Device for quickly releasing rear axle brake of tank type refueling vehicle

Abstract

The invention discloses a device for rapidly relieving rear axle braking of a tank type refueling truck, and belongs to the technical field of vehicle braking, the device comprises a pneumatic control assembly, the pneumatic control assembly comprises a reversing valve, a selection valve and an air source connecting end, the air inlet end of the reversing valve is connected with the air source connecting end, and the air outlet end of the reversing valve is connected with an air inlet of the selection valve; and an air outlet of the selector valve is communicated with a rear axle parking brake control air path of the tank-type refueling vehicle. By means of the pneumatic control assembly, under the condition that an original vehicle rear axle parking braking system is completely invalid, parking braking of the tank-type refueling vehicle can still be rapidly relieved, then the vehicle can complete emergency movement, the tank-type refueling vehicle is prevented from being detained in special operation areas such as an airport apron with aviation fuel guarantee, and the service life of the tank-type refueling vehicle is prolonged. The situation that traffic jam is caused by the fact that the traffic order of an operation site is damaged is prevented, and the problems that propelling of oil guarantee related operation is blocked, and operation delay occurs are solved.

Description

Technical Field

[0001] This invention relates to the field of vehicle braking technology, and in particular to a device for quickly releasing the rear axle brake of a tanker refueling truck. Background Technology

[0002] Tank refueling trucks are specialized vehicles commonly used in operations such as aviation fuel supply. The rear axle parking brake system is a crucial component for ensuring parking safety and facilitating operational scheduling. Currently, most tank refueling trucks in the industry employ a spring brake structure based on the air brake principle, such as... Figure 5 As shown, it typically includes components such as a parking air tank, a parking relay valve, a rear brake chamber, and a parking brake hand valve. The parking brake is achieved by relying on spring force, that is, the brake release is completed by regulating the air pressure of the air circuit system. The normal operation of this braking system is directly related to the parking safety of the tanker refueling truck and the scheduling flexibility during operation.

[0003] The existing rear axle parking brake system of tanker refueling trucks has a technical defect in actual use: the brake cannot be released normally. For example, due to the failure of the air circuit system and related components, the air circuit is prone to leakage, resulting in insufficient air pressure, which cannot overcome the spring force to release the brake. At the same time, failure of core components such as the parking relay valve and brake chamber will cause the air circuit on / off control to fail. The failure to release the interlocking point of the upper body and the emergency interlocking point will also cause the parking brake to release failure. Multiple fault factors can cause the rear axle parking brake to fail to act normally when it needs to be released, which has become a common problem of the existing braking system.

[0004] The failure of the rear axle parking brake of a tanker refueling truck to release properly will directly prevent the vehicle from moving. In special operating areas such as the apron, the vehicle's congestion will not only disrupt the traffic order at the work site and cause traffic jams, but will also seriously interfere with the normal progress of related operations such as fuel supply. This can easily lead to delays in subsequent operations and bring great difficulties to on-site operation scheduling and emergency response. The existing rear axle parking brake system of tanker refueling trucks lacks effective response capabilities for this type of failure and is difficult to meet the emergency use needs in actual operations. Summary of the Invention

[0005] The main objective of this invention is to overcome the deficiencies of the existing technology and provide a device for quickly releasing the rear axle parking brake of a tanker truck, which is compatible with the original vehicle structure, effectively enables emergency vehicle movement, and avoids operational obstruction in the work area.

[0006] To achieve the above objectives, the present invention provides a device for quickly releasing the rear axle brake of a tanker refueling truck, comprising a pneumatic control assembly installed on the tanker refueling truck and connected to the rear axle parking brake control air circuit. The pneumatic control assembly includes a reversing valve, a selector valve, and an air source connection terminal. The air inlet of the reversing valve is connected to the air source connection terminal, which is used to connect to an external air source. The air outlet of the reversing valve is connected to the air inlet of the selector valve, and the air outlet of the selector valve is connected to the rear axle parking brake control air circuit of the tanker refueling truck.

