Shopping cart with subwheels

Abstract

We provide shopping carts that can easily cross the comb plates of moving walkways. [Solution] The system includes a frame 110, front wheels 120 having protrusions formed on their outer circumference that can be inserted into rail grooves on the upper surface of the moving walk, and positioned on both sides of the lower end of the front end of the frame, a braking unit 140 that restricts the rolling motion of the front wheels when the protrusions of the front wheels are inserted into rail grooves on the upper surface of the moving walk, and sub-wheels positioned to protrude relatively forward compared to the front wheels for contact with the comb plate of the moving walk, wherein the lower end of the sub-wheels is separated upward from the floor surface that supports the lower end of the front wheels, and the separation distance between the lower end of the sub-wheels and the floor surface is set to be less than or equal to the thickness of the comb plate M2.

Description

Technical Field

[0001] The present invention relates to a shopping cart provided with a sub-wheel. More specifically, the present invention relates to a shopping cart provided with a sub-wheel that can easily cross the comb plate of a moving walk by means of the sub-wheel while preventing the sub-wheel from rolling on the upper surface of the moving walk, and can be used more safely and conveniently.

Background Art

[0002] Generally, in large discount stores, shopping malls, airports, etc., various forms and types of carts (hereinafter generally referred to as "shopping carts") used for purchasing goods, carrying children, or carrying luggage are used.

[0003] The conventional shopping cart is mainly used for transporting goods that a customer intends to purchase or has purchased when shopping, or has a function of carrying a child while shopping. The above-mentioned shopping cart has various structures depending on the environment in which it is used. Generally, as shown in FIG. 1, a handle 12 is provided on the upper part of a frame 10 constituting the main body, a moving tire 11 is mounted on the lower part of the frame 10, and a basket 13 for loading goods and articles is installed in the central part of the frame 10.

[0004] Particularly, on flat ground, it acts as a rolling means, and on a moving sidewalk (hereinafter abbreviated as "moving walk"), a tire for a shopping cart having a tire edge inserted into a rail groove formed on the mounting surface has been used.

[0005] Referring to Figure 2, the tire 20 used in a conventional shopping cart comprises a wheel 21, a fork member 22 mounted on the top of the wheel 21, a pair of rotating guide plates 25 mounted on both sides of the wheel 21, a brake 23 fixedly attached to a part of the outer surface of the fork member 22, and a brake member 24 detachably attached to the bottom of the brake 23. The brake 23, the fork member 22, and the rotating guide plates 25 are fixedly attached to the wheel 21 in this order by bolts 26 and nuts (not shown).

[0006] At the end of the moving walkway, a comb plate of a predetermined height is placed to prevent shopping carts from being pushed out too quickly.

[0007] However, with conventional shopping carts, when loaded with many items and placed on a moving walkway, the front wheels engage with the comb plate while the braking force of the braking element is not released. At this point, unless the user pushes the shopping cart forward, the front wheels will engage with the comb plate and stop, creating a problem of collision with other shopping carts following behind.

[0008] In recent large supermarkets, to prevent such accidents, assistants are stationed at the end of the moving walkways to pull shopping carts. However, repeatedly pulling shopping carts for extended periods increases the risk of musculoskeletal disorders, so there is a need to develop technologies that allow for safer and more convenient use on moving walkways. [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] Korean Registered Utility Model No. 20-0255997 [Overview of the project] [Problems that the invention aims to solve]

[0010] Therefore, an object of the present invention is to provide a shopping cart equipped with sub-wheels that allow the front wheels to easily cross the comb plate of a moving walkway, in order to solve the problems of the conventional invention.

[0011] Furthermore, the objective is to provide a shopping cart equipped with sub-wheels that can be used more safely and conveniently by preventing the sub-wheels from rolling on the moving walkway even when the lower end of the sub-wheel changes to a position relatively lower than the lower end of the brake part due to wear of the brake part that restricts the movement of the shopping cart on the moving walkway or deformation of the frame.

