CN203841421U

CN203841421U - Multi-purpose infant bed

Info

Publication number: CN203841421U
Application number: CN201420166679.7U
Authority: CN
Inventors: 张燕华; 马保海
Original assignee: Individual
Current assignee: Individual
Priority date: 2014-04-04
Filing date: 2014-04-04
Publication date: 2014-09-24
Anticipated expiration: 2024-04-04

Abstract

The utility model discloses a multi-purpose infant bed. The multi-purpose infant bed comprises a bed board, wherein a front hydraulic cylinder is respectively fixedly arranged on the two sides of the front end of the bed board; a back hydraulic cylinder is respectively fixedly arranged on the two sides of the back part of the bed board; a battery and an electric motor which are electrically connected, and a hydraulic device driven by the electric motor are arranged on the bottom of the bed board; the output end of the hydraulic device is respectively connected with the front hydraulic cylinders and the back hydraulic cylinders through a control valve and drives the front and back hydraulic cylinders to do telescopic motion; the multi-purpose infant bed further comprises a controller for controlling the electric motor to work and driving the control valve to work; the base is provided with a front switching button for controlling motion of a front switching valve, a front stopping button for controlling motion of a front stop valve, a back switching button for controlling motion of a back switching valve, and a back stopping button for controlling motion of the back stop valve; a pedal is hinged to the base; the two ends of the pedal are respectively in pressing fit with both the front switching button and the back switching button. The multi-purpose infant bed can swing an infant lightly, is time-saving and force-saving to operate, can guide the infant to think about a moving or swinging object, is good for prompting intelligence development of the infant, and lightens burden of mothers.

Description

Multipurpose Baby bed

Technical field

The utility model relates to multipurpose Baby bed.

Background technology

Infant generally can not walk within 1 years old, now mainly relied on father and mother to have in arms to walk about, observed, cognitive extraneous things, and so just to father and mother, particularly mother's physical fitness requirement is higher.If mother not yet comes from fertility child's recovering state, or mother is more thin and weak, be difficult to the important task that complete independently is fostered infant.Now the infant intelligence level of birth is more and more higher, if wake up in sleep or find that mother has stealthily been placed on him on bed, can crying of a child wail, thereby require mother to have him in arms, fooling him, mother is just more tired, even more tired like this.

In order to solve the problem that holds a baby in one's arms or fool child, father and mother generally use cradle or shaking table now, this bed is exactly by articulated manner, a bed board or bed frame to be installed on bedstead, and the mode by reciprocally swinging bed board or bed frame plays the object of rocking child on bed board.This cradle structure is simple, cost is lower, use very wide, but its weak point is, the amplitude of fluctuation of this shaking table and frequency depend on swing dynamics and the speed of mother's arm completely, so mother still needs to consume larger muscle power, if the frequency or the changes in amplitude that swing are larger, easily wake baby up, therefore mother's operant level is had relatively high expectations, practical operation effect is unsatisfactory.Traditional shaking table or multipurpose Baby bed do not have for baby's amusement or attract its curiosity to guide the function of its thinking, can only come baby soothing or roars of laughter child by the mode of rocking bed body, and function singleness, is unfavorable for the growth of infant intelligence potentiality or excavation.

Utility model content

The technical problems to be solved in the utility model is to provide a kind of rational in infrastructure for above-mentioned deficiency, can softly rock baby, rock dynamics, velocity-stabilization, it is time saving and energy saving to operate, the thinking that can guide baby that article are moved or swung, and contribute to guiding or promote the multipurpose Baby bed that infant intelligence is grown.

