CN223812610U

CN223812610U - Vehicle

Info

Publication number: CN223812610U
Application number: CN202421785599.XU
Authority: CN
Inventors: 俞学明; 李照国; 周志华
Original assignee: Goodbaby Child Products Co Ltd
Current assignee: Goodbaby Child Products Co Ltd
Priority date: 2024-07-26
Filing date: 2024-07-26
Publication date: 2026-01-20
Anticipated expiration: 2034-07-26

Abstract

The utility model relates to a carrier, which comprises a bottom supporting mechanism and a bearing device, wherein the bottom supporting mechanism comprises a mounting seat and a supporting seat, the mounting seat is arranged to extend along the left-right direction, the supporting seat is arranged on the mounting seat, the bearing device comprises a seat, the seat is connected with the supporting seat in a relative rotating way around a seat rotating shaft, the seat rotating shaft extends along the left-right direction, the seat rotating shaft is arranged at a position, close to one end part of the supporting seat in the front-rear direction, of the supporting seat, when the carrier is folded, the seat is overturned around the seat rotating shaft and is folded towards the bottom supporting mechanism, so that the bearing device does not need to be detached and singly folded for storage, the problem that the bearing device is too large in size and inconvenient to store due to folding along with the bottom supporting mechanism is avoided, and convenience is brought to daily use of a user.

Description

Carrier tool

Technical Field

The present utility model relates to a carrier.

Background

In the prior art, some carriers such as a baby stroller can be used in a reversing manner, so that the facing direction of a child sitting on the seat can be switched. The seat pocket can be installed on the support of the carrier in a detachable mode, and the orientation of the seat pocket is changed through forward installation or reverse installation, but the child needs to be moved out of the seat pocket before operation, so that the operation is complicated. In order to avoid the need to shift out children, the rotation axis is installed through the seat bottom of seat pocket on some carriers for realize the switching-over when seat pocket device is rotatory around this rotation axis, but this structure makes when folding the carrier, and the seat pocket can't draw in with the carrier support effectively, needs to pull down the seat pocket and fold alone and deposit, leads to folding operation and accomodate all comparatively loaded down with trivial details, causes the use inconvenient.

Disclosure of utility model

The present utility model is directed to a carrier that obviates one or more problems in the prior art.

In order to achieve the above purpose, the utility model adopts the following technical scheme:

A carrier having an unfolded state and a folded state, the carrier comprising:

The bottom supporting mechanism comprises a mounting seat and a supporting seat, wherein the mounting seat is arranged in a manner of extending along the left-right direction, and the supporting seat is arranged on the mounting seat;

The bearing device comprises a seat, the seat is connected with the supporting seat in a relative rotating way around a seat rotating shaft, the seat rotating shaft extends along the left-right direction, and the seat rotating shaft is arranged at a position of the supporting seat close to one end part in the front-rear direction;

When the carrier is folded, the seat turns around the seat rotating shaft and is closed and folded towards the bottom supporting mechanism.

In some embodiments, the support base is rotatably mounted on the mounting base around a support base rotation shaft, and the support base rotation shaft is disposed in an extending manner along a vertical direction.

In some embodiments, the carrier further includes a locking structure for locking the seat to the support base, the locking structure being provided at a position of the support base near the other end portion in the front-rear direction.

In some embodiments, the locking structure includes a locking groove provided on one of the seat and the support base and a locking piece engaged with the locking groove, the locking piece being movably provided on the other of the seat and the support base.

In some embodiments, the seat has a first end and a second end which are respectively disposed at two different ends in a length direction of the seat, the first end and one end of the supporting seat are rotatably connected around the seat rotating shaft, the second end and the supporting seat are detachably disposed, and the locking structure is disposed between the second end and the other end of the supporting seat.

In some embodiments, the locking piece is movably arranged on the second end portion, the locking groove is arranged on the supporting seat, an unlocking piece is movably arranged on the second end portion, and the unlocking piece is connected with the locking piece so as to drive the locking piece to move and be separated from being matched with the locking groove.

In some embodiments, the bottom support mechanism includes a first support and a second support, an upper portion of the first support is rotatably connected with an upper portion of the second support, the mounting seat is fixedly arranged on the upper portion of the first support, the carrier is in a folded state, the first support and the second support are mutually folded, and the seat and the first support or the second support are mutually folded.

