Chain storage device

Abstract

The present invention provides a chain storage device, which relates to the technical field of chain storage. The chain storage device includes a chain storage barrel and a moving assembly. The chain storage barrel is provided with a chain storage chamber, and the upper end of the chain storage barrel is provided with an opening connected to the chain storage chamber. The moving assembly is provided in the chain storage chamber and is slidably connected to the chain storage barrel. The sliding direction of the moving assembly is inclined relative to the axial direction of the chain storage barrel, and the end of the moving assembly close to the opening is used to connect the chain. The chain storage device is used to recycle the chain into the chain storage chamber when the moving assembly slides to a position away from the opening. When the chain is moved out of the chain storage barrel, the moving assembly can move to a position close to the opening under the drive of the chain. When the chain is retracted into the chain storage barrel, the moving assembly moves to a position away from the opening under the action of gravity. At this time, the chain is retracted into the chain storage chamber and forms an approximately U-shaped chain storage shape in the chain storage chamber, thereby avoiding the phenomenon of chain accumulation and chain jamming after the chain is retracted into the chain storage chamber.

Description

Technical Field

[0001] The present invention relates to the technical field of chain storage, in particular to a chain storage device. Background Art

[0002] In a molten salt reactor system, when the reactor needs to be shut down urgently, control rods are typically extended into the reactor to control the reaction and avoid danger. When the control rods are raised and lowered using a sprocket-chain structure, the chain is typically stored in a chain storage drum. However, after being stored in the drum, the chains are prone to overlapping and accumulation, and when the chains are withdrawn again, they are prone to chain jamming. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a chain storage device in order to overcome the defects in the prior art that chains are easily accumulated and stuck in a chain storage barrel.

[0004] The present invention solves the above technical problems through the following technical solutions:

[0005] A chain storage device, comprising:

[0006] A chain storage cylinder, wherein the chain storage cylinder is provided with a chain storage chamber, and an upper end of the chain storage cylinder is provided with an opening communicating with the chain storage chamber;

[0007] a moving assembly disposed in the chain storage chamber, slidably connected to the chain storage barrel, wherein a sliding direction of the moving assembly is inclined relative to an axial direction of the chain storage barrel, and an end of the moving assembly close to the opening is used for connecting a chain;

[0008] The chain storage device is used for recovering the chain into the chain storage chamber when the moving assembly slides to a position away from the opening.

[0009] In this solution, the moving assembly is slidably connected to the chain storage barrel and is located in the chain storage chamber. Since one end of the chain is connected to the moving assembly, when the chain is moved out of the chain storage barrel, the moving assembly can move to a position close to the opening under the drive of the chain; when the chain is recovered into the chain storage barrel, the moving assembly moves to a position away from the opening under the action of gravity. At this time, the chain is recovered into the chain storage chamber and forms an approximately U-shaped chain storage shape in the chain storage chamber, thereby avoiding the phenomenon of chain accumulation and chain jamming after the chain is recovered into the chain storage chamber.

[0010] Preferably, a sliding groove is provided on the side wall of the chain storage barrel, and the sliding groove extends obliquely relative to the axial direction of the chain storage barrel;

[0011] The moving assembly is provided with a sliding member, and the moving assembly is slidably connected to the chain storage barrel through the cooperation between the sliding member and the sliding groove.

[0012] In this solution, the moving assembly is slidably connected to the chain storage barrel through the cooperation of the sliding member and the sliding groove. The sliding groove extends obliquely relative to the axial direction of the chain storage barrel, so that the sliding of the moving assembly in the chain storage chamber has both a vertical displacement component and a horizontal displacement component, thereby making sufficient storage space for the chain to be recovered into the chain storage barrel. In addition, the above-mentioned sliding connection structure is simple, which facilitates the assembly of the moving assembly and the chain storage barrel.

[0013] Preferably, the sliding groove is a smooth curved groove.

