CN111038563A

CN111038563A - Four-wheel folding handcart

Info

Publication number: CN111038563A
Application number: CN201911360276.XA
Authority: CN
Inventors: 邓建文
Original assignee: Wen Fa Wang
Current assignee: Wen Fa Wang
Priority date: 2019-12-25
Filing date: 2019-12-25
Publication date: 2020-04-21

Abstract

The invention discloses a four-wheel folding trolley, which comprises a carrying support for bearing an object and a pushing hand which is connected with the carrying support through a hinged support and can be folded on the carrying support, wherein the carrying support comprises two parallel barrel rods, trundles for supporting the support are sleeved on the barrel rods, the tail ends of the barrel rods are connected with the hinged support through fulcrums, transmission pipes are arranged in the barrel rods, rotating external members which can be sleeved on the barrel rods are fixedly connected to the trundles, spiral hollow rails are arranged on the inner walls of the rotating external members, and first lock pins which are clamped and embedded in the hollow rails are arranged on the transmission pipes; the two sides of the hinged support are provided with curved sliding chutes, and the end part of the transmission pipe is provided with a pin column which is clamped in the curved sliding chutes and can slide in the curved sliding chutes; the pushing handle is folded. The multiple positioning devices are arranged in the luggage van, and after the luggage van is opened, all parts of the luggage van are stably and reliably connected, so that the luggage van cannot shake forwards and backwards or leftwards and rightwards. And the luggage barrow with the foldable caster wheels and the foldable push handle has small volume and convenient carrying.

Description

Four-wheel folding handcart

Technical Field

The invention relates to the technical field of carrying equipment, in particular to a four-wheel folding trolley.

Background

At present, the existing hand-push luggage cart is composed of a push handle, a support and trundles, wheels are arranged below the support, the push handle is arranged on the support and is level with the waist of a person, the structure is simple, the size is large, and the carrying is inconvenient.

However, some foldable luggage carts only fold the pushing handle into the side of the rack, and the pushing handle can not fold the caster into the rack at the same time when being folded on the rack, so that the volume of the foldable luggage carts can not be minimized. In addition, there is also a structure in which the caster is folded in the holder at the same time when the pusher is folded into the holder side by gear transmission, but in this structure, the pusher swings back and forth or left and right after being opened due to the transmission of the rack, so that the rack cannot be engaged reliably, and the rack is easily damaged.

Disclosure of Invention

The invention aims to solve the problems that in the prior art, a pushing hand swings back and forth or left and right, so that tooth plates cannot be reliably meshed, and the tooth plates are easy to damage.

In order to achieve the purpose, the invention adopts the following technical scheme:

the four-wheel folding trolley comprises a carrying support for bearing an object and a pushing hand which is connected with the carrying support through a hinged support and can be folded on the carrying support, wherein the carrying support comprises two parallel barrel rods, trundles for supporting the support are sleeved on the barrel rods, the tail ends of the barrel rods are connected with the hinged support through pivots, transmission pipes are arranged in the barrel rods, rotating external members which can be sleeved on the barrel rods are fixedly connected to the trundles, spiral hollow rails are arranged on the inner walls of the rotating external members, and first lock pins which are clamped and embedded in the hollow rails are arranged on the transmission pipes; the two sides of the hinged support are provided with curved sliding chutes, and the end part of the transmission pipe is provided with a pin column which is clamped in the curved sliding chutes and can slide in the curved sliding chutes; when the pushing handle is folded, the bent arc-shaped sliding groove of the hinged support pushes the pin column and the transmission pipe to move horizontally, the first locking pin on the transmission pipe drives the rotating external member to rotate around the cylinder rod, and the trundles connected with the rotating external member automatically fold towards the support synchronously.

Preferably, the tail part of the spiral hollow track of the rotating sleeve member is provided with a straight groove, and when the pushing handle is rotated to be opened to enable the first locking pin to drive the rotating sleeve member to rotate excessively, the first locking pin is clamped in the straight groove on the rotating sleeve member to be locked.

Preferably, a clamping groove is formed in one end, far away from the hinged support, of the rotating sleeve, a corresponding second lock pin is arranged on the transmission pipe, the second lock pin and the first lock pin are mutually staggered in the axial direction and the radial direction of the transmission pipe, and when the rotating sleeve is driven to rotate downwards excessively by the first lock pin, the second lock pin is clamped into the clamping groove in the rotating sleeve to be locked.