For solving the problems of the technologies described above, this multipurpose Baby bed comprises bed board, bed board end face surrounding is installed with fence, its design feature is: bed board front part sides is installed with respectively front hydraulic cylinder, the front hydraulic stem lower end of front hydraulic cylinder is provided with front-wheel, both sides, bed board rear portion are installed with respectively rear hydraulic cylinder, the rear hydraulic stem lower end of rear hydraulic cylinder is provided with trailing wheel, bed board bottom is provided with battery and the motor being electrically connected, and by electric motor driven hydraulic means, the output of hydraulic means is connected with rear hydraulic cylinder with front hydraulic cylinder by control valve respectively and drives its expanding-contracting action, also comprise the controller of controlling motor work and drive control valve action, described control valve comprises controls the front transfer valve that front hydraulic cylinder extension action is switched, control the hydraulic means front stop valve of hydraulic cylinder oil supply loop break-make forward, the rear transfer valve that after controlling, hydraulic cylinder extension action is switched, control the hydraulic means rear stop valve of hydraulic cylinder oil supply loop break-make backward, described controller comprises base, the front switching push button of transfer valve action before base is provided with and controls, the front cut-off button of stop valve action before controlling, the rear switching push button of transfer valve action after controlling, the rear cut-off button of stop valve action after controlling, also comprise the start button being serially connected in electric electromechanics resource loop, on base, be hinged with pedal, interference fit is pressed with front switching push button and rear switching push button respectively in pedal two ends, on the fence of tailstock portion, be installed with sleeve, in sleeve, be fitted with upwardly extending support bar, post upper is installed with the trunnion axis laterally be arrangeding in parallel with bed board, trunnion axis middle part is set with the pivoted housing that can rotate around trunnion axis, on pivoted housing, be installed with the fork to downward-extension, on pivoted housing, be coaxially installed with drive bevel gear, trunnion axis end is fixed with head-shaped riser by the connecting rod extending to head of a bed portion, riser top is provided with the through hole that two horizontal intervals arrange, in through hole, by vertical axis, be hinged with and turn ball, rotating shaft is installed with swing arm near a side of trunnion axis, also comprise the two ends tooth bar hinged with two swing arm ends respectively, connecting rod middle part is provided with rotating shaft, rotating shaft one end is installed with the driven wheel of differential with drive bevel gear engagement, the rotating shaft other end is installed with and tooth bar meshed gears.

Bed board is carrying baby's agent structure, and bed board bottom is provided with two groups of hydraulic support mechanisms, for convenience of narration, is called front support group and rear support group.Wherein, front support group comprises the front hydraulic cylinder that is arranged on the anterior left and right sides of bed board, and the front hydraulic stem of front hydraulic cylinder is flexible downwards, and front hydraulic stem lower end is provided with the front-wheel of the front hydraulic stem of rolling support.Rear support group comprises the rear hydraulic cylinder that is arranged on the left and right sides, bed board rear portion, and the rear hydraulic stem of rear hydraulic cylinder is flexible downwards, and rear hydraulic stem lower end is provided with the trailing wheel of hydraulic stem after rolling support.Under normal circumstances, the minimum number of front hydraulic cylinder and rear hydraulic cylinder is all two covers, between left and right every setting.Bed board bottom is also provided with the hydraulic means being connected with rear hydraulic cylinder with front hydraulic cylinder by control valve, and hydraulic means is by Motor Drive, and motor is by the powered battery being arranged on bed board.By drive control valve, move and can realize corresponding hydraulic cylinder and hydraulic stem contraction or overhanging relatively, also just played and driven the flexible of corresponding support group.By the extension and contraction control to the logicality of front support group and these two groups of support groups of rear support group, can realize bed board imitation mother baby and hold in the arms regular rocking, thereby play the effect that tenderness is rocked baby, baby soothing sleep.

In this multipurpose Baby bed, described control valve comprises front transfer valve, front stop valve, rear transfer valve and rear stop valve.Wherein, the Main Function of front transfer valve is that hydraulic oil circulation passage or the circulating direction of front hydraulic cylinder are switched, thereby realize, front hydraulic stem stretches out or the switching of contractive action.The Main Function of front stop valve is the break-make of hydraulic cylinder hydraulic oil circulation passage before controlling, thereby realizes the retentive control that front hydraulic stem is stretched out to front hydraulic cylinder state, is also just equivalent to the duty switch of front hydraulic cylinder.By the logic control to front stop valve and front transfer valve, also just can realize control and the maintenance of front hydraulic stem and any stroke of front hydraulic cylinder.Same, the effect of rear stop valve and rear transfer valve is identical therewith, at this, no longer carefully states.Start button mainly starts to control turn-on motor power, the effect that motor is started working.

