Crowbar type chain tensioner

Abstract

The invention provides a crowbar type chain tensioner, and belongs to the technical field of logistics transportation instruments. The chain type tensioner solves the problems that an existing chain type tensioner product is large in size and high in manufacturing cost, and meanwhile larger pre-tightening force can be achieved. The crowbar type chain tensioner comprises a main support, a chain wheel connected to the main support and a chain collecting support capable of driving the chain wheel to rotate during swinging, a chain is wound around the chain wheel, the chain collecting support is in a U-shaped plate shape, the open end of the chain collecting support is rotationally connected to the chain wheel, and the closed end of the chain collecting support is fixedly connected with a crowbar sleeve. One end of the crowbar sleeve faces the chain wheel, and the crowbar sleeve is perpendicular to the chain wheel. When the tensioner is used, a user can achieve pre-tightening of the tensioner more easily through the crowbar, so that operation is more labor-saving and convenient, and larger pre-tightening force can be achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of logistics transportation equipment and relates to a crowbar type chain tensioner. Background Art

[0002] A chain tensioner is a device that uses a chain to secure cargo. It has the advantages of high rated load, stable cargo fixation, and long service life. In the process of transporting some heavy cargo such as steel coils and cars, the chain tensioner can well achieve stable fixation of cargo, prevent the movement of cargo due to bumps, vibrations or collisions during transportation, and ensure the safety of transportation.

[0003] At present, conventional chain tensioners are all equipped with a handle for holding by hand. By operating the handle of the chain tensioner, the sprocket is driven to move, so that the chain is gradually tightened, so that the goods on the truck can be fixed. For example, a chain tensioner disclosed in a patent document (application number: 201110112148.0) is composed of a body, a handle, a gear plate, a handle, a chain and a rotating shaft. The handle is hinged to the body through the rotating shaft, and a ratchet is fixedly connected to the rotating shaft. The gear plate is movably connected to the body and the gear plate is embedded in the ratchet. The handle is movably connected to the handle and the handle is embedded in the ratchet. The middle part of the chain is located in the body and is wound around the rotating shaft. Both ends of the chain extend out of the body and a hook 2 is fixedly connected to one end of the chain. The existing handle-type chain tensioner has the following shortcomings in actual use:

[0004] 1. In a handle-type chain tensioner, the handle is a mechanical component used to apply force, so a sufficient lever length is required to apply sufficient force for binding operation. Therefore, the handle of the tensioner is usually made longer, which will result in a larger overall size of the tensioner, which is not convenient to carry or transport.

[0005] 2. For the handle type chain tensioner, since the handle of the tensioner usually includes two side pieces arranged opposite to each other to form a handle rod, and the tail end of the handle rod is sleeved or covered with a plastic handle sleeve, the handle of the tensioner usually has a more complicated structure, thus requiring a more complicated process flow and higher material cost, which leads to the problem of high manufacturing cost of the handle type chain tensioner.

[0006] At present, in order to solve the disadvantages of large product size and high cost of existing tensioners, the conventional technical means adopted are:

[0007] 1. In terms of product size design, a retractable handle structure is used. When operating, the handle is pulled outward to make the handle longer to make the operation easier. After the handle is retracted inward, the size of the product can be reduced. For example, the patent document discloses a "retractable handle of a tensioner (application number: 201820507683.3)";

[0008] 2. In terms of cost reduction, cost reduction is currently usually achieved from structural and process considerations, such as through integrated design, directly using a metal handle and molding the handle grip part into a cylindrical shape, thereby eliminating the handle cover and reducing the material and process costs of the plastic-coated handle cover.

[0009] 3. In terms of reducing costs, unnecessary curves and complex shapes are currently reduced in the handle structure design, and straight lines or simple geometric shapes are used to reduce processing difficulty and cost. Summary of the invention

[0010] The purpose of the present invention is to address the above problems in the existing technology and propose a crowbar type chain tensioner. The present invention solves the problems of large product size and high manufacturing cost of the existing chain type tensioner, and can achieve greater preload force.

[0011] The objective of the present invention can be achieved through the following technical solutions: a crowbar type chain tensioner, comprising a main bracket, a sprocket connected to the main bracket and a chain collecting bracket capable of driving the sprocket to rotate when swinging, a chain being wound around the sprocket, characterized in that the chain collecting bracket is in a U-shaped plate shape and the open end of the chain collecting bracket is rotatably connected to the sprocket, a closed end of the chain collecting bracket is fixedly connected to a crowbar sleeve, one end of the crowbar sleeve faces the sprocket and the crowbar sleeve is perpendicular to the sprocket.