Preferably, the push handle comprises an inner telescopic sleeve, an outer telescopic sleeve and a telescopic locking mechanism, and an automatic lock mechanism which is linked with the telescopic locking mechanism and prevents the hinge base from rotating around the pin when the push handle is in an open state is arranged in the hinge base.

Preferably, the automatic lock mechanism comprises an L-shaped lock seat, two side faces of the lock seat are provided with chutes, the lower part of the lock seat and the hinged support form a movable connection only having freedom degree of movement along the axial direction of the transmission pipe, a lock column penetrating through the chutes on the lock seat is connected with the transmission plate, and the transmission plate is movably connected with the outer sleeve and driven by the inner sleeve to move in the outer sleeve; when the push handle is in an open state, the pin column is clamped at the L-shaped corner of the lock seat;

preferably, the outer sleeve is also internally provided with a limiting strip, the upper end of the limiting strip is provided with a limiting lug, the lower end of the limiting strip penetrates through the through hole at the bottom of the inner sleeve and then is connected with the transmission plate, and the upper end of the limiting strip is movably connected with the inner sleeve through the limiting lug;

preferably, the transmission plate is arranged on a seat provided with a through hole, the seat is fixed at the lower end part of the outer sleeve, the transmission plate slides up and down along the through hole on the seat, the upper part of the transmission plate is provided with a pre-pressing spring and a connecting seat, and the connecting seat is connected with the lower end of the limiting strip;

preferably, the rotating sleeve is formed by combining a rotating sleeve c and rotating seats a and b with symmetrical spiral grooves, and the rotating seats a and b are inserted into the rotating sleeve c after being combined; the symmetrical spiral grooves on the rotary seats a and b are combined into a spiral hollow track;

preferably, the telescopic locking mechanism is arranged in a cross bar connected with the outer sleeve, and the telescopic locking mechanism at least comprises two inner locking pins, an outer sleeve, opposite bolts, a handle connected with the bolts and a spring arranged between the two bolts; the front end of the handle is provided with a convex hook a; the bracket is provided with a panel, the panel is provided with a bayonet a clamped with the convex hook a, and the position of the bayonet a corresponds to the position of the handle when the push handle is folded on the panel;

preferably, the front end of the bottom of the hinged support is provided with a notch, the end surface of the rotating sleeve corresponding to the notch is provided with a lug, and when the caster is opened, the lug is clamped in the notch on the hinged support.

Has the advantages that:

1. according to the invention, a transmission pipe with a first lock pin, a second lock pin and a pin column is arranged in a luggage carrier bracket, a caster wheel with a rotating external member is sleeved outside the transmission pipe, and the first lock pin of the transmission pipe slides on a spiral hollow track arranged on the rotating external member; the pin column slides in the curved chute of the hinged support connecting the bracket and the push handle and is locked by the lock base;

2. according to the invention, by releasing the locking of the lock seat, when the push handle is folded or unfolded, the transmission pipe is forced to move, and the spiral hollow track of the rotating sleeve part rotates around the lock pin relatively, so that all the trundles are automatically folded on the luggage cart carrying support when the push handle is folded;

3. the luggage barrow is internally provided with multiple positioning devices, and after the luggage barrow is opened, all parts of the luggage barrow are stably and reliably connected, so that the luggage barrow cannot shake forwards and backwards or leftwards and rightwards. And the luggage barrow with the foldable caster wheels and the foldable push handle has small volume and convenient carrying.

Drawings

FIG. 1 is a schematic view of the luggage cart of the present invention;

FIG. 2 is a cross-sectional view of FIG. 1;

FIG. 3 is a front view of the cross-bar of FIG. 1;

FIG. 4 is a structural view of a luggage cart according to another embodiment of the present invention;

FIG. 5 is an enlarged exploded view of a portion of FIG. 4;

FIG. 6 is a structural view of the pushing handle of FIG. 4 with the inner sleeve retracted to the outer sleeve;

fig. 7 is a structural view of the push handle in fig. 6 during the rotating folding process;

FIG. 8 is the structural view of FIG. 7 fully collapsed above the frame;

FIG. 9 is an exploded perspective view of the luggage cart of FIG. 4;

FIG. 10 is another exploded perspective view of the luggage cart of FIG. 4;

FIG. 11 is a-e views of various angles of the rotating sleeve;

FIG. 12 is a perspective view of the luggage cart of FIG. 4 after being stowed;

FIG. 13 is a cross-sectional view of the push-to-retract;

FIG. 14 is a perspective view of the luggage cart as a whole;

fig. 15 is a perspective view of the flatbed fully collapsed.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments.

