element enveloping the plate spring (or the slanted plate members and the connecting plate members), an unintentional twist of the plate spring (or the slanted plate members and the connecting plate members) can be prevented, and the plate spring (or the slanted plate members and the connecting plate members) can be protected from the exterior.

[199] Even without the middle wheel, the crossbar can be prevented from being bent downward due to the rider s weight. Also, since the crossbar has smooth and high elastic force, large propulsive power can be generated with small rider s force.

[200] Because the brake, which contacts the ground or the ice by being stepped on, is mounted to the rear deck, the rider can decelerate and stop the skateboard rapidly and accurately.

[201] If the rider puts feet on the manipulation handles mounted to the left and right sides of the front deck and pushes the manipulation handles alternately while sitting on the rear deck, the front deck is shaken leftward and rightward, and the skateboard slides. Accordingly, the rider can enjoy skating with being seated comfortably.

[202] Because the rear truck is provided with the restoring device that is capable of restoring the lower body of the rear truck, which is rotated when shaking the rear deck leftward and rightward to generate the propulsive power, to its original position, the rider can smoothly perform the operation for acquiring the propulsive power.

[203] Because the snowboard plates can be mounted to the skateboard while demounting the front wheels and the rear wheels, the rider can enjoy skating on the snow.

[204] The skateboard according to the present invention can be modified as illustrated in

Figs. 46 to 52.

[205] A tie rod for steering the sliding units is mounted between the left sliding unit and the right sliding unit of the front deck. Accordingly, if the left sliding unit is turned 50 degrees to the left, the right sliding unit is also turned 50 degrees to the left together with the left sliding unit. If the left sliding unit is turned 50 degrees to the right, the right sliding unit is also turned 50 degrees to the right together with the left sliding unit. In other words, the left sliding unit and the right sliding unit of the front deck are simultaneously turned to the left and right together with each other within a predetermined angle (e.g., 100 degrees) range. This is the same as a car steering mechanism that when a driver rotates a steering wheel left, left and right front wheels of a car are simultaneously turned to the left, and when a driver rotates a steering wheel right, left and right front wheels are simultaneously turned to the right. Such a steering mechanism is also applied to the left sliding unit and the right sliding unit of the rear deck. By using the above steering mechanism, oscillation phenomenon is eliminated, steering operation (turning to the left or right) can be smoothly achieved, and rectilinearity of the skateboard is improved.

[206] In order to provide stronger braking power during the skating, brake devices using plate springs are respectively mounted to the rear portions of the left sliding unit and the right sliding unit of the rear deck, and a tie rod is mounted onto the plate springs of the brake devices mounted to the left sliding unit and the right sliding unit. If the rider pushes down a push device provided on the rear deck, the tie rod moves downward, and the brake devices disposed beneath the tie rod transfer simultaneously braking power to the left and right sliding units (wheels). Since such a braking mechanism acts on both the wheels and the road surface, safer and more secure braking power can be ensured. If additionally mounting the brake devices to the wheels of the front deck, the braking power becomes much stronger.

[207] The skateboard of this embodiment further includes magnets which are attached to at least one of the sliding units of the front deck and the sliding units of the rear deck. Preferably, the magnets are arranged such that the same polarities of the magnets oppose each other between the sliding units of the front deck and between the sliding units of the rear deck. Accordingly, skating stability, steerability, rectilinearity, and oscillation prevention can be considerably improved.

[208] Hereinafter, the constitution of the skateboard of this embodiment will be described.