[0012] Compared with the existing conventional chain tensioners, the present crowbar-type chain tensioner adopts a crowbar sleeve and a U-shaped plate-shaped chain collection bracket to replace the traditional handle structure. By fixing the crowbar sleeve to the chain collection bracket, not only the structure is simplified, but also the manufacturing is more convenient, thereby reducing the manufacturing cost of the product. When the present tensioner is in use, it is only necessary to insert the crowbar into the crowbar sleeve, and the tensioner can be pre-tightened by swinging the crowbar back and forth. At this time, since the crowbar can provide a longer lever length, the length of the chain collection bracket can be made smaller, so that the structural design of the tensioner can be made more compact, and the crowbar can be pulled out of the crowbar sleeve when not in use, so that the overall size of the product is smaller. In addition, one end of the crowbar sleeve faces the sprocket and the crowbar sleeve is perpendicular to the sprocket. This design allows the user to better control the applied force and direction, reducing the tilting or swaying of the crowbar sleeve caused by the force application process, and the force applied to the crowbar sleeve by the crowbar can be more effectively converted into the swing of the chain collection bracket without being wasted on movement in other directions. This direct torque transmission improves the efficiency of the operation, so that the user can more easily pre-tighten the tensioner through the crowbar, so the operation is more labor-saving and convenient, and can achieve a greater pre-tightening force, thereby improving the rated load of the tensioner, so that it can be better suitable for the fixation of heavy goods.

[0013] In the above-mentioned crowbar type chain tensioner, a support plate is fixedly connected inside the chain collection bracket, and one end of the crowbar sleeve facing the sprocket is abutted against the support plate and fixedly connected by welding.

[0014] During the use of the tensioner, the crowbar sleeve needs to withstand a large torque, so not only does the crowbar sleeve itself need not be deformed, but it also requires good connection stability. In view of this, the tensioner also fixes a connection support plate on the chain collection bracket, so that the end of the crowbar sleeve facing the sprocket is against the support plate, so that during the operation of the crowbar to swing repeatedly, the external force on the crowbar sleeve will be transmitted to the support plate, and then the crowbar sleeve is supported by the support plate, thereby further improving the connection stability of the crowbar sleeve, making the tensioner stable and reliable to use, and the tensioner can better use the crowbar to collect the chain, thereby achieving the purpose of labor-saving operation, and at the same time the tensioner can achieve a greater preload.

[0015] In the above-mentioned crowbar type chain tensioner, the crowbar sleeve is integrally formed with the chain collection bracket; or the crowbar sleeve is inserted into the chain collection bracket and is welded and fixedly connected to the chain collection bracket. Specifically, a mounting hole is provided at the closed end of the chain collection bracket, and the crowbar sleeve is inserted into the mounting hole and is welded and fixedly connected to the chain collection bracket, so that the crowbar sleeve and the chain collection bracket have good connection stability. With the abutment of the crowbar sleeve and the support plate, the connection stability of the crowbar sleeve is further strengthened, thereby improving the reliability and rated load of the tensioner, and the tensioner can achieve a greater preload force, thereby more stably fixing heavy goods.

[0016] In the above-mentioned crowbar type chain tensioner, the sprocket has a ratchet part, and a handle that can be embedded in the tooth groove of the ratchet part is slidably provided in the chain receiving bracket. The end of the handle facing away from the sprocket has a strip-shaped extension part, and a guide through hole is provided on the support plate, and the extension part is slidably inserted into the guide through hole. In this structure, the extension part is slidably inserted into the guide through hole, so that the support plate also plays a role in guiding the movement of the handle, thereby improving the movement stability of the handle during the use of the product. In other words, the support plate in the tensioner not only has a guiding function, but also plays a role in supporting the crowbar sleeve, achieving two uses of one thing. This can simplify the structure of the product, make the product structure compact, reduce the manufacturing cost, and is conducive to the miniaturized design of the product.