In this multipurpose Baby bed, the driving work of the work of motor and control valve is completed by controller.Controller mainly comprises a base, and described front transfer valve, front stop valve, rear transfer valve and rear stop valve are all arranged on base.On base, going back hinged support has pedal, and pedal can swing at the supporting role lower stress of jointed shaft.Front switching push button and rear switching push button match with the two ends of pedal respectively, will trigger so front switching push button or rear switching push button when pedal swinging, thereby play by pedal, control two support group expanding-contracting actions, have also just played the effect of rocking bed board.Therefore, when practical operation, can gently step on pedal swinging with pin and realize the function that drives bed board to rock by electric power or hydraulic means, both baby need not be had in arms and also baby need not be rocked, simple to operate, time saving and energy saving, mother or more thin and weak mother of being particularly suitable for own baby-sit nurse baby's use.Because this multipurpose Baby bed is to realize the lifting of bed board by hydraulic way, therefore, rise or decline and all relatively relax, and noiselessness, contribute to baby sleep.

By the mode of foot pedals, have multiplely, in brief, can be divided into and singly step on and twoly step on two kinds.Singly step on exactly and to step on pedal sole is whole, swing with whole sole control pedal, but only with sole front portion tiptoe or be only that heel firmly presses down with sole rear portion namely, switching push button or the only rear switching push button action of triggering before namely only triggering, so just can realize bed board one end maintains static and only drives front support group expanding-contracting action or only drive rear support group expanding-contracting action, thereby reach the effect that rock one end, while being equivalent to the action of two groups of support group simultaneous retractables, rock half of effect, be applicable to using than more sensitive baby, can select according to actual needs.Corresponding, two stepping on is exactly tiptoe and the heel asynchronous behavior that matches, thereby realize the work that asynchronous expanding-contracting action is organized in two groups of supports, also just having reached the anterior rear portion simultaneously of rising of bed board declines, and on the anterior rear portion simultaneously of declining, rise significantly rock effect, be applicable to using rocking the baby that effect requirements is higher.Therefore, this multipurpose Baby bed can be applicable to dissimilar baby to be used, or applicable baby uses in different phase, and versatility is better.

In this multipurpose Baby bed, sleeve oral area is upwards fixedly mounted on fence, and support bar and sleeve up and down plug-in mounting coordinate, and support bar can not rotate relative to sleeve in sleeve, while rocking control bed board with controller before and after like this, support bar rocks before and after also must be thereupon.Post upper is installed with trunnion axis, trunnion axis be not only horizontally disposed with and also trunnion axis along bed board horizontally set.On trunnion axis, be set with pivoted housing, pivoted housing can rotate around trunnion axis, is installed with the fork to downward-extension on pivoted housing.When roars of laughter child amusement, bed board rocks before and after under controller is controlled, and now pivoted housing is because its outside is installed with fork and causes bias or lay particular stress on, so fork also can swing centered by trunnion axis thereupon.Drive bevel gear is installed on pivoted housing, and drive bevel gear and pivoted housing coaxially arrange.When pivoted housing rotates, drive bevel gear is also inevitable synchronously rotates thereupon.

Trunnion axis end is provided with a riser by link supports, and riser vertically arranges, and is arranged to head-shaped with apish " head ".Riser top is provided with two spaced through holes, and this through hole is equivalent to " eye socket " of " head ".The interior vertical axis by vertical setting of through hole is hinged with and turns ball, and turning ball can rotate around vertical axis, turns " eyeball " or " eyeball " that ball is equivalent to eyes.For convenience of narration, by turning ball one end towards head of a bed portion, be called front end or front side or outside or outer end, the other end is called to rear end rear side or inner side or the inner.Turn ball inner side and be installed with swing arm, settings that stretch out of swing arm Cong Zhuan ball center, generally extends setting towards trunnion axis.Between two swing arms, be connected with tooth bar, the flank of tooth of tooth bar arranges upward, and tooth bar two ends are corresponding hinged with two swing arm ends by the hinge vertically arranging respectively.Such two swing arms or two turn ball and just by rack-driving, link together, and can realize the interlock between three.Connecting rod middle part is rotatablely equipped with rotating shaft, and rotating shaft one end is provided with the driven wheel of differential with drive bevel gear engagement, and the rotating shaft other end is provided with and tooth bar meshed gears.Pivoted housing will move by drive bevel gear, driven wheel of differential, rotating shaft and gear driving rack successively like this, and namely driving turns ball rotates around vertical axis, has also just been equivalent to the action of " eyeball stravismus " or " pearl in an instant ".When pivoted housing rotates backward, " eyeball " oppositely looked side ways or reverse " pearl in an instant ".Like this, along with rock the front and back of bed board, pivoted housing comes and goes and rotates, " eyeball " also just swings, and not only can play the effect of amusing baby, can also attract baby's notice, guide its swing of thinking deeply object, rotation etc. naturally to imagine, help lend some impetus to its intelligence development.Because the action of " pearl in an instant " is rotational action and is driven by the engagement of each gear therefore almost there is no noise, when baby need to sleep, can be on baby's impact of being burdened with, certain, also can directly support bar be extracted in sleeve, operate very simple.

