Auxiliary wheel device for heavy truck rescue
By designing a support frame, buffer pads, and auxiliary wheel device with locking components for heavy truck rescue, the problem of heavy trucks occupying the road for a long time due to malfunctions is solved, enabling rapid installation, safe and reliable rescue, applicable to various road conditions, and significantly improving road traffic safety.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- CHONGQING SIHANG TONGHE EXPRESSWAY INVESTMENT CO LTD
- Filing Date
- 2025-08-07
- Publication Date
- 2026-07-14
AI Technical Summary
Heavy trucks frequently block traffic due to malfunctions such as damaged rear axle differentials or locked rear wheels. Existing rescue methods require large equipment, take a long time to prepare, are prone to causing traffic congestion, and pose safety hazards. There is a lack of quick-installation, safe and reliable rescue devices.
Design an auxiliary wheel device including a support frame, buffer pads, and locking components. The support frame is equipped with a traveling wheel, the buffer pads are used to support the axle head of the faulty wheel, and the locking components are used for fixation. It can quickly replace the faulty wheel and is suitable for various road conditions.
It significantly reduces the time that accident vehicles occupy the road, improves road traffic safety, and the device can be installed quickly, is suitable for various road conditions, avoids secondary damage, and ensures operational safety.
Smart Images

Figure CN224491006U_ABST
Abstract
Description
Technical Field
[0001] This utility model belongs to the field of vehicle emergency rescue technology, specifically relating to an auxiliary wheel device for heavy truck rescue. Background Technology
[0002] Currently, prolonged road closures caused by heavy-duty trucks (any truck with a total mass exceeding 3500 kg) that cannot be directly towed, such as damaged rear axle differentials or locked rear wheels, are quite common. These disabled vehicles often require specialized rescue equipment to move, and traditional rescue methods have several limitations: First, heavy-duty truck breakdowns typically require large lifting equipment for relocation, which not only takes a long time to prepare but also causes severe traffic congestion; second, large rescue equipment is difficult to deploy in confined spaces such as tunnels and bridges; third, traditional towing methods can easily cause secondary damage when the vehicle's wheel system fails, increasing repair costs; most importantly, prolonged road closures pose serious safety hazards to rescue personnel, especially in high-traffic areas such as highways, easily leading to secondary traffic accidents. The current technology lacks a quick-installing, safe, reliable, and adaptable temporary moving device for heavy-duty trucks suitable for various road conditions, directly impacting road rescue efficiency and traffic safety.
[0003] Therefore, there is an urgent need to develop and design a device that can quickly replace a disabled wheel, assist in the towing and rescue of heavy trucks in such accidents, significantly reduce the time that accident vehicles occupy the road, and thus improve road traffic safety. Utility Model Content
[0004] In view of this, the purpose of this utility model is to provide an auxiliary wheel device for heavy truck rescue. This device has the advantages of being quick to install, safe and reliable, applicable to various road conditions, significantly reducing the time that accident vehicles occupy the road, and improving road traffic safety.
[0005] To achieve the above objectives, this utility model provides the following technical solution: an auxiliary wheel device for heavy truck rescue, comprising: a support frame, wherein the support frame is provided with a traveling wheel; a buffer pad, disposed on the support frame to provide a support point for the axle head at the faulty wheel when in use; and a locking member, used to fix the axle head at the faulty wheel to the buffer pad.
[0006] Furthermore, the support frame includes a longitudinal support beam and a first transverse support beam and a second transverse support beam respectively disposed at both ends of the longitudinal support beam; there are four wheels, which are disposed at both ends of the first transverse support beam and the second transverse support beam respectively; the buffer pad is placed on top of the longitudinal support beam.
[0007] Furthermore, the longitudinal support beam includes a longitudinal intermediate beam, and a first longitudinal sleeve beam and a second longitudinal sleeve beam that are slidably sleeved and locked at both ends of the longitudinal intermediate beam; the first transverse support beam is fixed to the top of the first longitudinal sleeve beam and can move with the first longitudinal sleeve beam, and the second transverse support beam is fixed to the second longitudinal sleeve beam and can move with the second longitudinal sleeve beam.