In some embodiments, the carrying device further comprises a backrest rotatably connected with the seat, the carrier is in a folded state, the backrest is folded on one side of the seat, and the bottom support mechanism is folded on the other side of the seat.

In some embodiments, the carrier further comprises a push rod frame, the lower part of the push rod frame is rotatably connected to the supporting seat, and when the carrier is folded, the push rod frame turns forwards or backwards to be folded with the bottom supporting mechanism.

In some embodiments, the carrier is a cart, the bottom support mechanism includes a first support and a second support, an upper portion of the first support is rotatably connected with an upper portion of the second support, a first wheel assembly is disposed at a lower portion of the first support, a second wheel assembly is disposed at a lower portion of the second support, and the mounting seat is fixedly disposed at an upper portion of the first support.

Compared with the prior art, the carrier provided by the utility model has the advantages that the seat can rotate relative to the supporting seat and is folded together with the bottom supporting mechanism along the front-back direction, so that the carrying device does not need to be disassembled and independently folded for storage, the problem that the carrying device is too large in size and inconvenient to store due to folding along with the bottom supporting mechanism is avoided, and convenience is brought to daily use of users.

Drawings

Fig. 1 is a schematic perspective view of a carrier in an unfolded state, in which a carrying device is in a forward position;

FIG. 2 is a schematic side view of the carrier of FIG. 1;

FIG. 3 is a schematic perspective view of the carrier of FIG. 1 after the carrier is converted to a reverse position;

FIG. 4 is a schematic side view of the carrier of FIG. 3;

FIG. 5 is an exploded view of the carrier of FIG. 1;

FIG. 6 is a schematic view of a carrier of the carrier of FIG. 1;

FIG. 7 is a second schematic structural view of the carrying device in the carrier of FIG. 1;

FIG. 8 is a schematic perspective view of a folding process of the carrier of FIG. 1;

FIG. 9 is a schematic side elevational view of FIG. 8;

FIG. 10 is a schematic perspective view of the folding carrier of FIG. 8;

FIG. 11 is a schematic side elevational view of FIG. 10;

FIG. 12 is a schematic perspective view of another folding manner of the carrier of FIG. 1;

FIG. 13 is a schematic side elevational view of FIG. 12;

FIG. 14 is a schematic perspective view of the carrier of FIG. 12 in a folded configuration;

FIG. 15 is a schematic side elevational view of FIG. 14;

Wherein, 100 parts of the bottom supporting mechanism, 200 parts of the bearing device, 201 parts of the unlocking piece;

1. a first bracket; 11, a first strut 12, a first cross bar;

2. The first support, the first strut, the second cross bar and the second cross bar;

3. The device comprises a push rod frame, 31, a lower push rod, 311, a rod body, 312, a connecting rod, 32, an upper push rod, 33, a push rod unlocking piece, 34 and a push rod locking joint;

4. A mounting base;

5. The seat comprises a supporting seat, a supporting seat rotating shaft, 6 parts, a seat, 61 parts, an avoidance groove, 62 parts, a seat rotating shaft, 6A parts, a first end part, 6B parts, a second end part, 7 parts, a backrest, 8 parts, a bracket, 9 parts and an armrest frame;

10. The wheel comprises a first wheel assembly, a second wheel assembly, an X0 rotation center line, an X1 first center line, an X2 second center line, an X3 third center line.

Detailed Description

The technical solutions of the embodiments of the present utility model will be clearly and completely described below with reference to the accompanying drawings so that the advantages and features of the present utility model will be more easily understood by those skilled in the art. It should be apparent that the described embodiments of the utility model are only some, but not all, embodiments of the utility model. All other embodiments, based on the embodiments of the utility model, which a person skilled in the art would obtain without making any inventive effort, are within the scope of the utility model.

The following description of the directions, such as up, down, left, right, front, and rear, is defined with reference to the directions observed when the vehicle is seated on the carrier with the occupant facing the traveling direction in the deployed state, and is only for the purpose of clearly explaining the relative positional relationship of the respective members on the vehicle.