[0007] Preferably, the reversing valve is a two-position three-way manual pneumatic control valve, and the reversing valve is provided with a handle; the selector valve is a shuttle valve, the selector valve has two air inlets, and the air outlet of the reversing valve is connected to either air inlet of the shuttle valve.

[0008] Preferably, it also includes a connecting seat, which is detachably connected to the frame of the tanker refueling truck, and the connecting seat is used to install the pneumatic control assembly.

[0009] Preferably, the connecting seat includes a support and a slider. The support has a groove for the frame of the tanker refueling truck to extend into. The slider is slidably installed in the groove so as to clamp or loosen the frame of the tanker refueling truck by moving the slider closer to or away from the support.

[0010] Preferably, the connecting seat further includes an adjusting rod, which is rotatably installed in the groove along the extension direction of the support and threadedly engaged with the slider. One end of the adjusting rod passes through the support and is provided with a handwheel, and the other end of the adjusting rod is rotatably connected to the support.

[0011] Preferably, a limiting groove is formed at the bottom of the groove along the extending direction of the support, and a positioning protrusion is formed on the bottom surface of the slider to engage with the limiting groove.

[0012] Preferably, flexible pads are provided on the side of the slider opposite to the support.

[0013] Beneficial effects:

[0014] 1. The present invention provides a device for quickly releasing the rear axle brake of a tanker refueling truck. Through a pneumatic control component, the device enables the tanker refueling truck to quickly release the parking brake even when the original rear axle parking brake system completely fails, thereby allowing the vehicle to move in an emergency. This effectively solves the core problem of vehicle immobility due to brake failure in the prior art, and avoids the tanker refueling truck from being stuck in special operating areas such as the apron for aviation fuel supply. It prevents the disruption of traffic order at the work site and the occurrence of traffic congestion, and avoids the problems of obstruction and delay of fuel supply-related operations, thus meeting the emergency use needs of tanker refueling trucks in actual operation.

[0015] 2. The device for quickly releasing the rear axle brake of a tanker refueling truck of the present invention can realize the function of emergency brake release by simply adding a pneumatic control component. It does not require modification of the main structure of the original rear axle parking brake system of the tanker refueling truck, and has good compatibility with the original vehicle braking system. This provides convenience for the actual installation and use of the device, and also lays the foundation for subsequent structural refinement and functional optimization of the device. The structural design is simple and reasonable. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the installation of a device for quickly releasing the rear axle brake of a tanker refueling truck and the chassis of the tanker refueling truck, according to an embodiment of the present invention.

[0018] Figure 2 This is a schematic diagram of the structure of a device for quickly releasing the rear axle brake of a tanker truck according to an embodiment of the present invention from a first-view perspective.

[0019] Figure 3 This is a schematic diagram of the structure of a device for quickly releasing the rear axle brake of a tanker truck according to an embodiment of the present invention from a second perspective.

[0020] Figure 4 This is a schematic diagram illustrating the connection principle between a device for quickly releasing the rear axle brake of a tanker refueling truck and the air circuit for controlling the parking brake of the rear axle of the tanker refueling truck, according to an embodiment of the present invention.

[0021] Figure 5 This is a schematic diagram of the connection principle of the air circuit for the parking brake control of the rear axle of a tanker refueling truck in the existing technology.

[0022] In the diagram: 100-frame; 1-reversing valve; 2-selector valve; 3-air source connection end; 4-connecting seat; 5-support; 6-slider; 7-groove; 8-adjusting rod; 9-handwheel; 10-limiting groove; 11-positioning protrusion; 12-flexible pad. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0024] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0025] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0026] In the description of this application, it should be noted that the use of terms such as "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer" to indicate orientation or positional relationships is based on the orientation or positional relationships shown in the accompanying drawings, or the orientation or positional relationships commonly used when the product is in use. These terms are used solely for the convenience of describing this application and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application. Furthermore, the use of terms such as "first" and "second" in the description of this application is only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0027] Furthermore, the use of terms such as "horizontal" and "vertical" in the description of this application does not imply that the component is required to be absolutely horizontal or suspended, but rather that it may be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but rather that it may be slightly tilted.