[0017] In the above-mentioned crowbar type chain tensioner, the cross section of the support plate is U-shaped, and the two ends of the support plate are respectively plugged and fixed on the two opposite side walls of the chain collection bracket, and the crowbar sleeve is vertically against the support plate. The cross section of the support plate is U-shaped, so that the support plate itself has good structural strength. At the same time, the two ends of the support plate are respectively plugged and fixed on the two opposite side walls of the chain collection bracket, ensuring good connection stability between the support plate and the chain collection bracket. Through such a design, the support plate can stably support the crowbar sleeve without being easily deformed, thereby improving the reliability and rated load of the tensioner, and the tensioner can achieve a greater preload force.

[0018] In the above-mentioned crowbar type chain tensioner, the handle includes two sliding parts arranged in parallel and capable of being embedded in the tooth grooves of the ratchet part, and a pulling part located between the two sliding parts and bent upward, and the two sliding parts are arranged on the two opposite side walls of the chain receiving bracket along the radial sliding direction of the sprocket. The two sliding parts are arranged on the two opposite side walls of the chain receiving bracket along the radial sliding direction of the sprocket, thereby guiding the movement of the handle and improving the movement stability of the handle during the use of the product. The setting of the pulling part can facilitate the user to pull the handle to move, thereby improving the convenience of product use.

[0019] In the above-mentioned crowbar type chain tensioner, the number of the extension parts on the handle is two, and the two extension parts are respectively located on both sides of the crowbar sleeve. The two extension parts are sleeved with a reset spring, and the two ends of the reset spring are respectively against the handle and the support plate. The two ends of the reset spring are respectively against the handle and the support plate, so that the handle has a tendency to be embedded in the tooth groove of the ratchet part, so that when the crowbar drives the chain collection bracket to swing, the handle can swing together and drive the sprocket to rotate, gradually tightening the chain on the sprocket. The provision of the two extension parts can further improve the stability of the handle movement process. At the same time, the two extension parts are respectively located on both sides of the crowbar sleeve, which can form a avoidance for the crowbar sleeve, thereby facilitating the provision of the crowbar sleeve at the closed end of the chain collection bracket, and making the product structure compact, thereby reducing the size of the product.

[0020] In the above-mentioned crowbar type chain tensioner, both ends of the support plate have plug-in protrusions, and the positions corresponding to each plug-in protrusion on the chain collection bracket are respectively provided with plug-in holes, and the plug-in protrusions of the support plate are plugged and fixed in the corresponding plug-in holes, and the plug-in protrusions are welded and fixedly connected to the plug-in holes or tightly fitted, and the two ends of the support plate are respectively abutted against and welded to the two side walls opposite to the chain collection bracket. Preferably, the plug-in protrusions are welded and fixedly connected to the plug-in holes, and the above-mentioned structure allows a larger welding area between the support plate and the chain collection bracket, thereby improving the connection stability of the support plate, so that the support plate can more stably support the crowbar sleeve, so that the connection stability of the crowbar sleeve is further strengthened, and the tensioner can better use the crowbar to perform chain collection operations.

[0021] In the above-mentioned crowbar type chain tensioner, the two sliding parts of the handle are integrally formed with protrusions, and the chain receiving bracket is provided with a strip-shaped guide sliding hole at a position corresponding to each protrusion, and the length direction of the guide sliding hole is arranged along the radial direction of the sprocket, and the protrusion is slidably arranged in the corresponding guide sliding hole. By sliding the protrusion in the corresponding guide sliding hole, the movement of the handle is guided, and the guiding effect is good, which can improve the movement stability of the handle during the use of the product.

[0022] Compared with the prior art, the crowbar type chain tensioner has the following advantages:

[0023] 1. The crowbar type chain tensioner adopts a crowbar sleeve and a U-shaped plate-shaped chain collection bracket to replace the traditional handle structure. By fixing the crowbar sleeve to the chain collection bracket, not only the structure is simplified, but also the manufacturing is more convenient, thereby reducing the manufacturing cost of the product.

[0024] 2. When the tensioner is in use, since the crowbar can provide a longer lever length, the length of the chain retracting bracket can be made smaller, so that the structural design of the tensioner can be more compact. When the crowbar is not in use, the crowbar is pulled out of the crowbar sleeve, making the overall size of the product smaller.