Referring to fig. 1 to 15, a carrier having an unfolded state and a folded state includes a bottom support mechanism 100 and a carrying device 200, the bottom support mechanism 100 includes a mounting seat 4 extending in a left-right direction and a supporting seat 5 disposed on the mounting seat 4, the carrying device 200 includes a seat 6, the seat 6 is rotatably connected to the supporting seat 5 about a seat rotating shaft 62, the seat rotating shaft 62 extends in the left-right direction, and the seat rotating shaft 62 is disposed at a position near one end of the supporting seat 5 in a front-rear direction. When the carrier is folded, the seat 6 is folded toward the bottom support mechanism 100 by turning around the seat rotation shaft 62, so that the carrying device 200 is folded at the front side or the rear side of the bottom support mechanism 100.

In the carrier, the supporting seat 5 is rotatably mounted on the mounting seat 4 around the supporting seat rotating shaft 51, the supporting seat rotating shaft 51 extends in the vertical direction, and the bearing device 200 and the supporting seat 5 can rotate around the supporting seat rotating shaft 51 together to change the orientation of the seat 6. In this embodiment, as shown in fig. 5, the supporting seat rotating shaft 51 extends downward from the bottom of the supporting seat 5, the mounting seat 4 has a mounting hole into which the supporting seat rotating shaft 51 is fittingly inserted, and the axis of the supporting seat rotating shaft 51 forms a first center line X1.

In this carrier, the seat 6 extends in a substantially horizontal direction, and has a first end portion 6A and a second end portion 6B provided at opposite ends in a longitudinal direction thereof, the first end portion 6A is rotatably connected to one end portion of the support base 5 by a seat rotation shaft 51, and an axis line of the seat rotation shaft 51 is a second axis line X2. The second center line X2 extends in the left-right direction when the carrying device 200 is fixed to the bottom supporting mechanism 100 for carrying a child. The second end 6B is detachably provided with the support seat 5.

In the unfolded state, the second end 6B of the seat 6 is supported on the supporting seat 5 and fixed relative to the supporting seat 5, and the bearing device 200 and the supporting seat 5 rotate together around the first center line X1, so that the orientation of the seat 6 is changed, the bearing device 200 is in the forward position as shown in fig. 1 and 2, and the bearing device 200 is in the reverse position as shown in fig. 3 and 4.

When the carrier is folded, the second end 6B of the seat 6 can be separated from the supporting seat 5, and the seat 6 can rotate around the second center line X2 relative to the supporting seat 5, so that the seat 6 is converted to extend in the up-down direction and fold with the bottom supporting mechanism 100 in the front-back direction, so that the carrying device 200 can fold with the bottom supporting mechanism 100 to reduce the overall height of the folded carrier.

The carrier further includes a locking structure (not shown in the drawings) for locking the seat 6 to the support base 5, the locking structure being provided at a position of the support base 5 near the other end portion in the front-rear direction. The locking structure specifically comprises a locking groove and a locking piece matched with the locking groove, wherein the locking groove is arranged on one of the seat 6 and the supporting seat 5, and the locking piece is movably arranged on the other of the seat 6 and the supporting seat 5. In this embodiment, the locking member is movably disposed on the second end portion 6B, the locking groove is disposed on the supporting seat 5, the locking member, when being matched with the locking groove, makes the second end portion 6B fixed relative to the supporting seat 5, and when the locking member is disengaged from the locking groove, the seat 6 can be driven to rotate around the second center line X2 relative to the supporting seat 5 so as to separate the second end portion 6B from the supporting seat 5. Specifically, the locking member may be rotatably or movably disposed on the second end portion 6B, and may disengage from the locking groove or cooperate with the locking groove when moving relative to the second end portion 6B, so as to correspondingly unlock and lock the locking structure.

Referring to the drawings, in the present embodiment, the bottom support mechanism 100 is configured to be foldable, and includes a first bracket 1 and a second bracket 2, wherein an upper portion of the first bracket 1 and an upper portion of the second bracket 2 are rotatably connected about a rotation center line X0, the rotation center line X0 extends in a left-right direction, and a mounting seat 4 is fixedly provided at the upper portion of the first bracket 1. When the carrier is folded, the first bracket 1 and the second bracket 2 rotate around the rotation center line X0 to be mutually folded along the front and back directions, and the seat 6 rotates around the second center line X2 relative to the supporting seat 5 to be folded with the first bracket 1 or the second bracket 2.