[0012] Furthermore, the aim is to provide a shopping cart equipped with sub-wheels that can be easily installed on existing shopping carts. [Means for solving the problem]

[0013] The aforementioned objective is achieved by a shopping cart equipped with sub-wheels, comprising: a frame; front wheels positioned on both sides of the lower end of the front end of the frame, each having a projection formed on its outer circumference that can be inserted into a rail groove on the upper surface of the moving walk; braking units that restrict the rolling motion of the front wheels when the projections of the front wheels are inserted into the rail groove on the upper surface of the moving walk; and sub-wheels positioned to protrude relatively forward compared to the front wheels for contact with the comb plate of the moving walk, wherein the lower end of the sub-wheels is separated upward from the floor surface that supports the lower end of the front wheels, and the separation distance between the lower end of the sub-wheels and the floor surface is set to be less than or equal to the thickness of the comb plate.

[0014] Here, it is preferable that the lower end of the sub-wheel is positioned relatively higher than the lower end of the braking unit, and that the distance between the lower end of the sub-wheel and the lower end of the braking unit is set to be less than or equal to the distance between the upper surface of the moving walk and the upper surface of the comb plate.

[0015] Furthermore, it is preferable that a flange portion is formed radially protruding from the outer circumferential surface of the sub-wheel, which can be inserted into the rail groove on the upper surface of the moving walk.

[0016] Furthermore, it is preferable that a number of flange portions are provided and that they be spaced apart from each other in accordance with the spacing of the rail grooves formed on the upper surface of the moving walk.

[0017] Furthermore, it is preferable to further include a fixing bracket that includes a first plate detachably assembled to a horizontal bar located at the lower end of the front end of the frame while supporting the sub-wheel so as to be rotatable on an axis, and a second plate extending from the rear end of the first plate and supporting the lower tray located at the bottom of the frame so as to be rotatable up and down.

[0018] Furthermore, it is preferable that the horizontal bar has a first connecting portion which can be connected to the second connecting portion of the lower tray, the first plate has a third connecting portion which can be connected to the first connecting portion of the horizontal bar, and the second plate has a fourth connecting portion which can be connected to the second connecting portion of the lower tray that has been separated from the first connecting portion of the horizontal bar.

[0019] Furthermore, it is preferable that the upper surface of the second plate is set to have a height corresponding to the upper surface of the horizontal bar when the first plate is connected to the horizontal bar. [Effects of the Invention]

[0020] According to the present invention, a shopping cart is provided that has sub-wheels that allow the front wheels to easily cross the comb plate of a moving walkway.

[0021] Also, even when the lower end of the sub-wheel changes to a position relatively lower than the lower end of the braking part due to wear of the braking part that restricts the movement of the shopping cart on the moving walkway or deformation of the frame, etc., the sub-wheel is prevented from rolling on the moving walkway, thereby providing a shopping cart equipped with a sub-wheel that can be used more safely and conveniently.

[0022] Also, there is provided a shopping cart equipped with a sub-wheel that can be easily installed on an existing shopping cart that is already in use.

Brief Description of the Drawings

[0023] [Figure 1] It is a perspective view of a conventional tire for a shopping cart. [Figure 2] It is a perspective view for explaining the operation of the tire for a shopping cart in FIG. 1. [Figure 3] It is a perspective view of a shopping cart equipped with the sub-wheel of the present invention. [Figure 4] It is an exploded perspective view of a shopping cart equipped with the sub-wheel of the present invention. [Figure 5] It is a side sectional view of a shopping cart equipped with the sub-wheel of the present invention. [Figure 6] It is a front configuration diagram of FIG. 5. [Figure 7] It is a view showing a state where a shopping cart equipped with the sub-wheel of the present invention is located on a moving walkway. [Figure 8] It is a view showing a state where the lower end of the sub-wheel is arranged at the same height as the lower end of the braking part or at a position relatively lower than the lower end of the braking part due to wear of the braking part from the state of FIG. 7. [Figure 9] It is a view showing a process in which the sub-wheel and the front wheel of a shopping cart equipped with the sub-wheel of the present invention cross over a comb plate. [Figure 10]This figure shows the process of installing the sub-wheel and fixing bracket of the shopping cart equipped with the sub-wheel of the present invention onto an existing shopping cart. [Modes for carrying out the invention]

[0024] Before proceeding, we will use the same reference numerals to describe components that have the same configuration in many embodiments, and will describe them representatively in the first embodiment. In other embodiments, we will describe configurations that differ from those in the first embodiment.