[0028] In the description of this application, it should also be noted that, unless otherwise expressly specified and limited, the terms "set up," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0029] Example 1:

[0030] This invention proposes a device for quickly releasing the rear axle brake of a tanker refueling truck.

[0031] In one embodiment of the present invention, a device for quickly releasing the rear axle brake of a tanker refueling truck includes a pneumatic control assembly disposed on the tanker refueling truck and connected to the rear axle parking brake control air circuit. The pneumatic control assembly includes a reversing valve 1, a selector valve 2, and an air source connection end 3. The air inlet end of the reversing valve 1 is connected to the air source connection end 3, which is used to connect to an external air source. The air outlet end of the reversing valve 1 is connected to the air inlet of the selector valve 2, and the air outlet of the selector valve 2 is connected to the rear axle parking brake control air circuit of the tanker refueling truck.

[0032] Working principle: such as Figure 4 As shown, the pneumatic control component integrates a reversing valve 1, a selector valve 2, and an air source connection terminal 3. The air inlet of the reversing valve 1 is connected to the air source connection terminal 3, which can be connected to an external air source. The air outlet of the reversing valve 1 is connected to the air inlet of the selector valve 2, and the air outlet of the selector valve 2 is connected to the rear axle parking brake control air circuit of the tanker refueling truck, thus forming an emergency control air circuit independent of the original vehicle braking air circuit. This can solve the technical defects of the rear axle parking brake system of the tanker refueling truck in the existing technology.

[0033] Specifically, because existing tank-type refueling trucks mostly use spring brake structures based on the principle of air brakes for the rear axle parking brake, they are prone to insufficient air pressure due to leaks in the original vehicle's air circuit, thus failing to reliably overcome the spring force and achieve brake release. However, in this embodiment, such as... Figure 1 and Figure 4As shown, since the air source connection terminal 3 can be connected to an external air source, the pneumatic power of the entire device is completely independent of the original vehicle's air tank and air circuit system. Even if the original vehicle's air circuit has leakage or insufficient air pressure, the external air source can still provide stable and sufficient air pressure for brake release, thus avoiding the problem of brake release failure caused by original vehicle air source related faults from the root. At the same time, in response to the problem in the prior art that the original vehicle's air circuit on / off control fails due to the failure of the parking relay valve, rear brake chamber, or the failure of the upper structure and emergency interlock point release, this embodiment constructs an emergency air circuit channel independent of the original vehicle's brake valve and interlock point through the orderly connection of the reversing valve 1, the selector valve 2, and the rear axle parking brake control air circuit. This channel is not affected by the failure of the original vehicle's valve components or the failure of the interlock point, and can stably transmit the air pressure of the external air source to the parking brake control air circuit, thereby successfully overcoming the spring force and completing the brake release, making it safe and reliable to use.

[0034] Understandably, this embodiment, through a pneumatic control component, enables the tanker refueling truck to quickly release the parking brake even when the original rear axle parking brake system completely fails, allowing the vehicle to move in an emergency. This effectively solves the core problem of vehicle immobility due to brake failure in existing technologies, preventing the tanker refueling truck from being stranded in special operational areas such as airport tarmacs for aviation fuel supply. It prevents disruption of traffic order and congestion at the work site, and avoids delays and obstructions in fuel supply operations, meeting the emergency use needs of tanker refueling trucks during actual operations. Furthermore, this invention's device for quickly releasing the rear axle brake of a tanker refueling truck achieves emergency brake release simply by adding a pneumatic control component, without requiring modifications to the main structure of the original rear axle parking brake system. It exhibits good compatibility with the original braking system, facilitating the actual installation and use of the device, and laying the foundation for subsequent structural refinement and functional optimization. The structural design is simple and reasonable.