The tie rods 952 are mounted to connect the left sliding unit 310a and the right sliding unit 310a of the front deck 110 and connect the left sliding unit 320a and the right sliding unit 320a of the rear deck 120, in order to steer the sliding units. The tie rods 952 are made of metal or plastic, and are formed in a straight shape, a U shape, a convex lens shape, a concave lens shape, a spring shape, or the like. Both ends of the tie rods 952 may be formed with round recesses, or round protrusions. If the tie rods 952 are formed with round recesses at both ends, the tie rods 952 are coupled to the front or rear portions of the sliding units by using bolts and nuts, so that the sliding units can be turned together to the left and right within a predetermined angle (e.g., 100 degrees) range. If the tie rods 952 are formed with round protrusions at both ends, taps are formed at the tips of the round protrusions, to which nuts can be tightened. [209] The tie rods 952 can be adjusted in length according to the distance between the left sliding unit and the right sliding unit. For instance, each of the tie rods 952 includes a first pipe which is formed with nut type taps at both ends, and a second pipe which is formed with a bolt at one end. The bolt of the second pipe is tightened into the taps of the first pipe to adjust the whole length of the tie rod 952.

[210] Each of the brake devices for the sliding units includes the plate spring 951 mounted to the front or rear portion of each of the sliding units, and a friction member attached underneath the plate spring 951. The friction member is made of metal, plastic, rubber, or the like. The friction member is positioned at a gap from each of the front wheels 310 or the rear wheels 320. If the plate spring 951 is pushed downward, the friction member comes into contact with each of the wheels, thereby generating the braking power. If the force of pushing down the plate spring 951 is removed, the plate spring 951 and the friction member return to their original positions, and the braking power is released. The sliding units 310a and 320a, the tie rods 952, the plate springs 951, and the friction members can be fixed to each other by using bolts and nuts.

[211] Front or rear portions of the front deck 110 and the rear deck 120 are formed with mounting holes, and the push devices 950 are mounted through the mounting holes. The push devices 950 are elastically supported by the plate springs 951 or compression springs disposed below the decks, so that when the push devices 950 are pushed downward, the push devices 950 descend, and when the force of pushing down the push devices 950 is removed, the push devices 950 return to their original positions. The push devices 950 are positioned at a gap from the tie rods 952. The push devices 950 are fixed to the lower surfaces of the decks by tightening bolts.

[212] The present invention structured and operating as described above has the following advantages.

[213] Since the tie rods are mounted to connect the left sliding unit and the right sliding unit of the front deck and connect the left sliding unit and the right sliding unit of the rear deck, the left sliding units and the right sliding units can be turned to the same direction at the same angle. Accordingly, oscillation phenomenon is eliminated, and steering operation is performed smoothly.

[214] If stepping on the push device provided at the rear deck, the tie rod moves downward, and the friction members come into contact with the left and right wheels. At the same time, the braking power acts between the wheels and the road surface. Accordingly, the rider can decelerate and stop the skateboard rapidly and accurately.

[215] Also, because the magnets are attached to the sliding units of the front deck and the sliding units of the rear deck such that the same polarities of the magnets oppose each other between the sliding units of the front deck and between the sliding units of the rear deck, rectilinearity and steerability of the skateboard can be improved. Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

Claims

[1] A skateboard comprising: a rear deck; a front deck which is formed to have a length longer than the rear deck; a front truck and a rear truck which are respectively mounted underneath the front deck and the rear deck; front sliding units and rear sliding units which are respectively mounted to the front truck and the rear truck, the front sliding units and the rear sliding units being respectively arranged left and right of the front truck and the rear truck; a crossbar, of which both ends are coupled to the front truck and the rear truck, the crossbar being bent by external force for shaking the rear deck leftward and rightward to acquire propulsive power and being restored to an original shape when the external force is removed; a slider which is mounted to the crossbar below the front deck, the slider performing sliding motion on a lower surface of the front deck as the crossbar is bent; and a middle sliding unit which is horizontally turnably mounted to the slider and performs sliding motion together with the front sliding units and the rear sliding units.

[2] The skateboard according to claim 1, wherein the crossbar includes a coil spring, of which both ends are coupled to the front truck and the rear truck.

[3] The skateboard according to claim 1, wherein the crossbar includes a coil spring, of which both ends are coupled to the front truck and the rear truck, and a coating element which envelops the coil spring and is made of a flexible material.