[0008] Furthermore, the support frame also includes a first oblique reinforcing plate and a second oblique reinforcing plate respectively disposed at both ends of the longitudinal support beam; the first oblique reinforcing plate forms a triangular reinforcing structure with the first longitudinal sleeve beam and the first transverse support beam; the second oblique reinforcing plate forms a triangular reinforcing structure with the second longitudinal sleeve beam and the second transverse support beam.
[0009] Furthermore, the longitudinal support beams are in two sets; limiting baffles are fixed on the outer sides of the two sets of longitudinal support beams in the lateral direction, and the buffer pad is located between the two limiting baffles.
[0010] Furthermore, locking lugs are fixedly provided on the first and second transverse support beams respectively, and locking holes are provided on the locking lugs; the locking element is a locking rope, and the locking rope is passed through the locking hole to complete the binding and installation of the axle head and the buffer pad at the faulty wheel.
[0011] Furthermore, the traveling wheel includes an axle and a traveling wheel body rotatably mounted on the axle; the axles of the four traveling wheels are detachably and fixedly connected to the two ends of the first transverse support beam and the second transverse support beam, respectively.
[0012] Furthermore, both the first and second transverse support beams are rectangular tube beams; the wheel axle is inserted into the corresponding end of the corresponding rectangular tube beam and fixed to the corresponding rectangular tube beam by bolts.
[0013] Furthermore, the buffer pad is a single wooden block or is composed of multiple wooden blocks stacked together.
[0014] Furthermore, the top surface of the buffer pad is provided with anti-slip grooves.
[0015] Compared with the prior art, the beneficial effects of this utility model are as follows:
[0016] The auxiliary wheel device for heavy truck rescue provided by this utility model, through the combined use of a support frame, buffer pads and locking parts, can quickly replace the faulty wheel and provide temporary mobile support for heavy trucks. It solves the problems of traditional rescue methods that require large equipment, have long preparation time and are prone to causing traffic jams. It has the advantages of being quick to install, safe and reliable and applicable to various road conditions, significantly reducing the time that accident vehicles occupy the road and improving road traffic safety.
[0017] Other advantages, objectives, and features of this invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination and study, or may be learned from practice of this invention. The objectives and other advantages of this invention can be realized and obtained through the following description. Attached Figure Description
[0018] Figure 1 This is a schematic diagram of the isometric structure of this utility model;
[0019] Figure 2 for Figure 1 A schematic diagram of the isometric structure after removing the buffer pads and locking components;
[0020] Figure 3 for Figure 2 A schematic diagram of the explosion structure.
[0021] Reference numerals in the attached drawings: 1-Support frame; 101-Longitudinal support beam; 1011-Longitudinal intermediate beam; 1012-First longitudinal sleeve beam; 1013-Second longitudinal sleeve beam; 1014-Limiting baffle; 102-First transverse support beam; 103-Second transverse support beam; 104-First oblique reinforcing plate; 105-Second oblique reinforcing plate; 2-Walking wheel; 201-Wheel axle; 202-Walking wheel body; 3-Buffer pad; 301-Anti-slip groove; 4-Locking component; 5-Locking lug; 501-Locking hole. Detailed Implementation
[0022] The following specific examples illustrate the implementation of this utility model. Those skilled in the art can easily understand other advantages and effects of this utility model from the content disclosed in this specification. This utility model can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this utility model. It should be noted that the illustrations provided in the following embodiments are only for illustrating the basic concept of this utility model. Unless otherwise specified, the following embodiments and features in the embodiments can be combined with each other. It should be noted that in the description of this application, the terms "first," "second," etc., are only used for distinguishing descriptions and should not be construed as indicating or implying relative importance.
[0023] Additionally, it should be noted that, unless otherwise specified, "longitudinal" in the following text refers to the direction along the length of the vehicle body when in use; and "lateral" refers to the direction along the width of the vehicle body when in use.