As improvement, turn ball and be pasted with color chips towards a side of head of a bed portion.

In the outer end that turns ball, stick after color chips, make " eyeball " more vivid, more true to nature, contribute to attract and amuse baby.

As improvement, on front hydraulic cylinder outer wall, be installed with the front limit bar extending to front-wheel, front hydraulic stem middle part is installed with the front triggering block that extend at gag lever post middle part forward, and front limit bar two ends are provided with the front limit switch corresponding with front triggering block, and front limit switch series is connected in the current supply circuit of motor.

Because front limit bar arranges along front hydraulic stem, that is to say that both are parallel or approximate be arrangeding in parallel.Current hydraulic stem relatively before hydraulic stem when flexible, front triggering block is synchronizing moving thereupon also.Under normal circumstances, in the scope that the flexible scope of front hydraulic stem can only make front triggering block answer at front limit pole pair, move, can make like this rocking in the scope that can accept baby of bed board.But when breaking down, the flexible meeting of front hydraulic stem makes front triggering block exceed this scope.When current triggering block touches the front limit switch at front limit bar two ends; triggering front limit switch is switched to normally open by normally off; now front limit switch can cut off the current supply circuit of motor, and this multipurpose Baby bed is shut down, and has played protection baby's effect.

As improvement, on rear hydraulic cylinder outer wall, be installed with the rear gag lever post extending to trailing wheel, rear hydraulic stem middle part is installed with the rear triggering block that extend at gag lever post middle part backward, and rear gag lever post two ends are provided with the rear limit switch corresponding with rear triggering block, and rear limit switch is serially connected in the current supply circuit of motor.

Rear triggering block is the same with the matching relationship of front triggering block and front limit switch with the matching relationship of rear limit switch, at this, no longer carefully states.

In sum, adopt the multipurpose Baby bed of this structure rational in infrastructure, can softly rock baby, rock dynamics, velocity-stabilization, it is time saving and energy saving to operate, and is not only applicable to roars of laughter baby sleep but also be applicable to guiding baby amusement, the thinking that can guide baby that article are moved or swung, help lend some impetus to infant intelligence and grow, effectively alleviated mother's burden.

Accompanying drawing explanation

By reference to the accompanying drawings the utility model is described in further detail:

Fig. 1 is the structural representation of the utility model nature;

Fig. 2 is electrical schematic diagram of the present utility model;

Fig. 3 is the fit structure schematic diagram of rack and pinion.

The specific embodiment

As shown in the figure, this multipurpose Baby bed comprises bed board 1, and bed board 1 is rectangular flat plate, and bed board end face surrounding is installed with fence 8.Bed board front part sides is installed with respectively front hydraulic cylinder 2, front hydraulic stem 3 lower ends of front hydraulic cylinder are provided with front-wheel 4, both sides, bed board rear portion are installed with respectively rear hydraulic cylinder 5, rear hydraulic stem 6 lower ends of rear hydraulic cylinder are provided with trailing wheel 7, bed board bottom is provided with battery 11 and the motor 12 being electrically connected, and by electric motor driven hydraulic means 13, the output of hydraulic means is connected with rear hydraulic cylinder with front hydraulic cylinder by control valve 14 respectively and drives its expanding-contracting action.Described control valve comprises the front transfer valve 15 controlling front hydraulic cylinder extension action and switch, control hydraulic means forward hydraulic cylinder oil supply loop break-make front stop valve 16, control after the rear transfer valve 19 that switches of hydraulic cylinder extension action, the control hydraulic means rear stop valve 20 of hydraulic cylinder oil supply loop break-make backward.Also comprise the controller 9 of controlling motor work and drive control valve action, controller comprises base 10, base is provided with the rear cut-off button 26 of the front switching push button 21 of the front transfer valve action of control, the front cut-off button 22 that the front stop valve of control moves, the rear switching push button 25 of controlling rear transfer valve action, the rear stop valve action of control, also comprise the start button 27 being serially connected in electric electromechanics resource loop, on base, be hinged with pedal 17, interference fit is pressed with front switching push button and rear switching push button respectively in pedal two ends.