[0025] 3. When using this tensioner, the user can pre-tighten the tensioner more easily through a crowbar, so the operation is more labor-saving and convenient, and a greater pre-tightening force can be achieved, which increases the rated load of the tensioner, making it better suitable for fixing heavy goods. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a three-dimensional structural schematic diagram of the crowbar type chain tensioner.

[0027] Figure 2 It is a three-dimensional structural schematic diagram of the crowbar type chain tensioner after the chain is removed.

[0028] Figure 3 It is a cross-sectional view of the crowbar type chain tensioner.

[0029] Figure 4 It is a partial structural schematic diagram of the crowbar type chain tensioner.

[0030] Figure 5 It is a three-dimensional structural schematic diagram of the chain receiving bracket.

[0031] Figure 6 This is an exploded view of the handle and support plate.

[0032] Figure 7 It is a schematic diagram of the three-dimensional structure of the sprocket.

[0033] In the figure, 1. main bracket; 2. sprocket; 21. ratchet part; 22. axle; 3. chain receiving bracket; 31. side plate part; 311. plug-in hole; 312. guide sliding hole; 313. connecting hole; 32. connecting part; 321. mounting hole; 4. chain; 5. crowbar sleeve; 6. support plate; 61. guide through hole; 62. plug-in protrusion; 7. handle; 71. sliding part; 72. extension part; 73. pulling part; 74. protrusion; 8. reset spring. DETAILED DESCRIPTION

[0034] The following are specific embodiments of the present invention and the accompanying drawings to further describe the technical solution of the present invention, but the present invention is not limited to these embodiments.

[0035] Embodiment 1

[0036] like Figures 1 to 3 As shown, the crowbar type chain tensioner comprises a main bracket 1, a sprocket 2 connected to the main bracket 1, and a chain receiving bracket 3 which can drive the sprocket 2 to rotate when swinging, a chain 4 is wound around the sprocket 2, the chain receiving bracket 3 is in a U-shaped plate shape, and the open end of the chain receiving bracket 3 is rotatably connected to the sprocket 2, and a crowbar sleeve 5 is fixedly connected to the closed end of the chain receiving bracket 3, one end of the crowbar sleeve 5 faces the sprocket 2 and the crowbar sleeve 5 is perpendicular to the sprocket 2. At the same time, a support plate 6 is fixedly connected inside the chain receiving bracket 3, and the end of the crowbar sleeve 5 facing the sprocket 2 abuts against the support plate 6 and is welded and fixedly connected, so that in the process of operating the crowbar to swing repeatedly, the external force on the crowbar sleeve 5 will be transmitted to the support plate 6, and then the crowbar sleeve 5 is supported by the support plate 6, thereby further improving the connection stability of the crowbar sleeve 5, so that the tensioner is stable and reliable to use, and the tensioner can better use the crowbar to perform chain collection operation, thereby achieving the purpose of labor-saving operation, and the tensioner can achieve a greater preload force.

[0037] Specifically, Figure 3 and Figure 5 As shown, the chain collecting bracket 3 includes two side plate portions 31 arranged opposite to each other and a connecting portion 32 located between the two side plates, the two side plate portions 31 are parallel to each other, the connecting portion 32 and the side plate portions 31 are integrally formed and perpendicular to each other, the support plate 6 is located on the inner side of the connecting portion 32, the closed end of the chain collecting bracket 3 is the connecting portion 32, a mounting hole 321 is opened on the connecting portion 32, the crowbar sleeve 5 is passed through the mounting hole 321 and is welded and fixed to the chain collecting bracket 3, and the crowbar sleeve 5 is perpendicular to the connecting portion 32.

[0038] Combination Figure 1 , Figure 6 and Figure 7As shown, the sprocket 2 includes an axle 22, and the two ends of the sprocket 2 have ratchet parts 21 respectively. The ends of the two side plates 31 of the chain receiving bracket 3 are provided with connecting holes 313, and the two ends of the axle 22 are respectively rotatably penetrated in the connecting holes 313 of the two side plates 31, so that the chain receiving bracket 3 can rotate around the axle 22 of the sprocket 2. A handle 7 that can be embedded in the tooth groove of the ratchet part 21 is slidably provided on the chain receiving bracket 3, and the end of the handle 7 facing away from the sprocket 2 has two extension parts 72 that are both strip-shaped and parallel to each other. The cross section of the support plate 6 is U-shaped, and the two ends of the support plate 6 are respectively plugged and fixed on the two opposite side walls of the chain receiving bracket 3, and the crowbar sleeve 5 is vertically against the support plate 6. Two guide holes are provided on the support plate 6, and the two extension parts 72 are slidably penetrated in the two guide holes one by one. In this structure, the support plate 6 also plays a role in guiding the movement of the handle 7, thereby improving the movement stability of the handle 7 during the use of the product. That is to say, the support plate 6 in the tensioner not only has a guiding function, but also can support the crowbar sleeve 5, thus achieving dual purposes.