[0024] Please see Figure 1-3This embodiment discloses an auxiliary wheel device for heavy truck rescue. This device replaces a disabled wheel of a heavy truck during use and includes a support frame 1, a buffer pad 3, and a locking component 4. The support frame 1 is equipped with a traveling wheel 2. The buffer pad 3 is located on the support frame 1 and provides a support point for the axle of the disabled wheel during use. The locking component 4 is used to fix the axle of the disabled wheel to the buffer pad 3. Specifically, the support frame 1 is preferably a welded steel pipe structure, with an overall roughly rectangular shape. The traveling wheel 2 is used to support the road surface and perform the walking function. The buffer pad 3 can be made of hardwood, engineering plastic, or rubber composite material, and its shape is preferably designed as a rectangular block. The locking component 4 can be made of nylon straps or metal chains, etc., and the length of the locking component 4 is selected according to the size of the axle. In practical use, first remove the faulty wheel (including the wheel hub) of the heavy truck from the axle head; then install this auxiliary wheel device at the corresponding axle head and support the axle head on the buffer pad 3; then use the locking device to lock and fix the axle head at the faulty wheel to the buffer pad 3; finally, the faulty vehicle can be towed away directly by a tractor.
[0025] This technical solution, through the coordinated use of a movable support frame 1, buffer pads 3, and locking components 4, can quickly replace a disabled wheel, providing temporary mobile support for heavy trucks. It solves the problems of traditional rescue methods, such as requiring large equipment, long preparation times, and easily causing traffic congestion. It boasts advantages such as rapid installation, safety and reliability, applicability to various road conditions, significantly reducing the time accident vehicles occupy the road, and improving road traffic safety. The traveling wheel 2 provides rolling support, the buffer pads 3 distribute pressure on the axle head and prevent direct metal-to-metal contact, avoiding damage to the axle head during vehicle towing, and the locking components 4 ensure a reliable connection between the device and the vehicle, guaranteeing operational safety. For axles with different ground clearance, only buffer pads of different thicknesses need to be replaced, demonstrating good versatility. Practice shows that this auxiliary wheel device can generally be assembled on-site within 20 minutes, enabling disabled vehicles to move to a safe area at a speed not exceeding 15 km / h.
[0026] In this embodiment, the support frame 1 includes a longitudinal support beam 101 and a first transverse support beam 102 and a second transverse support beam 103 respectively disposed at both ends of the longitudinal support beam 101; four wheels 2 are disposed at both ends of the first transverse support beam 102 and the second transverse support beam 103 respectively; and three buffer pads are placed on top of the longitudinal support beam 101. Specifically, the longitudinal support beam 101 can be made of I-beams or rectangular steel pipes, and its length is designed to be adjustable according to the wheelbase range of heavy-duty trucks. The first transverse support beam 102 and the second transverse support beam 103 preferably use steel sections with the same cross-section and are connected to the longitudinal support beam 101 by welding or bolting to form an H-shaped frame structure. The wheels 2 are mounted on the ends of the transverse support beams via axles 201. The wheels 2 can be solid rubber wheels with bearings or pneumatic tires, and the wheel diameter is recommended to be 300-500mm to ensure ground clearance. The buffer pad 3 is fixed to the center of the upper surface of the longitudinal support beam 101 by bolts or slots, and its thickness is determined by the distance between the upper surface of the longitudinal support beam 101 and the lower surface of the vehicle axle head. Overall, the thickness of the buffer pad 3 should be no less than 80mm to provide effective cushioning. This structure, by symmetrically arranging the traveling wheels 2 at both ends of the transverse support beam, forms a stable four-point support system, which can evenly distribute the truck load. The longitudinal support beam 101, as the main load-bearing component, ensures the overall stability of the frame through its rigid connection. The top positioning design of the buffer pad 3 facilitates docking with the axle head of the disabled wheel 201. Compared to a single-point support structure, this solution significantly improves the device's anti-overturning capability during towing, and is particularly suitable for rescue operations on uneven road surfaces.
[0027] In this embodiment, the longitudinal support beam 101 includes a longitudinal intermediate beam 1011 and a first longitudinal sleeve beam 1012 and a second longitudinal sleeve beam 1013, which are respectively slidably fitted and lockably disposed at both ends of the longitudinal intermediate beam 1011. The first transverse support beam 102 is fixed to the top of the first longitudinal sleeve beam 1012 and can move with the first longitudinal sleeve beam 1012. The second transverse support beam 103 is fixed to the second longitudinal sleeve beam 1013 and can move with the second longitudinal sleeve beam 1013. Specifically, the slidable fitting means that the first longitudinal sleeve beam 1012 and the second longitudinal sleeve beam 1013 form a relatively slidable connection structure with the longitudinal intermediate beam 1011 through a sleeve connection. For example, axial sliding can be achieved by using a rectangular tube nesting fit. The locking setting can be achieved by bolt tightening, pin insertion, or a quick clamping mechanism to fix the position. Furthermore, the first transverse support beam 102 and the first longitudinal sleeve beam 1012, and the second transverse support beam 103 and the second longitudinal sleeve beam 1013 can be rigidly fixed by welding or bolting.