[0025] A shopping cart equipped with sub-wheels according to the first embodiment of the present invention will be described in detail below with reference to the attached drawings.

[0026] Of the attached drawings, Figure 3 is a perspective view of a shopping cart equipped with the sub-wheels of the present invention, Figure 4 is an exploded perspective view of a shopping cart equipped with the sub-wheels of the present invention, Figure 5 is a side cross-sectional view of a shopping cart equipped with the sub-wheels of the present invention, and Figure 6 is a front view of Figure 5.

[0027] As shown in the drawings, the shopping cart with sub-wheels according to the present invention includes a frame 110, a front wheel 120, a rear wheel 130, a braking unit 140, a lower tray 150, a sub-wheel 160, and a fixing bracket 170.

[0028] The frame 110 includes a horizontal bar 111 positioned horizontally at the lower end of the front end, and consists of a basic skeletal structure that can connect a basket for storing shopping items and a handle.

[0029] The front wheels 120 are positioned at the lower ends on both sides of the front end of the frame 110, and numerous protrusions 121 are formed on their outer circumferential surfaces, which can be inserted into the rail grooves M1 on the upper surface of the moving walk M. The rear wheel 130 has the same configuration as the front wheel 120 and is positioned at the lower ends on both sides of the rear end of the frame 110.

[0030] The braking unit 140 is configured to restrict the rolling motion of the front wheel 120 when the protruding portion 121 of the front wheel 120 is inserted into the rail groove M1 on the upper surface of the moving walk M. For example, the braking unit 140 may be in the form of a friction member that can be closely supported on the upper surface of the moving walk M, as in Korean Utility Model No. 20-0255997, when the protruding portion 121 of the front wheel 120 is inserted into the rail groove M1 of the moving walk M.

[0031] The lower tray 150 is positioned at the lower end of the frame 110 to load shopping items into the bottom of the basket.

[0032] The lower tray 150 can be connected at its front end to the horizontal bar 111 of the frame 110 so as to be vertically rotatable, allowing multiple shopping carts to be stacked front to back for storage. For this purpose, a first connecting portion 111a is formed on the horizontal bar 111 of the tray, and a second connecting portion 151 is formed at the front end of the lower tray 150 so as to be vertically rotatable to the first connecting portion 111a. For example, the first connecting portion 111a may consist of a pair of through holes spaced apart to the left and right, and the second connecting portion 151 may have a hook shape bent downward at a 90-degree angle so as to be inserted into each of the through holes at positions corresponding to the pair of through holes.

[0033] On the other hand, the rear end of the lower tray 150 can be provided with a stopper that is supported by the frame 110 in a relatively horizontal downward rotation position, thereby limiting further downward rotation. This allows the lower tray 150 to load items while maintaining a horizontal position under normal circumstances, and to rotate upward when a shopping cart is placed behind it.

[0034] The frame 110, front wheel 120, rear wheel 130, braking unit 140, and lower tray 150 described above are all known technologies widely used in general shopping carts, so a detailed explanation of them will be omitted.

[0035] The sub-wheel 160 is positioned to protrude relatively forward compared to the front wheel 120, so that it can contact the comb plate M2 of the moving walk M before the front wheel 120 contacts the comb plate M2.