[0014] In this solution, the sliding groove is configured as a smooth curved groove, so that the sliding member can slide more smoothly along the sliding groove, thereby avoiding jamming during the sliding process.

[0015] Preferably, a plurality of the sliding grooves are respectively provided on two opposite sides of the chain storage barrel, and the plurality of sliding grooves are spaced apart along the axial direction of the chain storage barrel;

[0016] A plurality of sliding members are respectively provided on two opposite sides of the moving assembly, and the plurality of sliding members are arranged in a one-to-one correspondence with the plurality of sliding grooves.

[0017] In this solution, the sliding grooves are arranged on opposite sides of the chain storage barrel, and correspondingly, the sliding members are arranged on opposite sides of the moving assembly, which is conducive to ensuring the stability of the moving assembly in the horizontal direction during the sliding process; at the same time, multiple sliding grooves and multiple sliding members are arranged at intervals along the axial direction of the chain storage barrel, which is conducive to ensuring the stability of the moving assembly in the vertical direction during the sliding process, avoiding deviation and affecting the storage of the chain.

[0018] Preferably, the moving assembly includes a sleeve, a limiting member and a buffer member;

[0019] The limiting member is arranged in the sleeve, and one end of the limiting member close to the opening is used to connect with the chain;

[0020] The buffer is sleeved on the outer peripheral side of the limiter, and the two ends of the buffer respectively abut against the end of the sleeve close to the opening and the end of the limiter away from the opening. The buffer is used to apply a force to the limiter to move the limiter away from the opening.

[0021] In this solution, the sleeve has a certain protective effect on the limiter and buffer member inside it, and can also prevent the chain from contacting the buffer member and the like, so that the chain is accidentally stuck on the buffer member or the limiter; when the chain moves out of the chain storage barrel, the moving assembly moves to the end close to the opening of the chain storage barrel under the drive of the chain, and at this time the buffer member abutting between the sleeve and the limiter can cushion the movement of the limiter, thereby preventing a hard collision between the moving assembly and the chain storage barrel.

[0022] Preferably, the buffer member is composed of a plurality of disc springs stacked along the axial direction of the limiting member, the limiting member is a pull rod, and the plurality of disc springs are arranged on the outer circumference of the pull rod;

[0023] A pre-tightening nut is provided at one end of the pull rod away from the opening, and the plurality of disc springs are confined between the pre-tightening nut and one end of the sleeve close to the opening.

[0024] In this solution, the buffer component adopts a disc spring. The disc spring has the characteristics of high stiffness, strong buffering and vibration absorption ability, and can withstand large loads with small deformation. It can play a good buffering role in the impact between the moving component and the chain storage cylinder; the pull rod connects the disc springs in series, which can limit the disc springs. At the same time, the disc spring is limited between the pre-tightening nut and the end of the sleeve close to the opening, which can not only ensure the stability of the installation, but also give full play to the buffering performance of the disc spring.

[0025] Preferably, a section of the sleeve close to the opening is provided with an inclined surface and a connecting channel, and an end of the limiter close to the opening is provided with a first connecting hole, the first connecting hole is connected to the connecting channel, and the first connecting hole is used to connect the chain.

[0026] In this solution, the setting of the inclined surface can prevent the chain from piling up above the moving component when entering the chain storage chamber. The setting of the connecting channel facilitates the chain passing through it and connecting with the first connecting hole. The setting of the first connecting hole facilitates the connection of the chain to the moving component.

[0027] Preferably, the chain storage device further comprises a guide sleeve, wherein the guide sleeve is arranged at the opening of the chain storage cylinder, and the guide sleeve is provided with a guide channel, and the guide channel is communicated with the chain storage chamber.

[0028] In this solution, the provision of the guide sleeve facilitates the straightening of the chain when it is recovered into or removed from the chain storage barrel, and prevents the chain from being disordered and disoriented.