[0028] Therefore, this technical solution, through its telescopically adjustable longitudinal support beam 101 structure, can adapt to the rescue needs of heavy-duty trucks with different axle head sizes. The sliding sleeve structure ensures support strength while allowing for flexible adjustment of the device length, while the locking mechanism ensures structural stability during operation. This design significantly improves the device's adaptability to different vehicle models, solving the problem of limited applicability caused by the non-adjustable size of existing rescue devices. In practice, the adjustment process only requires loosening the locking mechanism, moving the sliding sleeve beam to the desired position, and then relocking it, making the operation convenient and highly reliable.
[0029] In this embodiment, the support frame 1 further includes a first oblique reinforcing plate 104 and a second oblique reinforcing plate 105 respectively disposed at both ends of the longitudinal support beam 101; the first oblique reinforcing plate 104 forms a triangular reinforcing structure with the first longitudinal sleeve beam 1012 and the first transverse support beam 102; the second oblique reinforcing plate 105 forms a triangular reinforcing structure with the second longitudinal sleeve beam 1013 and the second transverse support beam 103. Specifically, the oblique reinforcing plates can be welded from metal plates, and their thickness can be selected from 5-10mm steel plates according to the load-bearing requirements. Thus, by setting the oblique reinforcing plates to form a triangular stable structure, the overall rigidity and deformation resistance of the support frame 1 are effectively improved. When the auxiliary wheel device bears the load of the axle head of a heavy truck, the oblique reinforcing plates can distribute part of the load to the transverse support beam, avoiding local stress concentration in the longitudinal support beam 101. This structural design significantly improves the stability of the device during towing, ensures that the faulty wheel can be reliably supported, and reduces the risk of device failure due to frame deformation.
[0030] In this embodiment, there are two sets of longitudinal support beams 101. Limiting baffles 1014 are fixed to the outer sides of each set of longitudinal support beams 101 laterally, and the buffer pad 3 is located between the two limiting baffles 1014. Specifically, the longitudinal support beams 101 are arranged in a double-set parallel configuration. Each set of longitudinal support beams 101 consists of a longitudinal intermediate beam 1011 and sleeve beams that can be slidably adjusted at both ends. Vertically upward limiting baffles 1014 are welded to the outer sides of the two sets of longitudinal support beams 101. These baffles can be made of steel plates with a thickness of 5-8mm. The buffer pad 3 is precisely confined within the channel space formed by the two limiting baffles 1014, wherein the distance between the two limiting baffles 1014 is slightly larger than the width of the buffer pad 3 to ensure convenient installation of the buffer pad 3.
[0031] Therefore, this technical solution effectively solves the problem of lateral displacement that may occur when a single-beam structure carries the axle head of a heavy truck by combining a double longitudinal beam structure and a limiting baffle 1014. The limiting baffle 1014 not only functions as a positioning buffer pad 3, but also prevents lateral slippage of the pad due to vibration during towing. The symmetrical load-bearing structure formed by the two sets of longitudinal support beams 101 ensures that the pressure on the axle head is evenly distributed across the four wheels 2, significantly improving the stability of the device under dynamic load conditions. This design is particularly suitable for the complex stress conditions of heavy trucks being towed on inclined roads or curves, ensuring the reliability of the support system through mechanical limiting.