In this multipurpose Baby bed, on the fence of tailstock portion, be installed with the sleeve 31 that oral area upwards arranges, in sleeve, be fitted with can only with the sleeve support bar that Shang Xia 31, plug-in mounting coordinates 32, support bar can not rotate relative to sleeve in sleeve, while rocking control bed board with controller before and after like this, support bar rocks before and after also must be thereupon.Post upper is installed with trunnion axis 33, trunnion axis be not only horizontally disposed with and also trunnion axis along bed board horizontally set.On trunnion axis, be set with pivoted housing 34, pivoted housing can rotate around trunnion axis, is installed with the fork 35 to downward-extension on pivoted housing.When roars of laughter child amusement, bed board rocks before and after under controller is controlled, and now pivoted housing is because its outside is installed with fork and causes bias or lay particular stress on, so fork also can swing centered by trunnion axis thereupon.Drive bevel gear 45 is installed on pivoted housing, and drive bevel gear and pivoted housing coaxially arrange.When pivoted housing rotates, drive bevel gear is also inevitable synchronously rotates thereupon.

Trunnion axis end is supported a riser 37 is installed by connecting rod 43, and riser vertically arranges, and is arranged to head-shaped with apish " head ".Riser top is provided with two spaced through holes 38, and this through hole is equivalent to " eye socket " of " head ".The interior vertical axis 39 by vertical setting of through hole is hinged with and turns ball 40, and turning ball can rotate around vertical axis, turns " eyeball " or " eyeball " that ball is equivalent to eyes.For convenience of narration, by turning ball one end towards head of a bed portion, be called front end or front side or outside or outer end, the other end is called to rear end rear side or inner side or the inner.Turn ball inner side and be installed with swing arm 41, settings that stretch out of swing arm Cong Zhuan ball center, generally extends setting towards trunnion axis.Between two swing arms, be connected with tooth bar 42, the flank of tooth of tooth bar arranges upward, and tooth bar two ends are corresponding hinged with two swing arm ends by the hinge vertically arranging respectively.Such two swing arms or two turn ball and just by rack-driving, link together, and can realize the interlock between three.Connecting rod middle part is rotatablely equipped with rotating shaft 44, and rotating shaft one end is provided with the driven wheel of differential 46 with drive bevel gear engagement, and the rotating shaft other end is provided with and tooth bar meshed gears 36.Pivoted housing will move by drive bevel gear, driven wheel of differential, rotating shaft and gear driving rack successively like this, and namely driving turns ball rotates around vertical axis, has also just been equivalent to the action of " eyeball stravismus " or " pearl in an instant ".When pivoted housing rotates backward, " eyeball " oppositely looked side ways or reverse " pearl in an instant ".Like this, along with rock the front and back of bed board, pivoted housing comes and goes and rotates, " eyeball " also just swings, and not only can play the effect of amusing baby, can also attract baby's notice, guide its swing of thinking deeply object, rotation etc. naturally to imagine, help lend some impetus to its intelligence development.Because the action of " pearl in an instant " is rotational action and is driven by the engagement of each gear therefore almost there is no noise, when baby need to sleep, can be on baby's impact of being burdened with, certain, also can directly support bar be extracted in sleeve, operate very simple.

In the present embodiment, turn ball and be pasted with color chips 47 towards a side of head of a bed portion.In the outer end that turns ball, stick after color chips, make " eyeball " more vivid, more true to nature, contribute to attract and amuse baby.

On front hydraulic cylinder outer wall, be installed with the front limit bar 18 extending to front-wheel, front hydraulic stem middle part is installed with the front triggering block 23 that extend at gag lever post middle part forward, front limit bar two ends are provided with the front limit switch 24 corresponding with front triggering block, and front limit switch series is connected in the current supply circuit of motor.

On rear hydraulic cylinder outer wall, be installed with the rear gag lever post 28 extending to trailing wheel, rear hydraulic stem middle part is installed with the rear triggering block 29 that extend at gag lever post middle part backward, rear gag lever post two ends are provided with the rear limit switch 30 corresponding with rear triggering block, and rear limit switch is serially connected in the current supply circuit of motor.