[0039] like Figures 4 to 6 As shown, both ends of the support plate 6 have a plug-in protrusion 62, and a plug-in hole 311 is respectively opened at a position corresponding to each plug-in protrusion 62 on the chain receiving bracket 3, and the plug-in protrusion 62 of the support plate 6 is plugged and fixed in the corresponding plug-in hole 311, and the plug-in protrusion 62 is welded and fixedly connected with the plug-in hole 311 or tightly fitted, and the two ends of the support plate 6 are respectively abutted against and welded and fixedly connected with the two side walls opposite to the chain receiving bracket 3. In this embodiment, the plug-in protrusion 62 is welded and fixedly connected with the plug-in hole 311, which makes a larger welding area between the support plate 6 and the chain receiving bracket 3, thereby improving the connection stability of the support plate 6, so that the support plate 6 can support the crowbar sleeve 5 more stably.

[0040] like Figure 6 As shown, the handle 7 includes two parallel sliding parts 71 that can be embedded in the tooth grooves of the ratchet part 21 and a pulling part 73 that is located between the two sliding parts 71 and bent upward. The two sliding parts 71 are both slidably arranged on the two opposite side walls of the chain receiving bracket 3 along the radial direction of the sprocket 2. Figure 3 and Figure 4 As shown, the two extensions 72 of the handle 7 are respectively located on both sides of the crowbar sleeve 5 , and the two extensions 72 are both sleeved with a return spring 8 , and the two ends of the return spring 8 are respectively against the handle 7 and the support plate 6 .

[0041] like Figures 4 to 6As shown, the two sliding parts 71 are integrally formed with protrusions 74, and the chain receiving bracket 3 is provided with strip-shaped guide holes at positions corresponding to each protrusion 74, and the length direction of the guide holes is arranged along the radial direction of the sprocket 2, and the protrusions 74 are slidably arranged in the corresponding guide holes. By sliding the protrusions 74 in the corresponding guide holes, the movement of the handle 7 is guided, and the guiding effect is good, which can improve the movement stability of the handle 7 during the use of the product.

[0042] When the tensioner is in use, it is only necessary to insert the crowbar into the crowbar sleeve 5, and the pre-tightening of the tensioner can be achieved by swinging the crowbar back and forth. At this time, since the crowbar can provide a longer lever length, the length dimension of the chain receiving bracket 3 can be made smaller, so that the structural design of the tensioner can be made more compact, and the crowbar is pulled out of the crowbar sleeve 5 when not in use, so that the overall size of the product is smaller. In addition, one end of the crowbar sleeve 5 faces the sprocket 2 and the crowbar sleeve 5 is perpendicular to the sprocket 2. Such a design allows the user to better control the applied force and direction, reduce the tilting or swinging of the crowbar sleeve 5 caused by the force application process, and the force applied by the crowbar to the crowbar sleeve 5 can be more effectively converted into the swing of the chain receiving bracket 3, and will not be wasted on the movement in other directions. This direct torque transmission improves the efficiency of the operation, so that the user can more easily achieve the pre-tightening of the tensioner through the crowbar, so the operation is also more labor-saving and convenient, and can achieve a larger pre-tightening force, improve the rated load of the tensioner, and thus can be better applied to the fixation of heavy goods.

[0043] Embodiment 2

[0044] The structure and principle of this embodiment are basically the same as those of the first embodiment, except that the crowbar sleeve 5 and the chain retracting bracket 3 are not fixedly connected by welding, but are integrally formed.

[0045] The specific embodiments described herein are merely examples of the spirit of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in similar ways, but they will not deviate from the spirit of the present invention or exceed the scope defined by the appended claims.