Referring to fig. 1-15, the four-wheeled folding handcart comprises a carrying support 1 for carrying objects and a pushing handle 2 connected with the carrying support through a hinged support 7 and foldable on the carrying support, the carrying support comprises two parallel cylinder rods 11 and a plurality of cross bars 13, the cylinder rods 11 are sleeved with caster wheels 3 for supporting the support, and the tail ends of the cylinder rods 11 are connected with the hinged support 7 through a pivot 0. The pushing handle 2 comprises telescopic inner and

outer sleeves

21, 22, a cross bar 23 connecting the left and right outer sleeves 22 and a telescopic locking mechanism 9 arranged in the cross bar 23. A transmission pipe 5 is arranged in the cylinder rod 11, a rotating external member 4 which can be sleeved on the cylinder rod 11 is fixedly connected to the caster wheel 3, symmetrical spiral hollow tracks 41 are arranged on the inner wall of the rotating external member 4, and first lock pins (vertical lock pins) 51 which are embedded in the hollow tracks in a clamping mode are arranged on the transmission pipe 5. The two sides of the hinged support 7 are provided with a curved chute 6, and the end part of the transmission tube 5 is provided with a pin 8 which is clamped in the curved chute 6 and can slide in the chute. An automatic locking mechanism 15 which is linked with the telescopic locking mechanism 9 and prevents the hinged support 7 from rotating around the pin 8 when the push handle 2 is opened and/or folded is arranged in the hinged support 7. When the pushing handle 2 is folded onto the support in a rotating manner, the curved sliding groove 6 of the hinged support 7 pushes the pin 8 and the transmission pipe 5 to move horizontally, the first locking pin 51 on the transmission pipe 5 drives the rotating sleeve 4 to rotate around the cylinder rod 11, and the caster 3 connected with the rotating sleeve 4 automatically folds towards the support 1 synchronously.

In the present embodiment, in order to position the caster 3 when the caster 3 is opened around the barrel rod 11, the straight groove 42 is opened at the tail of the spiral hollow track 41 of the rotation set 4, and when the pushing handle 2 is rotated and opened until the rotation set 4 is rotated by 90 degrees under the driving of the first lock pin 51, the first lock pin 51 is locked by being snapped into the straight groove 42 on the rotation set 4. The specific structure of the rotating sleeve 4 is shown in fig. 11: wherein, the figure (a) shows that the rotating sleeve 4 is formed by combining rotating

seats

4a and 4b with symmetrical spiral grooves, the rotating

seats

4a and 4b are inserted into a rotating seat sleeve 4c after being combined, and are respectively fixedly connected with the rotating seat sleeve 4c through fasteners; FIG. (b) is a schematic view showing the rotating sleeve 4 with a part of the outer layer of the rotating sleeve 4c cut away in the axial direction; FIG. (c) is a perspective view showing another direction of FIG. (b); FIG. (d) is a front view of FIG. (c); FIG. (e) is a side view of FIG. (d). Meanwhile, as shown in fig. 9, in order to facilitate the first lock pin 51 to follow the movement of the driving pipe 5, the cylinder rod 11 is provided with a corresponding opening 11 b.

In this embodiment, the luggage cart in fig. 1 to 3 is specially designed with a lateral positioning device of the caster 3, which includes a second locking pin 52 disposed on the transmission tube 5, and a corresponding locking slot 43 disposed on the rotation sleeve 4. As shown in fig. 2 and 11, the second lock pin 52 is transversely mounted on the driving pipe, and thus may be referred to as a transverse lock pin, and the second lock pin 52 is offset from the first lock pin by a certain distance and perpendicular to the first lock pin. When the rotation set 4 is rotated through 90 degrees by the driving of the first lock pin 51, the second lock pin 52 is locked in the lock slot 43 on the rotation set 4. To facilitate the movement of the second locking pin, a corresponding opening 13a should be provided in the cross bar 13 of the bracket 1. At the same time, as shown in fig. 9, a corresponding opening 11a should also be provided in the bobbin 11.

In this embodiment, as shown in fig. 4, the automatic locking mechanism 15 includes an L-shaped lock seat 151, two side surfaces of the lock seat 151 are provided with inclined slots 150, a lower portion of the lock seat 151 is fitted in a sliding slot 71 at the bottom of the hinge base 7, and the self-locking seat 151 can slide back and forth along the sliding slot 71 to form a movable connection having only freedom of movement along the axial direction of the transmission pipe 5. A lock cylinder 152 passing through the inclined groove 150 of the lock holder 151 is connected to the driving plate 153.