[0036] Furthermore, the lower end of the sub-wheel 160 can be positioned upward from the floor surface supporting the lower end of the front wheel 120, preferably positioned relatively above the lower end of the braking section 140. In this case, if the distance between the lower end of the sub-wheel 160 and the lower end of the braking section 140 exceeds the thickness of the comb plate M2, the sub-wheel 160 will not be able to contact the comb plate M2. Therefore, it is preferable that the distance between the lower end of the sub-wheel 160 and the lower end of the braking section 140 be set to be less than or equal to the thickness of the comb plate M2. Here, the lower end of the braking section 140 refers to the position that contacts the upper surface of the moving walk M when the braking section 140 is made of a friction member, and the thickness of the comb plate M2 refers to the distance between the upper surface of the moving walk and the upper surface of the comb plate.

[0037] The sub-wheel 160 includes a flange portion 161 that can be inserted into a rail groove M1 on the upper surface of the moving walk M. Such flange portions 161 may be configured to extend radially from the outer circumferential surface of the sub-wheel 160, and a number of them may be provided and spaced apart from each other along the axial direction of the sub-wheel 160. The spacing between the multiple flange portions 161 may be set to correspond to the spacing of the rail grooves M1 of the moving walk M. For example, flange portions 161 may be formed at both ends of the sub-wheel 160, and the spacing may be set to correspond to the pitch of 2 to 5 rail grooves M1.

[0038] On the other hand, in this embodiment, the lower end of the subwheel 160 can be understood as the lower end of the outermost outer surface of the subwheel 160, that is, the lower end of the flange portion 161.

[0039] The fixing bracket 170 includes a first plate 171 assembled to the lower part of a horizontal bar 111 positioned at the lower end of the front end of the frame 110, a support bar 172 positioned at a downward inclination toward the front from the lower part of the frame 110 and supporting the sub-wheel 160 so that it can rotate on an axis, and a second plate 173 extending from the rear end of the first plate 171 and capable of supporting the lower tray so that it can rotate up and down.

[0040] The first plate 171 has a third connecting portion 171a that can be connected to the first connecting portion 111a of the horizontal bar 111, and the second plate 173 has a fourth connecting portion 173a that can be connected to the second connecting portion 151 of the lower tray.

[0041] For example, the third joint 171a consists of a pair of through holes that can communicate with the pair of through holes that constitute the first joint 111a, and the first joint 111a and the third joint 171a can be detachably fastened together by fastening members B such as bolts and nuts.

[0042] Furthermore, the fourth connecting portion 173a may consist of a pair of through holes spaced apart to the left and right at the same interval as the first connecting portion 111a for connection with the second connecting portion 151. Therefore, the second connecting portion 151 of the lower tray 150, which is a hook shape bent downward at a 90-degree angle, can be connected to the fourth connecting portion 173a instead of the first connecting portion 111a of the horizontal bar 111.

[0043] The second plate 173, which extends from the rear end of the first plate 171, is positioned above the top surface of the first plate 171 by the thickness of the horizontal bar 111. As a result, when the first plate 171 is in close contact with the bottom surface of the horizontal bar 111, the top surface of the second plate 173 is at the same height as the top surface of the horizontal bar 111. Therefore, connecting the lower tray 150 to the second plate 173 prevents the horizontal slope of the lower tray 150 from changing.

[0044] Furthermore, although this embodiment has described an example in which the first plate 171 is positioned below the horizontal bar 111 and connected to it, it is also possible for the first plate 171 to be positioned above the horizontal bar 111. In this case, the second plate 173 must be positioned below the upper surface of the first plate 171 by the thickness of the horizontal bar 111.

[0045] From here, we will describe the operation of the first embodiment of the shopping cart equipped with the sub-wheels mentioned above.

[0046] Of the attached drawings, Figure 7 shows a shopping cart equipped with the sub-wheels of the present invention positioned on a moving walkway, and Figure 8 shows a state in which, due to wear of the braking part, the lower end of the sub-wheel is positioned at the same height as the lower end of the braking part or relatively lower than the lower end of the braking part, compared to the state in Figure 7.