When the rotation center line X0 and the second center line X2 are parallel to each other, the second center line X2 and the rotation center line X0 are disposed at a distance in the front-rear direction. The first central line X1 is located between the first end portion 6A and the second end portion 6B, and the rotation central line X0 is disposed coplanar with and perpendicular to the first central line X1. The center of gravity of the seat 6 on the bottom support mechanism 100 is substantially unchanged when the carrying device 200 is in the forward position and the reverse position, the overall shape of the vehicle is also substantially unchanged after the change, and when the carrying device 200 is folded, the folding shape of the vehicle is substantially identical when the seat 6 and other components on the carrying device 200 are folded with the first bracket 1 or the second bracket 2.

Referring to the drawings, in this embodiment, the carrying device 200 further includes a backrest 7, a bracket 8 and a handrail frame 9, wherein the lower portion of the backrest 7, one end portion of the seat 6 and one end portion of the handrail frame 9 are rotatably connected, and the upper portion of the bracket 8 is rotatably connected with the other end portion of the seat 6, wherein the handrail frame 9 is a U-shaped frame with an opening facing backward, the bracket 8 mainly provides two feet support for a rider, and the upper surface of the seat 6 gradually and downwardly extends from the side of the bracket 8 to the side of the backrest 7.

When the carrying device 200 is folded, the backrest 7 is folded relative to the seat 6, so that the armrest frame 9 is folded between the backrest 7 and the seat 6, the bracket 8 is rotated relative to the seat 6 and extends along the same length direction as the seat 6, so that the backrest 7 and the bracket are overlapped as much as possible in the length direction, and in this embodiment, the total length of the folded carrying device 200 is approximately the same as the length of the backrest 7.

In this embodiment, the carrier is in a folded state, the backrest 7 is folded at one side of the seat 6, and the bottom supporting mechanism 100 is folded at the other side of the seat 6, so that the folded carrier 200 can be folded at one side of the bottom supporting mechanism 100, and the back side of the backrest 7 is positioned at the outermost side of the folded carrier, so that the appearance of the carrier is smoother and easy to store, and some irregular components of the carrier 200 can be folded between the backrest 7 and the bottom supporting mechanism 100, thereby saving the occupied space and improving the overall aesthetic and regularity of the folded carrier.

In this embodiment, the second end 6B of the seat 6 is further movably provided with an unlocking member 201, and the unlocking member 201 is connected with the locking member to drive the locking member to move out of engagement with the locking slot, so as to unlock the locking structure. When the carrying device 200 is provided, a seat locking mechanism for locking the lower part of the backrest 7, the second end 6B of the seat 6 and one end of the armrest frame 9 relative to each other is provided, and the unlocking piece 201 may be configured to be used for unlocking the seat locking mechanism at the same time. In other embodiments, the unlocking member 201 may be provided at other positions on the carrying device 200.

Referring to the drawings, in this embodiment, the vehicle is a cart, the bottom support mechanism 100 further includes a first wheel assembly 10 and a second wheel assembly 20, specifically, the first wheel assembly 10 is disposed at the bottom of the first bracket 1, and the second wheel assembly 20 is disposed at the bottom of the second bracket 2.

Here, referring to fig. 5, the first bracket 1 includes two first struts 11 which are respectively provided at left and right sides and extend in the up and down direction, a first rail 12 which is fixedly provided between upper portions of the two first struts 11, and the mount 4 is fixedly provided at a middle position of the first rail 12, or the first rail 12 and the mount 4 are integrally provided so as to jointly constitute a lateral mount which extends in the left and right direction, a first wheel assembly 10 is provided at a lower portion of each group of the first struts 11, the first wheel assembly 10 being specifically a universal wheel assembly which is provided at a front side in the pushing direction, a second bracket 2 includes two second struts 21 which are respectively provided at left and right sides and extend in the up and down direction, and a second rail 22 which is fixedly provided between lower portions of the two second struts 21, and a group of second wheel assemblies 20 is provided at a lower portion of each second strut 21, the second wheel assemblies 20 being directional wheel assemblies which are provided at a rear side in the pushing direction.

The carrier further comprises a push rod frame 3, and the lower part of the push rod frame 3 is rotatably connected to the supporting seat 5, so that the carrying device 200, the supporting seat 5 and the push rod frame 3 can rotate together around the first central line X1 relative to the mounting seat 4 to realize the reversing of the seat 6. Specifically, the lower portion of the putter carrier 3 is rotatably connected to the support base 5 about a third center line X3, the third center line X3 and the second center line X2 being parallel to each other.