In this embodiment, the driving plate is mounted on a seat 154 having a through hole, the seat 154 is fixed at the lower end of the outer sleeve 22, the driving plate 153 can slide up and down along the through hole of the seat 154, and the upper portion thereof is connected to a limit bar 157 through a spring 155 and a connecting seat 156 to form a normal linkage mechanism that automatically pushes up (pops up). The spring 155 is installed between the seat 154 and the connecting seat 156, and under the action of the seat 154 and the connecting seat 156, the driving plate 153 is moved upward by the force of the spring 155 in a normal state, and the lock seat 151 moves forward under the action of the pin 152, the driving plate 153 and the inclined slot 150, that is, the lock seat 151 is in a locked position in a normal state (as shown in fig. 4). In the process that the pushing handle 2 is rotated and opened from the folded state, the pin 8 moves in the curved sliding groove 6 to automatically push the locking seat 151 to move backwards, when the pushing handle is in the completely opened state, the locking seat 151 moves forwards under the action of the spring 155, the pin 8 is clamped at the L-shaped corner of the locking seat 151, namely, the hinged support 7 and the pushing handle 2 connected with the hinged support are fixed under the action of the fulcrum 0 and the pin 8, the hinged support 7 cannot rotate around the fulcrum 0, and the pushing handle 2 and the bracket 1 are kept in rigid connection.

In this embodiment, the upper end of the limiting strip 15 is provided with a limiting lug 00, the lower end of the limiting strip 157 passes through the through hole on the inner plug 21a at the bottom of the inner sleeve 21 and then is indirectly connected with the driving plate 153, and the upper end forms a movable connection with the inner sleeve 21 through the limiting lug 00. The limiting lug 00 has the following functions: when the hand 2 is rotated and opened, the inner sleeve 21 moves upwards, the inner plug 22a connected to the lower end part of the inner sleeve moves upwards at the same time, when the inner sleeve 21 and the outer sleeve 21 are locked by the telescopic locking mechanism 9 when the hand rises to the working height, the driving plate 153 cannot move downwards under the blocking action of the limiting lugs 00 of the limiting strips 157, so that the lock seat 151 cannot move backwards, namely, the lock seat 6 locks the pin 8 at the L-shaped corner, and the hinge seat 7 is in a safe locking state.

In this embodiment, as shown in fig. 13, the telescopic locking mechanism 9 is disposed in the cross bar 23 connected to the outer sleeve 22, and the telescopic locking mechanism at least includes two pins 91 for locking the relative positions of the inner and

outer sleeves

21, 22, a handle 92 connected to the pins 91, and a spring 93 disposed between the two pins 91; the front end of the handle 92 is provided with a protruding hook 92 a. As shown in fig. 14 and 15, the bracket 1 is provided with a panel 12, the panel 12 is provided with a bayonet 12a engaged with the hook 92a, and the position of the bayonet 12a corresponds to the position of the handle 92 when the push handle 2 is folded on the panel 12. Thus, when the luggage barrow is folded, the push handle 2, the bracket 1, the panel 12 and the caster 3 can be connected into a whole through the convex hook 92.

In the present embodiment, the positioning of the caster 3 is also enhanced by the following modification. As shown in fig. 7, 11 and 12, the front end of the bottom of the hinge base 7 is provided with a notch 10, the end surface of the rotating sleeve 4 corresponding to the notch 10 is provided with a lug 44, when the caster wheel 3 is opened, the lug 44 is just locked in the notch 10 on the hinge base 7, wherein the shape of the lug 44 and the notch 10 can be trapezoidal or other shapes. The lug 44 is beneficial to fastening the connection between the caster 3 and the bracket 1 when the pushing handle 2 is in the unfolding state, preventing the caster 3 from loosening, and avoiding the phenomenon that the pushing handle 2 is folded to the object carrying bracket 1 due to the overweight of the caster 3 in loading.

In this embodiment, the number of the spiral hollow tracks 41 in the rotating sleeve 4 is two, and the two spiral hollow tracks are axially symmetrically arranged inside the rotating sleeve 4, and the driving tube 5 is provided with the first locking pins 51 corresponding to the number of the spiral hollow tracks 41, and respectively embedded in the corresponding spiral hollow tracks 41.

In this embodiment, two curved chutes 6 are provided on the hinge base 7, and are respectively provided on both sides of the hinge base 7; the number of the pins 8 corresponding to the curved sliding grooves 6 is also two, and the pins are respectively clamped in the corresponding curved sliding grooves 8.