[0047] First, the function of the flange portion 161 of the sub-wheel 160 will be explained using Figures 7 and 8.

[0048] Figure 7(a) shows the side view of the front wheel 120 and sub-wheel 160, and Figure 7(b) shows the front view of the front wheel 120 and sub-wheel 160.

[0049] As shown in Figure 7, the sub-wheel 160 is set so that its lower end is positioned relatively higher than the lower end of the braking unit 140, and the distance between the lower end of the sub-wheel 160 and the lower end of the braking unit 140 is set to be less than or equal to the thickness of the comb plate M2.

[0050] Therefore, the protruding portion 121 of the front wheel 120 can be inserted into the rail groove M1 formed on the upper surface of the moving walk M, and the braking portion 140 can be in close contact with the upper surface of the moving walk M and exert braking force, while the sub-wheel 160 can be separated from the upper surface of the moving walk M.

[0051] However, since the braking portion 140 is made of a friction material such as rubber, it can easily wear down due to friction with the moving walk M. In other words, the lower end surface of the braking portion 140 will gradually move upward during the process of using the shopping cart.

[0052] As shown in Figure 8, as the lower end surface of the braking portion 140 rises due to wear, the projection 121 formed on the outer circumference of the front wheel 120 is gradually inserted deeper into the rail groove M1 of the moving walk M, and the lower end of the sub-wheel 160 may move to a position relatively lower than the lower end of the braking portion 140.

[0053] When the outer surface of the sub-wheel 160 is supported by the upper surface of the moving walk M due to wear of the braking part 140, the sub-wheel 160 rolls on the moving walk M while supporting the load of the shopping cart, instead of the braking part 140 which is in close contact with the upper surface of the moving walk M and restricts the movement of the front end of the shopping cart. This results in a loss of braking force at the front end of the shopping cart. In particular, when the sub-wheel 160 contacts the upper surface of the moving walk M on a downward-sloping moving walk M, a shopping cart loaded with heavy shopping items can move arbitrarily downward along the sloped surface, which increases the risk of accidents.

[0054] In this embodiment, a flange portion 161 is formed on the outer circumferential surface of the sub-wheel 160, which can be inserted into the rail groove on the upper surface of the moving walk M, protruding radially.

[0055] Therefore, even if the lower end of the sub-wheel 160 moves to a position relatively lower than the lower end of the braking part 140 due to wear of the braking part 140, the lower end of the sub-wheel 160, i.e., the lower end of the flange part 161, is inserted into the rail groove on the upper surface of the moving walk M and does not come into direct contact with the moving walk M. This not only prevents the sub-wheel 160 from rolling on the moving walk M, but also allows the braking part 140 to make stable contact with the upper surface of the moving walk M, thereby enabling it to exert a stable braking force.

[0056] Of the attached drawings, Figure 9 shows the process by which the sub-wheel and front wheel overcome the comb plate in a shopping cart equipped with the sub-wheel of the present invention.

[0057] Figure 9(a) shows the state in which the sub-wheel 160 is not in contact with the comb plate M2, (b) shows the state in which the sub-wheel 160 is raised above the comb plate M2, and (c) shows the state in which the front wheel 120 is raised above the comb plate M2.

[0058] As shown in Figure 9(a), the sub-wheel 160 in this embodiment is positioned to protrude relatively forward compared to the front wheel 120 so that it can contact the comb plate M2 of the moving walk M before the front wheel 120 contacts the comb plate M2.

[0059] The sub-wheel 160 is set so that its lower end is positioned relatively higher than the lower end of the braking unit 140. If the distance between the lower end of the sub-wheel 160 and the lower end of the braking unit 140 exceeds the thickness of the comb plate M2, the sub-wheel 160 will not come into contact with the comb plate M2 during the process of the shopping cart leaving the moving walkway M, and therefore will not be able to perform its function. For this reason, it is preferable that the distance between the lower end of the sub-wheel 160 and the lower end of the braking unit 140 be set to be less than or equal to the thickness of the comb plate M2.