[0029] Preferably, the chain storage cylinder includes a surrounding plate, a baffle, a bottom plate and a connecting plate;

[0030] The enclosing plate and the baffle are both semi-enclosed structures, the enclosing plate and the baffle are arranged opposite to each other, and the enclosing plate, the baffle and the bottom plate are connected and together enclose the chain storage chamber;

[0031] The connecting plate is connected to the outer peripheral wall of the opening, and a plurality of second connecting holes are provided on the connecting plate.

[0032] In this solution, the enclosure and the baffle are both semi-enclosed structures, which are together arranged to form a cylindrical structure, which is easy to assemble. When the transmission components inside the chain storage barrel need to be repaired, the baffle can be easily removed for maintenance, which is conducive to improving maintenance efficiency; the setting of the bottom plate can prevent the chain from accidentally slipping out from the bottom of the chain storage barrel, thereby ensuring the safety of the chain storage; the setting of the connecting plate facilitates the installation of the chain storage barrel and ensures the firmness of the connection between the chain storage barrel and other components.

[0033] Preferably, the chain storage device further includes a driving member and a sprocket, wherein the sprocket is connected to the driving member and is located above the opening, and the driving member is used to drive the sprocket to rotate so as to lift and lower the chain.

[0034] In this solution, the driving member can provide power to the sprocket to drive the sprocket to rotate, and the sprocket further drives the chain located in the chain storage barrel to rise so as to pull the chain out of the chain storage barrel, or drives the chain located outside the chain storage barrel to descend and recycle the chain into the chain storage barrel; the sprocket is located above the opening of the chain storage barrel, which is convenient for raising and lowering the chain.

[0035] The positive progress effect of the present invention is:

[0036] In the present invention, the moving assembly is slidably connected to the chain storage barrel and is located in the chain storage chamber. Since one end of the chain is connected to the moving assembly, when the chain is moved out of the chain storage barrel, the moving assembly can be moved to a position close to the opening under the drive of the chain; when the chain is recovered into the chain storage barrel, the moving assembly moves to a position away from the opening under the action of gravity. At this time, the chain is recovered into the chain storage chamber and forms an approximately U-shaped chain storage shape in the chain storage chamber, thereby avoiding the phenomenon of chain accumulation and chain jamming after the chain is recovered into the chain storage chamber. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 1 is a perspective view of the three-dimensional structure of a chain storage device according to an embodiment of the present invention (the moving component is located in the first position).

[0038] Figure 2 1 is a perspective view of the three-dimensional structure of a chain storage device according to an embodiment of the present invention (the moving component is located in the second position).

[0039] Figure 3 Schematic diagram of the three-dimensional structure of a chain storage drum of a chain storage device according to an embodiment of the present invention.

[0040] Figure 4 FIG. 1 is a schematic diagram of the three-dimensional structure of a moving assembly of a chain storage device according to an embodiment of the present invention.

[0041] Figure 5 Schematic diagram of the three-dimensional structure of a guide sleeve of a chain storage device according to an embodiment of the present invention.

[0042] Figure 6 2 is a front structural schematic diagram of a guide sleeve of a chain storage device according to an embodiment of the present invention.

[0043] Figure 7 The figure is a schematic top view of the guide sleeve of the chain storage device according to one embodiment of the present invention.

[0044] Description of reference numerals:

[0045] Chain storage cylinder 1

[0046] Chain storage chamber 11

[0047] Opening 12

[0048] Slide slot 13

[0049] Hoarding 14

[0050] Baffle 15

[0051] Connecting plate 16

[0052] Second connecting hole 161

[0053] Mobile Component 2

[0054] Slider 21

[0055] Sleeve 22

[0056] Inclined surface 221

[0057] Connecting channel 222

[0058] Limiting piece 23

[0059] First connecting hole 231

[0060] Guide sleeve 3

[0061] Guide channel 31

[0062] Chain 4

[0063] Drive Component 5

[0064] Sprocket 6 DETAILED DESCRIPTION

[0065] The present invention will be described more clearly and completely below by way of embodiments in conjunction with the accompanying drawings, but the present invention is not limited to the scope of the embodiments.