Of course, the luggage carrier 1 may not be provided with the loading panel 12 or the like according to the different requirements of each user.

As shown in fig. 4, 6 to 8, the general work flow of the luggage cart in this embodiment is as follows:

in this embodiment, when the cart is in the working state shown in fig. 4, the caster 3 and the pushing handle 2 are both in the open state, the first lock pin 51 on the driving tube 5 is locked in the straight groove 42 on the rotating sleeve 4, the second lock pin 52 is locked in the locking groove 43 on the rotating sleeve 4, the lug 44 on the rotating sleeve 4 is mutually locked with the notch 10 on the hinge base 7, and the pin 8 is locked at the L-shaped corner of the lock base 151, so that the hinge base 7 cannot rotate around the fulcrum 0. And the driving plate 153 of the automatic locking mechanism 15 can not move downwards under the combined action of the pushing handle telescopic locking device 9 and the limiting lug 00 on the limiting strip 157, so that the lock seat 151 can not move backwards along the axial direction of the driving pipe 5, and a stable connection among the pushing handle 2, the bracket 1 and the caster 3 is ensured to be formed in an opening state.

In this embodiment, when the handle 2 needs to be rotated and folded above the luggage carrier 1, the telescopic locking mechanism 9 of the inner and

outer sleeves

21, 22 is first released, and the inner sleeve 21 is retracted downward. As shown in fig. 6, when a force from the bottom of the inner sleeve 21 acts on the driving plate 153, the locking seat 151 moves backward by the cooperation of the locking pin 152 on the driving plate 153 and the inclined groove 150, so that the pin 8 on the driving tube 5 is separated from the L-shaped corner of the locking seat 151, and the locking of the hinge seat 7 by the locking seat 151 is released. At this time, when the pushing handle 2 is pressed towards the carrier support 1, as shown in fig. 7, the lug 44 on the rotating sleeve member 4 is disengaged from the notch 10 on the hinged support 7, the pin 8 at the end of the driving tube 5 slides in the curved sliding slot 6 of the hinged support 7, so that while pushing the pushing handle 2, the hinged support 7 presses the driving tube 5 to move forward, the second lock pin 52 is disengaged from the slot 43, the first lock pin 51 is disengaged from the straight slot 42, and at the same time, because the first lock pin 51 on the driving tube 5 is engaged with the spiral hollow track 41 of the rotating sleeve member 4, when the driving tube 5 continues to be forced to move forward, the spiral hollow track 41 of the rotating sleeve member 4 rotates around the first lock pin 51, so that the pushing handle 2 pushes the driving tube 5 to rotate the caster 3 connected to the rotating sleeve member 4, thereby realizing that the caster 3 is automatically folded under the luggage carrier support 1 when the pushing handle 2 is folded. The pre-pressing spring 155 is used to automatically move the lock seat 151 forward under the action of the spring 155 when the push tube 2 rotates downward to a certain angle and the force pressing on the push tube 2 is released. Upon opening, the lock housing 151 automatically moves rearward under the force of the pin 8.

The working process of opening the luggage van is reverse to the above process.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered to be within the technical scope of the present invention, and the technical solutions and the inventive concepts thereof according to the present invention should be equivalent or changed within the scope of the present invention.

Claims

1. Folding handcart of four-wheel, including what be used for bearing the weight of the article carries thing support (1) and through hinged-seat (7) connect and can fold pushing hands (2) on carrying the thing support, carry the thing support and include two parallel barrel bars (11), the cover is equipped with truckle (3) that are used for supporting the support on barrel bar (11), the end of barrel bar (11) is connected its characterized in that through fulcrum (0) and hinged-seat (7): a transmission pipe (5) is arranged in the cylinder rod (11), a rotating external member (4) which can be sleeved on the cylinder rod (11) is fixedly connected to the caster (3), a spiral hollow track (41) is arranged on the inner wall of the rotating external member, and a first lock pin (51) which is clamped and embedded in the hollow track is arranged on the transmission pipe (5); the two sides of the hinged support (7) are provided with curved sliding chutes (6), and the end part of the transmission pipe (5) is provided with a pin column (8) which is clamped in the curved sliding chutes (6) and can slide in the sliding chutes; when the pushing handle (2) is folded, the bent arc-shaped sliding groove (6) of the hinged support (7) pushes the pin column (8) and the transmission pipe (5) to move horizontally, the first lock pin (51) on the transmission pipe (5) drives the rotating sleeve piece (4) to rotate around the cylinder rod (11), and the caster wheel (3) connected with the rotating sleeve piece (4) automatically folds towards the support (1) synchronously.