In the state shown in fig. 1 and 2, the carrying device 200 is in a forward position, the first end 6A of the seat 6 is forward and the second end 6B is rearward, the child sitting on the carrying device 200 faces forward, facing away from the pusher, and in the state shown in fig. 3 and 4, the carrying device 200 is in a reverse position, the first end 6A of the seat 6 is rearward and the second end 6B is forward, the child sitting on the carrying device 200 faces rearward, facing toward the pusher.

During the reversing operation, the operator can first drive the push rod frame 3 to rotate the push rod frame 3 and the bearing device 200 relative to the mounting seat 4 around the first central line X1, then drive the push rod frame 3 to turn back and forth relative to the supporting seat 5 around the third central line X3 after the orientation of the seat 6 is switched, so that the push rod frame 3 is switched, and the pushing end at the upper part of the push rod frame is switched to the same side as the second wheel assembly 20, namely, is positioned at the rear side of the carrier, so that the first wheel assembly 10 is kept in front of the traveling direction of the cart.

Referring to fig. 5, in the present embodiment, the push rod frame 3 includes a lower push rod 31 and an upper push rod 32, the lower push rod 31 has two push rods disposed on the left and right sides, the upper push rod 32 is a U-shaped rod, two ends of the upper push rod 32 are rotatably connected with the upper ends of the lower push rods 31 on both sides, a push rod locking joint 34 capable of locking the two push rods with each other is disposed at the rotational connection position of the upper push rod 32, a push rod unlocking member 33 is disposed in the middle of the upper push rod 32 for unlocking the push rod locking joint 34, the lower push rod 31 includes a rod body 311 and a connecting rod 312, the connecting rod 312 is bent inwards from the lower end of the rod body 311 to extend, the push rod frame 3 is rotatably connected with the support seat 5 through the connecting rods 312 on both sides, and the axis of the connecting rod 312 forms a third center line X3. The seat 6 is further provided with a avoidance groove 61 on both sides thereof, respectively, and the connection lever 312 is rotatably inserted into the avoidance groove 61. A push rod locking member (not shown) for locking the lower part of the push rod frame 3 and the supporting seat 5 to each other is also provided at the rotational connection position, and when the push rod locking member is specifically provided, the push rod locking member is unlocked by operating the push rod unlocking member 33.

When the carrier provided in this embodiment is folded, the pusher bar 3 can turn around the third center line X3 to the front side of the bottom supporting mechanism 100 or turn to the rear side of the bottom supporting mechanism 100 to fold with the bottom supporting mechanism 100. In the folded state, the putter frame 3 is folded to one side of the bottom support mechanism 100 or folded into the bottom support mechanism 100.

Specifically, referring to fig. 8 to 11, the carrier may be folded by folding the carrier 200 first, such that the backrest 7 is folded by rotating it with respect to the seat 6 and the bracket 9 is folded by rotating it with respect to the backrest 7, folding the upper push rod 32 by rotating it with respect to the lower push rod 31, such that the push rod frame 3 is turned backward, and such that the first and second brackets 1 and 2 are folded in the front-rear direction, such that the push rod frame 3 and the rod member in the bottom support mechanism 100 are folded in the front-rear direction, and driving the main body portion of the carrier 200 to rotate about the second center line X2 with respect to the support seat 5, such that the carrier is folded, such that the carrier in the folded state is as shown in fig. 11, wherein the push rod frame 3 and the first and second brackets 1 and 2 are folded with each other, and the carrier 200 is folded on one side of the bottom support mechanism 100.

Referring to fig. 12 to 15, the carrier may be folded by folding the carrier 200, such that the backrest 7 is folded by rotating it with respect to the seat 6 and the bracket 9 is folded by rotating it with respect to the backrest 7, folding the upper push rod 32 by rotating it with respect to the lower push rod 31, such that the push rod frame 3 is turned forward and the first and second brackets 1 and 2 are folded in the front-rear direction, such that the push rod frame 3 and the rod member in the bottom support mechanism 100 are folded in the front-rear direction, and driving the main body portion of the carrier 200 to rotate about the second center line X2 with respect to the support seat 5, such that the carrier is folded, wherein the push rod frame 3 and the first and second brackets 1 and 2 are folded with each other, and the carrier 200 is folded at one side of the bottom support mechanism 100, as shown in fig. 14.