[0066] like Figures 1 to 7As shown, this embodiment provides a chain storage device, which includes a chain storage barrel 1 and a moving assembly 2. The chain storage barrel 1 is provided with a chain storage chamber 11, and the upper end of the chain storage barrel 1 is provided with an opening 12 connected to the chain storage chamber 11; the moving assembly 2 is arranged in the chain storage chamber 11, and the moving assembly 2 is slidably connected to the chain storage barrel 1, and the sliding direction of the moving assembly 2 is inclined relative to the axial direction of the chain storage barrel 1, and the end of the moving assembly 2 close to the opening 12 is used to connect the chain 4; the chain storage device is used to recycle the chain 4 into the chain storage chamber 11 when the moving assembly 2 slides to a position away from the opening 12. The moving assembly 2 is slidably connected to the chain storage barrel 1 and is located in the chain storage chamber 11. Since one end of the chain 4 is connected to the moving assembly 2, when the chain 4 is moved out of the chain storage barrel 1, the moving assembly 2 can move to a position close to the opening 12 under the drive of the chain 4; when the chain 4 is recovered into the chain storage barrel 1, the moving assembly 2 moves to a position away from the opening 12 under the action of gravity. At this time, the chain 4 is recovered into the chain storage chamber 11 and forms an approximately U-shaped chain storage shape in the chain storage chamber 11, thereby avoiding the phenomenon of chain accumulation and chain jamming after the chain 4 is recovered into the chain storage chamber 11.

[0067] Specifically, in this embodiment, the moving assembly 2 can be in the first position (such as Figure 1 shown in the position relationship) and the second position (as shown in the position relationship) Figure 2 When the moving assembly 2 is in the first position, one end of the moving assembly 2 connected to the chain 4 is close to the opening 12, and the chain 4 moves out of the chain storage chamber 11. When the moving assembly 2 is in the second position, the chain 4 is retracted into the chain storage chamber 11, with one end of the chain 4 hooked to the upper end of the moving assembly 2 and the other end of the chain 4 hooked to the sprocket 6. The portion of the chain 4 located in the chain storage chamber 11 forms a U-shaped chain storage shape.

[0068] In this embodiment, the sidewall of the chain storage barrel 1 is provided with a sliding groove 13, which extends obliquely relative to the axial direction of the chain storage barrel 1. The movable assembly 2 is provided with a slider 21, which engages the sliding groove 13 to slidably connect the movable assembly 2 to the chain storage barrel 1. The engagement of the slider 21 with the sliding groove 13 slidably connects the movable assembly 2 to the chain storage barrel 1. The sliding groove 13 extends obliquely relative to the axial direction of the chain storage barrel 1, allowing the movable assembly 2 to slide within the chain storage chamber 11 with both vertical and horizontal displacement components. This creates sufficient storage space for the chain 4 to be retracted into the chain storage barrel 1. This sliding connection structure is simple, facilitating assembly of the movable assembly 2 and the chain storage barrel 1. Furthermore, the slider 21 slides within the sliding groove 13, simultaneously limiting the movement of the movable assembly 2 and ensuring its movement between the first and second positions.

[0069] In this embodiment, the sliding groove 13 is a smooth curved groove. This allows the sliding member 21 to slide along the sliding groove 13 more smoothly, avoiding any jamming during the sliding process. Specifically, in this embodiment, the sliding groove 13 is an arc-shaped groove, and the sliding member 21 is a rod-shaped member.

[0070] In this embodiment, a plurality of sliding grooves 13 are provided on opposite sides of the chain storage drum 1, spaced apart along the axial direction of the chain storage drum 1. A plurality of sliding members 21 are provided on opposite sides of the movable assembly 2, corresponding one-to-one with the plurality of sliding grooves 13. The provision of the sliding grooves 13 on opposite sides of the chain storage drum 1, and the corresponding provision of the sliding members 21 on opposite sides of the movable assembly 2, facilitates horizontal stability of the movable assembly 2 during sliding. Furthermore, the spaced apart axial direction of the plurality of sliding grooves 13 and the plurality of sliding members 21 on opposite sides of the chain storage drum 1 facilitates vertical stability of the movable assembly 2 during sliding, preventing deviation that could affect the storage of the chain 4.