[4] The skateboard according to claim 1, wherein the crossbar includes a coil spring, of which both ends are coupled to the front truck and the rear truck, a coating element which envelops the coil spring and is made of a flexible material, and a reinforcement rod which has elasticity and is inserted into the coil spring.

[5] The skateboard according to any one of claims 1 to 4, further comprising: a liner which is mounted to a lower surface of the front deck and positioned between the front deck and the slider.

[6] The skateboard according to claim 5, wherein the liner is formed with side stoppers at left and right ends to restrict left and right movement of the slider within a predetermined limit.

[7] The skateboard according to claim 6, wherein the liner is formed with a front stopper and a rear stopper respectively at a front end and a rear end to prohibit front and rear movement of the slider.

[8] The skateboard according to claim 7, wherein the slider includes a slider body which is mounted to surround the crossbar and the middle sliding unit is horizontally turnably mounted below, and at least one ball or roller which is mounted to an upper surface of the slider body to reduce friction between the slider body and the liner.

[9] The skateboard according to claim 8, wherein the slider further includes a sleeve which is interposed between the slider body and the crossbar.

[10] The skateboard according to claim 9, wherein the front stopper and the rear stopper include vertical plates which are respectively formed at front and rear ends of the liner, and horizontal plates which extend opposite to each other from lower ends of the respective vertical plates, the horizontal plates forming guide spaces with the liner, and the slider body is provided with guide rollers at front and rear ends which roll in the guide spaces.

[11] The skateboard according to claim 10, wherein the front deck and the rear deck are formed with protruding portions at outward portions of steps, on which a rider s feet are put, to prevent the rider s feet from slipping outwardly from the front deck and the rear deck.

[12] The skateboard according to claim 11, wherein the front sliding units, the rear sliding units, and the middle sliding unit are configured as front wheels, rear wheels, and a middle wheel, respectively.

[13] The skateboard according to claim 11, wherein the front sliding units, the rear sliding units, and the middle sliding unit are configured as blades for skating on ice.

[14] The skateboard according to claim 12, further comprising: shock-absorbing devices which are mounted between the front truck and the front wheels and between the rear truck and the rear wheels to absorb shock from a road surface.

[15] The skateboard according to claim 14, wherein the shock-absorbing device mounted between the front truck and the front wheels includes a pair of front arms, one end of each being vertically pivotably coupled to a lower surface of the front truck and the other end of each being provided with each of the front wheels, and dampers which are mounted between the front arms and the front truck to absorb shock, and the shock-absorbing device mounted between the rear truck and the rear wheels includes a pair of rear arms, one end of each being vertically pivotably coupled to a lower surface of the rear truck and the other end of each being provided with each of the rear wheels, and dampers which are mounted between the rear arms and the rear truck to absorb shock.

[16] The skateboard according to claim 15, wherein ends of the front arms and the rear arms are vertically rotatably coupled to hubs of the front wheels and the rear wheels, and the front wheels and the rear wheels are provided with wheel supporting means which support the front wheels and the rear wheels to be maintained in a vertical state.

[17] The skateboard according to claim 16, wherein the wheel supporting means include blocking portions which are provided at the hubs and in contact with upper surfaces of the front arms and the rear arms when the front wheels and the rear wheels are in a vertical state to prevent the front arms and the rear arms from being pivoted downward, and elastic means which are provided at the hubs below the front arms and the rear arms to elastically support the front arms and the rear arms.

[18] A skateboard comprising: a rear deck; a front deck which is formed to have a length longer than the rear deck; a front truck which is mounted underneath the front deck; a rear truck which is horizontally rotatably mounted underneath the rear deck; front wheels and rear wheels which are respectively detachably mounted to the front truck and the rear truck, the front wheels and the rear wheels being respectively arranged left and right of the front truck and the rear truck; a crossbar, of which both ends are coupled to the front truck and the rear truck, the crossbar being bent by external force for shaking the rear deck leftward and rightward to acquire propulsive power and being restored to an original shape when the external force is removed; and a slider which is mounted to the crossbar below the front deck, the slider performing sliding motion on a lower surface of the front deck as the crossbar is bent, wherein the crossbar includes at least one plate spring which is erected while both ends are respectively directed toward the front truck and the rear truck, and a coating element which envelops the plate spring, is formed in a bar shape having a constant thickness, has both ends coupled to the front truck and the rear truck, and is made of an elastic material, and when the crossbar includes plural plate springs, the plural plate springs are arranged with a regular gap and in parallel with each other or overlapped on each other so that flat surfaces of the plural plate springs oppose each other.