[0035] Example 2:

[0036] This embodiment, based on Embodiment 1, further refines the valve structure of the pneumatic control component to optimize the operability and adaptability of the device, meeting the emergency operation needs of tanker refueling trucks. Specifically, as follows... Figures 1 to 3 As shown, the reversing valve 1 is a two-position three-way manual pneumatic control valve with a handle; the selector valve 2 is a shuttle valve with two air inlets, and the air outlet of the reversing valve 1 is connected to either air inlet of the shuttle valve.

[0037] In this embodiment, the reversing valve 1 can be a two-position three-way manual pneumatic control valve, allowing operators to manually move the valve core by pulling the handle, quickly switching the air circuit on / off and direction. The operation is simple and direct, requiring no additional electrical control components, and is suitable for rapid operation in emergency situations on the apron. Furthermore, the selector valve 2 can be a shuttle valve. The shuttle valve's dual-inlet structure allows it to simultaneously connect to the external air source transmitted by the reversing valve 1 and the original vehicle's parking brake control air circuit. The shuttle valve can automatically select the air circuit with the higher pressure, ensuring stable transmission of the external air source to the parking brake control air circuit for brake release, while also adapting to the original vehicle's air circuit without affecting the normal operation of the original vehicle's braking system. In addition, connecting the outlet of the reversing valve 1 to any one of the inlets of the shuttle valve provides flexibility for the installation and commissioning of the device, eliminating the need for fixed air circuit connection positions and further improving the device's compatibility with different sizes of tanker refueling trucks.

[0038] Example 3:

[0039] This embodiment, based on embodiment 2, adds a connecting seat 4 for mounting the pneumatic control components. The connecting seat 4 and the frame 100 of the tanker refueling truck are detachably connected. The pneumatic control components are integrated and mounted on the connecting seat 4, achieving a stable assembly between the pneumatic control components and the frame 100. Specifically, as... Figures 1 to 3 As shown, it also includes a connecting seat 4, which is detachably connected to the frame 100 of the tanker refueling truck. The connecting seat 4 is used to install pneumatic control components.

[0040] In this embodiment, the connecting seat 4 serves as the connecting carrier between the pneumatic control component and the vehicle frame 100. It integrates and fixes the reversing valve 1, shuttle valve, and air source connection end 3, thereby avoiding problems such as loose air circuit connections and inconvenient operation caused by the scattered installation of various components. This ensures that the pneumatic control component maintains the overall structural stability during vehicle operation or emergency operation. Simultaneously, since the connecting seat 4 is detachably connected to the vehicle frame 100 of the tanker refueling truck, no destructive processing such as welding or drilling is required on the vehicle frame 100. This meets the design requirements for compatibility between the device and the original vehicle structure, significantly reducing the installation difficulty of the device. Furthermore, the installation position can be flexibly adjusted according to actual operational needs to adapt to the vehicle frame 100 structure of different specifications of tanker refueling trucks. In addition, the pneumatic control component can be installed on the connecting seat 4 using a detachable structure such as a threaded connection, facilitating subsequent disassembly, assembly, and maintenance of the pneumatic control component. This effectively improves the maintenance convenience of the device and further adapts to the actual operational needs of tanker refueling trucks.

[0041] Example 4:

[0042] This embodiment, based on embodiment 3, further refines the specific structure of the connecting seat 4, optimizing its compatibility and stability with the tanker truck frame 100. Specifically, as follows... Figure 2 and Figure 3 As shown, the connecting seat 4 includes a support 5 and a slider 6. The support 5 has a groove 7 for the tanker refueling truck frame 100 to extend into. The slider 6 is slidably installed in the groove 7 so that the tanker refueling truck frame 100 can be clamped or released by moving the slider 6 closer to or away from the support 5.