[0060] When the front wheel 120 is positioned on the moving walkway M, the protruding portion 121 of the front wheel 120 is inserted into the rail groove M1 of the moving walkway M, causing the braking portion 140 to support the load of the shopping cart in close contact with the upper surface of the moving walkway M, thereby restricting the movement of the shopping cart on the moving walkway M.

[0061] In this configuration, the lower end of the sub-wheel 160 is positioned relatively higher than the lower end of the braking unit 140, and the distance between the lower end of the sub-wheel 160 and the lower end of the braking unit 140 is set to be less than or equal to the thickness of the comb plate M2. Therefore, when the braking unit 140 is in close contact with the upper surface of the moving walk M, the sub-wheel 160 is not in contact with the moving walk M.

[0062] Next, as shown in Figure 9(b), when the sub-wheel 160 comes into contact with the comb plate M2 located at the end of the moving walkway M during the process of the shopping cart moving along the moving walkway M, the sub-wheel 160 moves to the upper surface of the comb plate M2 while rolling along the inclined surface at the front end of the comb plate M2. At this time, since the sub-wheel 160 comes into contact with the inclined surface at the front end of the comb plate M2 at a position separated from the upper surface of the moving walkway M, the contact angle with the comb plate M2 can be minimized. This not only minimizes the impact generated when the sub-wheel 160 and the comb plate M2 collide, but also allows the sub-wheel 160 to easily rise to the upper surface of the comb plate M2 with little force.

[0063] The load at the front end of the shopping cart is supported by the sub-wheels 160 that roll along the upper surface of the comb plate M2, and the braking unit 140 moves upward together with the sub-wheels 160, separating from the moving walk M and losing braking force.

[0064] Next, as shown in Figure 9(c), the front wheel 120, which follows the sub-wheel 160 and contacts the comb plate M2, contacts the comb plate M2 when the braking force of the braking unit 140 is lost, thus minimizing the impact generated at the time of contact. Furthermore, by contacting the comb plate M2 while raised by the sub-wheel 160, the contact angle with the comb plate M2 is minimized, allowing the front wheel to easily rise to the upper surface of the comb plate M2 with little force.

[0065] Figure 10 of the attached drawings shows the process of installing the sub-wheels of the shopping cart equipped with the sub-wheels of the present invention onto an existing shopping cart.

[0066] Figure 10(a) shows an existing shopping cart with the lower tray 150 separated in order to install the sub-wheels 160, and Figure 10(b) shows a fixed bracket 170 to which the sub-wheels 160 are attached connected between the horizontal bar 111 and the lower tray 150.

[0067] Existing shopping carts have a connecting structure in which a hook-shaped second connecting part 151 provided at the front end of the lower tray 150 is inserted into a through-hole-shaped first connecting part 111a that penetrates perpendicularly through the horizontal bar 111 of the frame 110, as shown in Figure 10(a). Therefore, the second connecting part 151 of the lower tray 150 can be separated from the first connecting part 111a of the horizontal bar 111 by lifting it upward.

[0068] Next, as shown in Figure 10(b), the first plate 171 of the fixing bracket 170 is placed on the lower side surface of the horizontal bar 111, and then the fastening member B is inserted and fastened to the first joint portion 111a of the horizontal bar 111 and the third joint portion 171a of the first plate 171, thereby fixing the first plate 171 with the sub-wheel 160 attached to the lower part of the horizontal bar 111.

[0069] On the other hand, the second plate 173, which is provided at the rear end of the first plate 171, is provided with a fourth connecting portion 173a for connecting with the lower tray 150 that was separated earlier. The second plate 173 is positioned relatively higher than the first plate 171, and the difference in height between the top surface of the first plate 171 and the top surface of the second plate 173 is set to correspond to the thickness of the horizontal bar 111. Therefore, the top surface of the second plate 173 can be positioned at a height corresponding to the top surface of the horizontal bar 111, thus preventing a change in the support height of the lower tray 150.