When the folding device is specifically arranged, the locking mechanism for locking the first bracket 1 and the second bracket 2 is arranged on the bottom supporting mechanism 100, and the locking mechanism is configured to unlock when the rear part of the supporting seat 5 is lifted, so that when the folding device is folded, after the push rod frame 3 is turned backwards or forwards relative to the supporting seat 5, the rear part of the supporting seat 5 is lifted upwards, the bottom supporting mechanism 100 can be folded, and the main body part of the bearing device 200 is turned towards one side of the bottom supporting mechanism 100, so that the folding operation is more convenient.

In summary, in the carrier provided by the embodiment of the utility model, the bearing device 200 can rotate relative to the bottom supporting mechanism 100 to change the orientation of the seat 6, and meanwhile, the seat 6 can rotate relative to the supporting seat 5 to fold together with the bottom supporting mechanism 100 along the front-rear direction, so that the bearing device 200 does not need to be disassembled and folded separately for storage, the problem that the bearing device 200 is too large to store due to folding together with the bottom supporting mechanism 100 is avoided, and convenience is brought to daily use of users.

The above embodiments are only for illustrating the technical concept and features of the present utility model, and are intended to enable those skilled in the art to understand the content of the present utility model and to implement the same, but are not intended to limit the scope of the present utility model, and all equivalent changes or modifications made according to the spirit of the present utility model should be included in the scope of the present utility model.

Claims

1. A vehicle having an unfolded state and a folded state, characterized in that the vehicle comprises:

The bottom support mechanism includes a mounting base extending in a left-right direction and a support base disposed on the mounting base;

A support device, the support device including a seat, the seat being rotatably connected to a support about a seat pivot, the seat pivot extending in the left-right direction and being located at one end of the support near the front-rear direction;

When the vehicle is folded, the seat rotates around the seat pivot and folds towards the bottom support mechanism.

2. The carrier according to claim 1, characterized in that: the support base is rotatably mounted on the mounting base about a support base pivot, and the support base pivot extends in a vertical direction.

3. The vehicle according to claim 1, wherein the vehicle further comprises a locking structure for locking the seat to the support base, the locking structure being disposed at a position near the other end of the support base in the front-rear direction.

4. The vehicle according to claim 3, characterized in that: the locking structure includes a locking groove and a locking member cooperating with the locking groove, the locking groove being disposed on one of the seat and the support seat, and the locking member being movably disposed on the other of the seat and the support seat.

5. The vehicle according to claim 4, characterized in that: the seat has a first end and a second end disposed at opposite ends in its own length direction, the first end is rotatably connected to one end of the support seat about the seat pivot axis, the second end is detachably disposed from the support seat, and the locking structure is disposed between the second end and the other end of the support seat.

6. The vehicle according to claim 5, characterized in that: the locking member is movably disposed on the second end, the locking groove is disposed on the support base, and an unlocking member is movably disposed on the second end, the unlocking member being connected to the locking member so as to drive the locking member to move and disengage from the locking groove.

7. The vehicle according to claim 1, characterized in that: the bottom support mechanism includes a first bracket and a second bracket, the upper part of the first bracket and the upper part of the second bracket are rotatably connected, the mounting seat is fixedly disposed on the upper part of the first bracket, the vehicle is in a folded state, the first bracket and the second bracket are retracted together, and the seat is close to the first bracket or the second bracket.

8. The vehicle according to claim 1, characterized in that: the carrying device further includes a backrest, the backrest being rotatably connected to the seat, the vehicle being in a folded state, the backrest being folded to one side of the seat, and the bottom support mechanism being folded to the other side of the seat.

9. The vehicle according to claim 1, characterized in that: the vehicle further includes a push rod frame, the lower part of which is rotatably connected to the support base, and when the vehicle is folded, the push rod frame flips forward or backward to retract with the bottom support mechanism.

10. The vehicle according to claim 9, characterized in that: the vehicle is a trolley, the bottom support mechanism includes a first bracket and a second bracket, the upper part of the first bracket is rotatably connected to the upper part of the second bracket, the lower part of the first bracket is provided with a first wheel assembly, and the lower part of the second bracket is provided with a second wheel assembly; the mounting seat is fixedly disposed on the upper part of the first bracket.