[0043] In this embodiment, the connecting seat 4 includes a support 5 and a slider 6, and the support 5 has a groove 7. The tanker truck frame 100 can directly extend into the groove 7, while the slider 6 is installed inside the groove 7 in a limiting sliding manner. This allows the operator to clamp and release the frame 100 by driving the slider 6 to move closer to or away from the support 5 within the groove 7, making it convenient to use. Obviously, the groove 7 can effectively lock the frame 100, making the connection between the connecting seat 4 and the frame 100 more precise and avoiding misalignment during installation. At the same time, in this embodiment, the installation and removal of the connecting seat 4 on the frame 100 can be completed simply by the limiting sliding of the slider 6, without the need for additional processing of the frame 100. This retains the convenient advantage of the detachable connecting seat 4 and can adapt to frame 100s of different widths, further improving the universality and installation stability of the device.

[0044] Example 5:

[0045] This embodiment further optimizes the structure of the connecting seat 4 based on embodiment 4 by adding an adjusting rod 8 and a handwheel 9, thereby improving the convenience of connecting the connecting seat 4 to the frame 100 and the clamping stability. Specifically, as follows... Figure 2 As shown, the connecting seat 4 also includes an adjusting rod 8. The adjusting rod 8 is rotatably installed in the groove 7 along the extension direction of the support 5 and is threadedly engaged with the slider 6. One end of the adjusting rod 8 passes through the support 5 and is provided with a handwheel 9. The other end of the adjusting rod 8 is rotatably connected to the support 5.

[0046] In this embodiment, the adjusting rod 8 is rotatably installed inside the groove 7 along the extension direction of the support 5, and the adjusting rod 8 and the slider 6 are threadedly engaged. One end of the adjusting rod 8 passes through the support 5 and is equipped with a handwheel 9, while the other end is rotatably connected to the support 5. This allows the operator to rotate the adjusting rod 8 by turning the handwheel 9. With the transmission effect of the threaded engagement, the slider 6 is driven to move smoothly along the groove 7 towards or away from the support 5. The entire operation can be completed without the need for additional tools to clamp and release the frame 100. The operation method is simple and labor-saving, and it is suitable for the operational needs of emergency operations on the apron. At the same time, the threaded engagement has good self-locking performance. After the slider 6 clamps the frame 100, it will not loosen or shift due to vehicle movement or vibration, thus ensuring that the pneumatic control components always maintain a stable installation state. Furthermore, since both ends of the adjusting rod 8 are rotatably connected to the support 5, the smoothness of the adjusting rod 8 during rotation can be ensured. The handwheel 9 increases the operating force surface for the operator, further reducing the difficulty of manual operation and making the disassembly, assembly, and position adjustment of the device more convenient and efficient. In addition, it should be noted that a locking nut can be installed on the end of the adjusting rod 8 that is not equipped with a handwheel 9. The threaded engagement between the locking nut and the adjusting rod 8 can further prevent the adjusting rod 8 from loosening due to the vibration of the frame 100, and significantly improve the installation stability of the adjusting rod 8.

[0047] Example 6:

[0048] This embodiment further optimizes the structure of the connecting seat 4 based on embodiment 5. A matching limiting groove 10 and a positioning protrusion 11 are added between the groove 7 and the slider 6, improving the stability and accuracy of the slider 6's sliding. Specifically, as shown... Figure 2 and Figure 3 As shown, a limiting groove 10 is formed at the bottom of the groove 7 along the extension direction of the support 5, and a positioning protrusion 11 is formed on the bottom surface of the slider 6 to engage with the limiting groove 10.

[0049] In this embodiment, a limiting groove 10 is formed at the bottom of the groove 7 along the extension direction of the support 5, and a positioning protrusion 11 is integrally formed on the bottom surface of the slider 6. The positioning protrusion 11 and the limiting groove 10 form an interlocking engagement, so that the slider 6 can only slide in a straight line along the extension direction of the limiting groove 10. This effectively avoids the slider 6 from deviating, rotating or getting stuck when sliding in the groove 7, and ensures that when the adjusting rod 8 rotates, the slider 6 can smoothly approach or move away from the support 5, making the clamping operation of the frame 100 more accurate and stable.