[0046] Although the following terms are used more frequently in this article: 1. main bracket; 2. sprocket; 21. ratchet portion; 22. axle; 3. chain receiving bracket; 31. side plate portion; 311. plug hole; 312. guide sliding hole; 313. connection hole; 32. connection portion; 321. mounting hole; 4. chain; 5. crowbar sleeve; 6. support plate; 61. guide through hole; 62. plug-in convex portion; 7. handle; 71. sliding portion; 72. extension portion; 73. pulling portion; 74. protrusion; 8. reset spring, the possibility of using other terms is not excluded. These terms are used only to more conveniently describe and explain the essence of the present invention; interpreting them as any additional limitation is contrary to the spirit of the present invention.

Claims

1. A crowbar type chain tensioner, comprising a main support (1), a sprocket (2) connected to the main support (1), and a chain receiving support (3) capable of driving the sprocket (2) to rotate when swinging, wherein a chain (4) is wound around the sprocket (2), characterized in that: The chain collecting bracket (3) is in the shape of a U-shaped plate, and the open end of the chain collecting bracket (3) is rotatably connected to the sprocket (2), and the closed end of the chain collecting bracket (3) is fixedly connected to a crowbar sleeve (5), one end of the crowbar sleeve (5) faces the sprocket (2), and the crowbar sleeve (5) is perpendicular to the sprocket (2).

2. The crowbar type chain tensioner according to claim 1, characterized in that: A support plate (6) is fixedly connected inside the chain collection bracket (3), and one end of the crowbar sleeve (5) facing the sprocket (2) abuts against the support plate (6) and is fixedly connected by welding.

3. The crowbar type chain tensioner according to claim 2, characterized in that: The crowbar sleeve (5) is integrally formed with the chain collection bracket (3); or the crowbar sleeve (5) is passed through the chain collection bracket (3) and is welded and fixedly connected to the chain collection bracket (3).

4. The crowbar type chain tensioner according to claim 2, characterized in that: The sprocket (2) has a ratchet portion (21), and a handle (7) capable of being embedded in a tooth groove of the ratchet portion (21) is slidably arranged in the chain receiving bracket (3), and the handle (7) has a strip-shaped extension portion (72) at one end facing away from the sprocket (2), and a guide through hole (61) is provided on the support plate (6), and the extension portion (72) is slidably penetrated into the guide through hole (61).

5. The crowbar type chain tensioner according to claim 2, 3 or 4, characterized in that: The cross section of the support plate (6) is U-shaped, and the two ends of the support plate (6) are respectively plugged and fixed on the two opposite side walls of the chain collection bracket (3), and the crowbar sleeve (5) is vertically pressed against the support plate (6).

6. The crowbar type chain tensioner according to claim 4, characterized in that: The handle (7) comprises two sliding parts (71) arranged in parallel and capable of being embedded in the tooth grooves of the part (21), and a pulling part (73) located between the two sliding parts (71) and bent upward, and the two sliding parts (71) are both arranged on two opposite side walls of the chain collection bracket (3) in a radially sliding manner along the sprocket (2).

7. The crowbar type chain tensioner according to claim 4, characterized in that: There are two extension parts (72) on the handle (7), and the two extension parts (72) are respectively located on both sides of the crowbar sleeve (5). The two extension parts (72) are both sleeved with a return spring (8), and the two ends of the return spring (8) are respectively against the handle (7) and the support plate (6).

8. The crowbar type chain tensioner according to claim 5, characterized in that: Both ends of the support plate (6) are provided with plug-in protrusions (62); positions on the chain receiving bracket (3) corresponding to each plug-in protrusion (62) are respectively provided with plug-in holes (311); and the plug-in protrusions (62) of the support plate (6) are plugged and fixed in corresponding plug-in holes (311).

9. The crowbar type chain tensioner according to claim 8, characterized in that: The plug-in protrusion (62) is welded and fixedly connected to the plug-in hole (311) or tightly fitted, and the two ends of the support plate (6) are respectively abutted against the two side walls opposite to the chain collection bracket (3) and are welded and fixedly connected.

10. The crowbar type chain tensioner according to claim 6, characterized in that: The two sliding parts (71) of the handle (7) are integrally formed with protrusions (74), and the chain receiving bracket (3) is provided with strip-shaped guide sliding holes (312) at positions corresponding to each protrusion (74), and the length direction of the guide sliding holes (312) is arranged along the radial direction of the sprocket (2), and the protrusions (74) are slidably arranged in the corresponding guide sliding holes (312).

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