[0032] In this embodiment, locking lugs 5 are fixedly provided on the first transverse support beam 102 and the second transverse support beam 103, and each locking lug 5 is provided with a locking hole 501. The locking component 4 is a locking rope, which passes through the locking hole 501 to complete the binding and installation of the axle head and the buffer pad 3 at the faulty wheel. Specifically, the locking lugs 5 are fixed to the transverse support beam by welding or bolting. The locking hole 501 is a through hole structure, and the hole diameter is designed according to the diameter of the locking rope, usually 10-20mm. The locking rope is preferably made of high-strength nylon rope or steel wire rope, and its length can be adjusted according to actual needs. Quick-lock buckles can be provided at both ends for easy operation. More specifically, multiple locking lugs 5 are provided here. Thus, this technical solution achieves rapid fixing of the axle head 201 of the faulty wheel by setting locking lugs 5 with locking holes 501 in conjunction with locking ropes. The flexibility of the locking rope can adapt to axle heads of different sizes, and the multi-point fixing ensures the reliability of the connection. This structure is easy to install and highly adaptable, enabling the auxiliary wheel device to be installed and fixed quickly at the rescue site, which helps to shorten the time that heavy trucks occupy the road when they break down.
[0033] In this embodiment, the traveling wheel 2 includes an axle 201 and a traveling wheel 2 body rotatably mounted on the axle 201. The axles 201 of the four traveling wheels 2 are detachably and fixedly connected to the two ends of the first transverse support beam 102 and the second transverse support beam 103, respectively. Specifically, the axle 201 and the traveling wheel 2 body are rotatably connected through bearings, and the traveling wheel 2 body is made of high-strength rubber material to withstand the load of heavy trucks. The detachable and fixed connection methods include, but are not limited to: using a bolt fastening structure, with threaded holes machined at the end of the axle 201 and fixed to the transverse support beam with bolts; using a pin-type structure, with through holes opened at corresponding positions of the axle 201 and the transverse support beam and locked with pins; and using a quick-release buckle structure, with quick installation and removal of the axle 201 through spring buckles. Among these, the bolt fastening structure has the characteristics of reliable connection and high load-bearing capacity, and can be used as a preferred embodiment. Thus, this technical solution realizes the quick replacement and maintenance of the traveling wheels 2 through a modular and detachable design. When a single wheel 2 is damaged, it can be replaced simply by removing the corresponding axle 201, without having to replace the entire support frame 1. The modular structure reduces transportation and storage space requirements, while also facilitating the replacement of different sizes of wheels 2 to meet different load requirements.
[0034] In this embodiment, both the first transverse support beam 102 and the second transverse support beam 103 are rectangular tubular beams; the wheel axle 201 is inserted into the corresponding end of the corresponding rectangular tubular beam and fixed to the corresponding rectangular tubular beam by bolts. Specifically, the rectangular tubular beam adopts a hollow rectangular cross-section structure, which has high bending stiffness and torsional stiffness. The wheel axle 201 is positioned with the rectangular tubular beam by an insertion method, wherein the end of the wheel axle 201 can be processed into a square cross-section that matches the inner cavity of the rectangular tubular beam. Bolt fixing can adopt a through bolt connection, that is, a through hole is opened in the side wall of the rectangular tubular beam, and a through hole is set at the corresponding position of the wheel axle 201, and fastening is achieved by bolts and nuts. Thus, this technical solution realizes the quick disassembly and reliable fixing of the traveling wheel 2 through the insertion and matching structure of the rectangular tubular beam and the wheel axle 201. The structural characteristics of the rectangular tubular beam can effectively distribute the force on the wheel axle 201 and avoid local stress concentration. The bolt connection method facilitates on-site adjustment and maintenance, while ensuring connection strength.
[0035] In this embodiment, the buffer pad 3 is a single wooden block or composed of multiple stacked wooden blocks. Specifically, the buffer pad 3 is made of wood, where a single wooden block refers to a pad formed from a whole piece of wood, while a pad composed of multiple stacked wooden blocks is formed by combining several pieces of wood through gluing or mechanical connection. Thus, this technical solution, through the elastic deformation characteristics of the wooden buffer pad 3, can effectively absorb the impact load between the vehicle axle head and the support frame 1, while the natural texture of the wood provides good frictional properties to prevent relative slippage. Furthermore, the wooden pad has the advantages of low cost, convenient processing, and easy on-site replacement.