[0050] Example 7:

[0051] This embodiment further optimizes the structure of the connecting seat 4 based on embodiment 6. Flexible pads 12 are respectively provided on the side of the slider 6 opposite to the support 5, which takes into account both the stability of the clamping of the connecting seat 4 and the protection of the frame 100. Specifically, as Figure 2 and Figure 3 As shown, flexible pads 12 are respectively provided on the side of the slider 6 opposite to the support 5.

[0052] In this embodiment, the flexible pad 12 is fitted onto the clamping surfaces of the slider 6 and the support 5, replacing the direct hard contact between the slider 6 and the support 5 and the frame 100. This effectively buffers the squeezing force during clamping when the operator rotates the handwheel 9 to drive the slider 6 to clamp the frame 100, preventing scratches, dents, and other damage to the surface of the frame 100 caused by hard contact. It also reduces wear on the clamping surfaces of the slider 6 and the support 5, extending the overall service life of the connecting seat 4. Furthermore, the elastic properties of the flexible pad 12 increase the friction between the clamping surfaces of the slider 6 and the support 5 and the outer wall of the frame 100, further improving the fit and stability of the connecting seat 4 after clamping the frame 100. This effectively prevents slight displacement caused by vibration during vehicle operation, ensuring that the pneumatic control components are always in a stable installation state, and preventing loose air circuit connections from affecting brake release operations. The structural design is simple and reasonable.

[0053] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A device for quickly releasing the rear axle brake of a tanker refueling truck, characterized in that, The pneumatic control assembly includes a reversing valve (1), a selector valve (2), and an air source connection end (3). The air inlet of the reversing valve (1) is connected to the air source connection end (3), which is used to connect to an external air source. The air outlet of the reversing valve (1) is connected to the air inlet of the selector valve (2), and the air outlet of the selector valve (2) is connected to the rear axle parking brake control air circuit of the tanker refueling truck.

2. The device for quickly releasing the rear axle brake of a tanker truck according to claim 1, characterized in that, The reversing valve (1) is a two-position three-way manual pneumatic control valve, and the reversing valve (1) is provided with a handle; the selection valve (2) is a shuttle valve, the selection valve (2) has two air inlets, and the air outlet of the reversing valve (1) is connected to any one of the air inlets of the shuttle valve.

3. The device for quickly releasing the rear axle brake of a tanker refueling truck according to claim 2, characterized in that, It also includes a connecting seat (4), which is detachably connected to the frame of the tanker refueling truck, and the connecting seat (4) is used to install the pneumatic control assembly.

4. The device for quickly releasing the rear axle brake of a tanker refueling truck according to claim 3, characterized in that, The connecting seat (4) includes a support (5) and a slider (6). The support (5) has a groove (7) for the frame of the tanker refueling truck to extend into. The slider (6) is slidably installed in the groove (7) so as to clamp or loosen the frame of the tanker refueling truck by moving the slider (6) closer to or away from the support (5).

5. The device for quickly releasing the rear axle brake of a tanker truck according to claim 4, characterized in that, The connecting seat (4) also includes an adjusting rod (8), which is rotatably installed in the groove (7) along the extension direction of the support (5) and threadedly engaged with the slider (6). One end of the adjusting rod (8) passes through the support (5) and is provided with a handwheel (9), and the other end of the adjusting rod (8) is rotatably connected to the support (5).

6. The device for quickly releasing the rear axle brake of a tanker truck according to claim 5, characterized in that, The bottom of the groove (7) is provided with a limiting groove (10) along the extension direction of the support (5), and a positioning protrusion (11) is formed on the bottom surface of the slider (6) to engage with the limiting groove (10).

7. A device for quickly releasing the rear axle brake of a tanker truck according to claim 6, characterized in that, Flexible pads (12) are respectively provided on the side of the slider (6) opposite to the support (5).

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