[0070] If the height of the lower tray 150 changes during the process of moving the second connecting portion 151 of the lower tray 150 from the first connecting portion 111a of the horizontal bar 111 to the fourth connecting portion 173a of the second plate 173 and connecting them, this can act as an obstacle when stacking and storing multiple shopping carts. Therefore, it is preferable to maintain a constant installation height for the lower tray 150.

[0071] The scope of the present invention is not limited to the embodiments described above, but can be embodied in a variety of forms within the scope of the attached claims. Anyone with ordinary skill in the art to which the invention pertains will find the claims to be within a wide range of forms that can be modified without departing from the spirit of the invention as claimed in the claims. [Explanation of symbols]

[0072] 110: Frame, 111: Horizontal bar, 111a: First joint, 120: Front wheel, 121: Protrusion, 130: Rear wheel, 140: Braking section, 150: Lower tray, 151: Second coupling section, 160: Sub-wheel, 161: Flange section, 170: Fixing bracket, 171: First plate, 171a: Third joint, 172: Support bar, 173: Second plate, 173a: Fourth joint, B: Fastening member, M: Moving walkway, M1: Rail groove, M2: Comb plate

Claims

1. Frame (110); Front wheels (120) are positioned on both sides of the lower end of the front end of the frame (110), with protrusions (121) formed on their outer circumferential surface that can be inserted into rail grooves on the upper surface of the moving walk; A braking unit (140) that restricts the rolling motion of the front wheel when the protruding portion (121) of the front wheel is inserted into the rail groove on the upper surface of the moving walk; It includes a sub-wheel (160) positioned to protrude relatively forward compared to the front wheel (120) for contact with the comb plate of the moving walkway, A shopping cart equipped with a sub-wheel, characterized in that the lower end of the outer surface of the sub-wheel (160) is separated upward from the floor surface on which the lower end of the front wheel (120) is supported.

2. A shopping cart equipped with a sub-wheel according to claim 1, characterized in that the lower end of the outer circumferential surface of the sub-wheel (160) is positioned relatively higher than the lower end of the braking part (140), and the distance between the lower end of the outer circumferential surface of the sub-wheel (160) and the lower end of the braking part (140) is set to be less than or equal to the thickness of the comb plate.

3. A shopping cart equipped with a sub-wheel according to claim 2, characterized in that a flange portion (161) that can be inserted into a rail groove on the upper surface of the moving walk is formed to protrude radially from the outer circumferential surface of the sub-wheel (160).

4. A shopping cart equipped with sub-wheels according to claim 3, characterized in that a number of flange portions (161) are provided and are spaced apart from each other in accordance with the spacing of rail grooves formed on the upper surface of the moving walkway.

5. A shopping cart with a sub-wheel according to claim 1, further comprising a fixing bracket (170) including a first plate (171) which is detachably assembled to a horizontal bar located at the lower end of the front end of the frame, with the sub-wheel (160) being rotatably supported on an axis; and a second plate (173) which extends from the rear end of the first plate and supports a lower tray (150) located at the bottom of the frame so that it can rotate up and down; the shopping cart with a sub-wheel according to claim 1.

6. A shopping cart equipped with sub-wheels according to claim 5, characterized in that the horizontal bar (111) has a first connecting portion (111a) which can be connected to the second connecting portion (151) of the lower tray (150), the first plate (171) has a third connecting portion (171a) which can be connected to the first connecting portion (111a) of the horizontal bar, and the second plate (173) has a fourth connecting portion (173a) which can be connected to the second connecting portion (151) of the lower tray (150) which has been separated from the first connecting portion (111a) of the horizontal bar.

7. The shopping cart equipped with sub-wheels according to claim 5, characterized in that the upper surface of the second plate (173) is set to have a height corresponding to the upper surface of the horizontal bar when the first plate (171) is connected to the horizontal bar (111).

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