2. A four-wheeled folding cart according to claim 1, wherein: the tail of the spiral hollow track (41) of the rotating sleeve member (4) is provided with a straight groove (42), and when the pushing handle (2) is rotated to be opened to enable the first lock pin (51) to drive the rotating sleeve member (4) to rotate by 90 degrees, the first lock pin (51) is clamped into the straight groove (42) on the rotating sleeve member (4) to be locked.

3. A four-wheeled folding cart according to claim 2, wherein: one end, far away from the hinged support (7), of the rotating sleeve member (4) is provided with a clamping groove (43), the transmission pipe (5) is provided with a corresponding second lock pin (52), the second lock pin (52) and the first lock pin (51) are staggered in the axial direction and the radial direction of the transmission pipe (5), and when the rotating sleeve member (4) rotates by 90 degrees under the driving of the first lock pin (51), the second lock pin (52) is clamped into the clamping groove (43) on the rotating sleeve member (4) to be locked.

4. A four-wheeled folding cart according to claim 3, wherein: the push handle (2) comprises an inner telescopic sleeve, an outer telescopic sleeve (21, 22) and a telescopic locking mechanism, wherein an automatic lock mechanism (15) which is linked with the telescopic locking mechanism and prevents the hinged support (7) from rotating around the pin column (8) in the opening state of the push handle (2) is arranged in the hinged support (7).

5. The four-wheeled folding cart of claim 4, wherein: the automatic lock mechanism (15) comprises an L-shaped lock seat (151), inclined grooves (150) are formed in two side faces of the lock seat (151), the lower portion of the lock seat (151) and the hinged support (7) form movable connection only with freedom degree of axial movement along the transmission pipe (5), a lock column (152) penetrating through the inclined grooves (150) in the lock seat (151) is connected with a transmission plate (153), and the transmission plate (153) is movably connected with the outer sleeve (22) and driven by the inner sleeve (21) to move in the outer sleeve (22); when the push handle (2) is in an open state, the pin column (8) is locked at the L-shaped corner of the lock seat (151).

6. The four-wheeled folding cart of claim 5, wherein: the outer sleeve is also internally provided with a limiting strip (157), the upper end of the limiting strip (157) is provided with a limiting lug (00), the lower end of the limiting strip (157) penetrates through the through hole at the bottom of the inner sleeve (21) and then is connected with the transmission plate (153), and the upper end of the limiting strip is movably connected with the inner sleeve (21) through the limiting lug (00).

7. The four-wheeled folding cart of claim 6, wherein: the transmission plate (153) is arranged on a seat (154) provided with a through hole, the seat (154) is fixed at the lower end part of the outer sleeve (22), the transmission plate (153) slides up and down along the through hole on the seat (154), a pre-pressing spring (155) and a connecting seat (156) are arranged at the upper part of the transmission plate (153), and the connecting seat (156) is connected with the lower end of the limit strip (157).

8. The four-wheeled folding cart of claim 4, wherein: the rotary sleeve (4) is formed by combining a rotary seat sleeve (4c) and rotary seats (4a and 4b) with symmetrical spiral grooves, and the rotary seats (4a and 4b) are inserted into the rotary seat sleeve (4c) after being combined; the symmetrical spiral grooves on the rotary seats (4a, 4b) are combined into a spiral hollow track (41).

9. The four-wheeled folding cart of claim 4, wherein: the telescopic locking mechanism (9) is arranged in a cross bar (23) connected with the outer sleeve (22), and at least comprises two bolts (91) for locking the relative positions of the inner sleeve (21) and the outer sleeve (22), a handle (92) connected with the bolts (91) and a spring (93) arranged between the two bolts (91); the front end of the handle (92) is provided with a convex hook (92 a); the support (1) is provided with a panel (12), the panel (12) is provided with a bayonet (12a) clamped with the convex hook (92a), and the position of the bayonet (12a) corresponds to the position of the handle (92) when the push handle (2) is folded to the panel (12).

10. The four-wheeled folding cart of claim 4, wherein: the front end of the bottom of the hinged support (7) is provided with a notch (10), the end face, corresponding to the notch (10), of the rotating sleeve (4) is provided with a lug (44), and when the caster wheel (3) is opened, the lug (44) is clamped in the notch (10) in the hinged support (7).