[0036] In this embodiment, the top surface of the buffer pad 3 is provided with an anti-slip groove 301. The anti-slip groove 301 is preferably designed as a transverse groove structure, but a grid-like or wavy surface texture can also be used. Specifically, the depth of the anti-slip groove 301 can be in the range of 2-5 mm, and the groove spacing is controlled between 10-20 mm. Furthermore, the cross-sectional shape of the anti-slip groove 301 can be V-shaped or U-shaped, etc. Therefore, by providing the anti-slip groove 301 on the top surface of the buffer pad 3, the frictional force between the buffer pad 3 and the contact surface with the axle head 201 of the disabled wheel can be effectively increased, preventing relative slippage during towing. Specifically, when the auxiliary wheel device bears the weight of a heavy truck, the anti-slip groove 301 structure can generate greater static friction, ensuring stable contact between the axle head and the buffer pad 3. Compared with a smooth surface buffer pad 3, the structure with the anti-slip groove 301 significantly improves the fixing effect and reduces safety hazards caused by insufficient friction during towing.
[0037] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model and are not intended to limit it. Although this utility model has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of this utility model without departing from the spirit and scope of the technical solutions of this utility model, and all such modifications or substitutions should be covered within the scope of the claims of this utility model.
Claims
1. An auxiliary wheel device for heavy truck rescue, characterized in that, include: A support frame, wherein the support frame is provided with wheels; A buffer pad is installed on the support frame to provide a support point for the axle head at the faulty wheel during use; The locking element is used to secure the axle head at the faulty wheel to the buffer pad.
2. The auxiliary wheel device for heavy truck rescue according to claim 1, characterized in that: The support frame includes a longitudinal support beam and a first transverse support beam and a second transverse support beam respectively disposed at both ends of the longitudinal support beam; There are four walking wheels, which are respectively set at both ends of the first and second transverse support beams; the buffer pad is placed on the top of the longitudinal support beam.
3. The auxiliary wheel device for heavy truck rescue according to claim 2, characterized in that: The longitudinal support beam includes a longitudinal intermediate beam, and a first longitudinal sleeve beam and a second longitudinal sleeve beam that are respectively slidably sleeved and lockably disposed at both ends of the longitudinal intermediate beam. The first transverse support beam is fixed to the top of the first longitudinal sleeve beam and can move with the first longitudinal sleeve beam; the second transverse support beam is fixed to the second longitudinal sleeve beam and can move with the second longitudinal sleeve beam.
4. The auxiliary wheel device for heavy truck rescue according to claim 3, characterized in that: The support frame also includes a first inclined reinforcing plate and a second inclined reinforcing plate respectively disposed at both ends of the longitudinal support beam; The first oblique reinforcing plate forms a triangular reinforcing structure with the first longitudinal sleeve beam and the first transverse support beam; The second oblique reinforcing plate forms a triangular reinforcing structure with the second longitudinal sleeve beam and the second transverse support beam.
5. The auxiliary wheel device for heavy truck rescue according to claim 3, characterized in that: The longitudinal support beams consist of two sets; Limiting baffles are fixed on the outer sides of the two sets of longitudinal support beams in the transverse direction, and the buffer pad is located between the two limiting baffles.
6. The auxiliary wheel device for heavy truck rescue according to claim 3, characterized in that: Locking lugs are fixedly provided on the first transverse support beam and the second transverse support beam, and locking holes are provided on the locking lugs. The locking component is a locking rope, which is threaded through the locking hole to complete the binding and installation of the axle head and the buffer pad at the faulty wheel.
7. The auxiliary wheel device for heavy truck rescue according to claim 2, characterized in that: The traveling wheel includes an axle and a traveling wheel body rotatably mounted on the axle; The axles of the four wheels are detachably and fixedly connected to the two ends of the first and second transverse support beams, respectively.
8. The auxiliary wheel device for heavy truck rescue according to claim 7, characterized in that: Both the first and second transverse support beams are rectangular tubular beams; The axle is inserted into the corresponding end of the corresponding rectangular tube beam and fixed to the corresponding rectangular tube beam by bolts.
9. The auxiliary wheel device for heavy truck rescue according to claim 1, characterized in that: The buffer pad is a single wooden block or made up of multiple wooden blocks stacked together.
10. The auxiliary wheel device for heavy truck rescue according to claim 9, characterized in that: The top surface of the buffer pad is provided with anti-slip grooves.