In the present embodiment, hydraulic means claims again hydraulic mechanism or hydraulic system, and in different documents, title may be slightly variant.Hydraulic means, battery, motor, each hydraulic cylinder and hydraulic stem are all the universal products of market purchasing, and its structure and operation principle belong to known technology, and therefore innovation that neither the art of this patent will not carefully be stated at this.

Claims

1. multipurpose Baby bed, comprise bed board (1), bed board (1) end face surrounding is installed with fence (8), it is characterized in that: bed board (1) front part sides is installed with respectively front hydraulic cylinder (2), front hydraulic stem (3) lower end of front hydraulic cylinder (2) is provided with front-wheel (4), bed board (1) both sides, rear portion are installed with respectively rear hydraulic cylinder (5), rear hydraulic stem (6) lower end of rear hydraulic cylinder (5) is provided with trailing wheel (7), bed board (1) bottom is provided with battery (11) and the motor (12) being electrically connected, and the hydraulic means (13) being driven by motor (12), the output of hydraulic means (13) is connected with rear hydraulic cylinder (5) with front hydraulic cylinder (2) by control valve (14) respectively and drives its expanding-contracting action, also comprise the controller (9) of controlling motor (12) work and drive control valve action, described control valve (14) comprises controls the front transfer valve (15) that front hydraulic cylinder (2) expanding-contracting action switches, control hydraulic means (13) the front stop valve (16) of hydraulic cylinder (2) oil supply loop break-make forward, the rear transfer valve (19) that after controlling, hydraulic cylinder (5) expanding-contracting action switches, control hydraulic means (13) the rear stop valve (20) of hydraulic cylinder (5) oil supply loop break-make backward, described controller (9) comprises base (10), the front switching push button (21) of transfer valve (15) action before base (10) is provided with and controls, the front cut-off button (22) of stop valve (16) action before controlling, the rear switching push button (25) of transfer valve (19) action after controlling, the rear cut-off button (26) of stop valve (20) action after controlling, also comprise the start button (27) being serially connected in motor (12) electric power loop, on base (10), be hinged with pedal (17), interference fit is pressed with front switching push button (21) and rear switching push button (25) respectively in pedal (17) two ends, on the fence of tailstock portion (8), be installed with sleeve (31), in sleeve (31), be fitted with upwardly extending support bar (32), support bar (32) upper end is installed with the trunnion axis (33) laterally be arrangeding in parallel with bed board, trunnion axis (33) middle part is set with the pivoted housing (34) that can rotate around trunnion axis (33), on pivoted housing (34), be installed with the fork (35) to downward-extension, on pivoted housing (34), be coaxially installed with drive bevel gear (45), trunnion axis (33) end is fixed with head-shaped riser (37) by the connecting rod (43) extending to head of a bed portion, riser (37) top is provided with the through hole (38) that two horizontal intervals arrange, in through hole (38), by vertical axis (39), be hinged with and turn ball (40), rotating shaft (40) is installed with swing arm (41) near a side of trunnion axis (33), also comprise the two ends tooth bar (42) hinged with two swing arms (41) end respectively, connecting rod (43) middle part is provided with rotating shaft (44), rotating shaft (44) one end is installed with the driven wheel of differential (46) with drive bevel gear (45) engagement, rotating shaft (44) other end is installed with and tooth bar (42) meshed gears (36).

2. multipurpose Baby bed as claimed in claim 1, is characterized in that: turn ball (40) and be pasted with color chips (47) towards a side of head of a bed portion.

3. multipurpose Baby bed as claimed in claim 2, it is characterized in that: on front hydraulic cylinder (2) outer wall, be installed with the front limit bar (18) extending to front-wheel (4), front hydraulic stem (3) middle part is installed with the front triggering block (23) that extend at gag lever post (18) middle part forward, front limit bar (18) two ends are provided with the front limit switch (24) corresponding with front triggering block (23), and front limit switch (24) is serially connected in the current supply circuit of motor (12).

4. multipurpose Baby bed as claimed in claim 3, it is characterized in that: on rear hydraulic cylinder (5) outer wall, be installed with the rear gag lever post (28) extending to trailing wheel (7), rear hydraulic stem (3) middle part is installed with the rear triggering block (29) that extend at gag lever post (28) middle part backward, rear gag lever post (28) two ends are provided with the rear limit switch (30) corresponding with rear triggering block (29), and rear limit switch (30) is serially connected in the current supply circuit of motor (12).