[19] The skateboard according to claim 18, wherein the plate spring is formed with at least one coupling hole, and the coating element is formed with at least one insertion portion which is fitted through the coupling hole of the plate spring.

[20] The skateboard according to claim 18 or 19, wherein the plate spring is formed with a protruding portion which extends from a bottom side in a width direction of the plate spring and is exposed outside of the coating element to a constant extent.

[21] The skateboard according to claim 18, wherein the crossbar includes a liner which is disposed on a lower outer circumference of the coating element in a longitudinal direction of the coating element and is formed in a rod shape having a thickness smaller than the coating element, and a binder which fixes the liner to the coating element.

[22] The skateboard according to claim 21, wherein the coating element is provided with a receiving recess which is formed at the lower outer circumference in the longitudinal direction of the coating element to receive a portion of the liner.

[23] The skateboard according to claim 18, further comprising: a middle wheel which is horizontally turnably and detachably mounted to the slider and performs rolling motion together with the front wheels and the rear wheels.

[24] The skateboard according to claim 18, further comprising: a brake which is detachably mounted to the rear deck, and comes into contact with a surface on which the skateboard slides to generate braking power when being stepped on.

[25] The skateboard according to claim 24, wherein the brake includes: a housing which is detachably mounted to a mounting hole formed at a rear portion of the rear deck and is formed with an opening in a vertical direction; an operating rod which has a manipulation portion which is vertically rotata bly mounted to the opening of the housing within a predetermined angle and protrudes upward from the opening by a predetermined height to be stepped on, and a braking portion which extends downward from the manipulation portion and contacts the surface on which the skateboard slides when the manipulation portion is rotated by being stepped on; and an elastic member which returns the operating rod to an original position when force of stepping on the operating rod is removed.

[26] The skateboard according to claim 25, wherein the braking portion is formed in fork shape.

[27] The skateboard according to claim 25 or 26, wherein the braking portion is provided with a rubber pad which is attached to a contact portion with the surface on which the skateboard slides.

[28] The eboard according to claim 25 or 26, wherein the braking portion is provided with a saw blade which is attached to a contact portion with the surface on which the skateboard slides.

[29] The skateboard according to claim 18, wherein the rear truck includes an upper body which is mounted to a lower surface of the rear deck, a lower body which is horizontally rotatably coupled to the upper body, and a restoring device which is mounted between the upper body and the lower body to restore the lower body, which is rotated when shaking the rear deck to the left and right, to an original position.

[30] The skateboard according to claim 18, wherein the front deck is provided with manipulation handles which are detachably mounted to left and right sides of the front deck so that a rider shakes the front deck leftward and rightward by putting feet on the manipulation handles while sitting on the rear deck.

[31] The skateboard according to claim 30, wherein the manipulation handles are configured to be folded along the left and right sides of the front deck and spread from the front deck.

[32] The skateboard according to claim 18, further comprises: snowboard plates, onto which the skateboard is mounted while the front wheels and the rear wheels are demounted, to enable it to skate on snow.

[33] The skateboard according to claim 32, wherein the snowboard plates include a front plate and a rear plate, and the front plate and the rear plate are formed with receiving recesses on upper surfaces, in which the front deck and the rear deck are respectively received.

[34] A skateboard comprising: a rear deck; a front deck which is formed to have a length longer than the rear deck; a front truck which is mounted underneath the front deck; a rear truck which is horizontally rotatably mounted underneath the rear deck; front wheels and rear wheels which are respectively detachably mounted to the front truck and the rear truck, the front wheels and the rear wheels being respectively arranged left and right of the front truck and the rear truck; a crossbar, of which both ends are coupled to the front truck and the rear truck, the crossbar being bent by external force for shaking the rear deck leftward and rightward to acquire propulsive power and being restored to an original shape when the external force is removed; and a slider which is mounted to the crossbar below the front deck, the slider performing sliding motion on a lower surface of the front deck as the crossbar is bent, wherein the crossbar includes a plurality of slanted plate members which are arranged in one row with a regular gap from each other between the front truck and the rear truck and arranged in a zigzag shape with a predetermined angle, and connecting plate members which are disposed between the adjacent slanted plate members such that both ends of the connecting plate members are connected to ends of the adjacent slanted plate members having a relatively broad gap therebetween, and are arranged alternately on left and right sides with respect to a row direction of the slanted plate members. [35] The skateboard according to claim 34, wherein the crossbar further includes a coating element which envelops the slanted plate members and the connecting plate members, the coating element being formed in a bar shape having a constant thickness and made of an elastic material. [36] The skateboard according to claim 34 or 35, wherein the connecting plate members are formed in arc shapes which are curved inwardly in an opposing direction to each other. [37] A skateboard comprising: a rear deck; a front deck which is formed to have a length longer than the rear deck; front sliding units and rear sliding units which are respectively mounted to the front deck and the rear deck; a front steering device which connects the front sliding units arranged left and right of the front deck; a rear steering device which connects the rear sliding units arranged left and right of the rear deck; brake devices which are mounted to the rear sliding units; a push device which is provided on the rear deck, the push device moving the rear steering device and the brake devices downward to generate braking power when the push device is pushed down; a crossbar which connects the front deck and the rear deck, the crossbar being bent by external force for shaking the rear deck leftward and rightward and being restored to an original shape when the external force is removed; and a slider which is mounted to the crossbar below the front deck, the slider performing sliding motion on a lower surface of the front deck. [38] The skateboard according to claim 37, wherein the front steering device and the rear steering device are configured as tie rods. [39] The skateboard according to claim 38, wherein each of the tie rods functions to turn the front or rear sliding units arranged left and right of the front deck or the rear deck to the same direction at the same angle, the tie rods are made of a metal or plastic material, the tie rods are formed in a shape selected from the group consisting of a straight shape, a U shape, a convex lens shape, a concave lens shape, and a spring shape, and each of the tie rods is formed with round recesses or round protrusions at both ends. [40] The skateboard according to claim 39, wherein each of the tie rods includes a first pipe which is formed with nut type taps at both ends, and a second pipe which is formed with a bolt at one end, the bolt of the second pipe being tightened into the taps of the first pipe, whereby the tie rods are adjusted in length. [41] The skateboard according to claim 37, further comprises: brake devices which are mounted to the front sliding units. [42] The skateboard according to claim 41, wherein the front steering device is disposed between the brake devices which are mounted to the front sliding units arranged left and right of the front deck, and the rear steering device is disposed between the brake devices which are mounted to the rear sliding units arranged left and right of the rear deck. [43] The skateboard according to claim 41, wherein the rear steering device is disposed between the brake devices which are mounted to the rear sliding units arranged left and right of the rear deck. [44] The skateboard according to claim 37, wherein only the rear deck or both the front deck and the rear deck are formed with holes, each of the holes having a shape selected from the group consisting of a rectangular shape, a circular shape, a semicircular shape, and a crescent shape, and the push device is inserted through each of the holes. [45] The skateboard according to claim 44, wherein when the push device is pushed down by external force, the push device moves downward and pushes down the steering device which connects the left and right sliding units where the brake device is mounted, to generate braking power, and when the external force of pushing down the push device is removed, the push device returns to an original position, and the braking power is released. [46] The skateboard according to claim 37, further comprising: magnets which are attached to at least one of the front sliding units or the rear sliding units. [47] The skateboard according to claim 46, wherein the magnets are attached to only the front sliding units.