[0071] Specifically, in this embodiment, the multiple sliding grooves 13 on both sides of the chain storage barrel 1 are evenly and symmetrically arranged, and the multiple sliding members 21 on both sides of the moving assembly 2 are evenly and symmetrically arranged, further increasing the sliding stability of the moving assembly 2.

[0072] In this embodiment, the moving component 2 includes a sleeve 22, a limit member 23 and a buffer member; the limit member 23 is arranged in the sleeve 22, and the end of the limit member 23 close to the opening 12 is used to connect the chain 4; the buffer member is sleeved on the outer peripheral side of the limit member 23, and the two ends of the buffer member respectively abut against the end of the sleeve 22 close to the opening 12 and the end of the limit member 23 away from the opening 12, and the buffer member is used to apply a force to the limit member 23 to make the limit member 23 away from the opening 12. The sleeve 22 has a certain protective effect on the limiter 23 and buffer member inside it, and can also prevent the chain 4 from contacting the buffer member and the like, so that the chain 4 is accidentally stuck on the buffer member or the limiter 23; when the chain 4 moves out of the chain storage drum 1, driven by the chain 4, the moving assembly 2 moves to the end close to the opening 12 of the chain storage drum 1, and at this time the buffer member abutting between the sleeve 22 and the limiter 23 can buffer the movement of the limiter 23, thereby preventing a hard collision between the moving assembly 2 and the chain storage drum 1.

[0073] In this embodiment, the buffer member comprises a plurality of disc springs stacked axially along a stopper 23, which is a pull rod. The multiple disc springs extend through the outer circumference of the pull rod. A preload nut is provided at the end of the pull rod away from the opening 12, and the multiple disc springs are restrained between the preload nut and the end of the sleeve 22 near the opening 12. The disc springs used in the buffer member have the characteristics of high rigidity, strong vibration damping and absorption, and the ability to withstand large loads with minimal deformation. They effectively buffer impacts between the moving assembly 2 and the chain storage drum 1. The pull rod connects the disc springs in series, limiting their position. Furthermore, the disc springs are restrained between the preload nut and the end of the sleeve 22 near the opening 12, ensuring both installation stability and fully utilizing the disc springs' cushioning properties.

[0074] In this embodiment, a section of the sleeve 22 near the opening 12 is provided with an inclined surface 221 and a connecting channel 222. A first connecting hole 231 is provided at the end of the retaining member 23 near the opening 12. The first connecting hole 231 communicates with the connecting channel 222 and is used to connect the chain 4. The inclined surface 221 prevents the chain 4 from accumulating above the moving assembly 2 when entering the chain storage chamber 11. The connecting channel 222 facilitates the chain 4's passage through it and connection with the first connecting hole 231. The first connecting hole 231 facilitates connection of the chain 4 to the moving assembly 2. Specifically, in this embodiment, the chain 4 is fixedly connected to the first connecting hole 231 of the retaining member 23 via a connecting pin.

[0075] In this embodiment, the chain storage device further includes a guide sleeve 3, which is disposed within the opening 12 of the chain storage drum 1. The guide sleeve 3 is provided with a guide channel 31, which communicates with the chain storage chamber 11. The provision of the guide sleeve 3 facilitates the smoothing of the chain 4 during its return to or removal from the chain storage drum 1, and prevents the chain 4 from becoming disorganized or disoriented. Specifically, in this embodiment, when the movable assembly 2 is in the first position, the movable assembly is located directly below the guide sleeve 3. When the movable assembly 2 slides from the first position to the second position, the movable assembly 2 slides away from directly below the guide sleeve 3, facilitating the chain 4's entry into the chain storage chamber 11 and preventing the chain 4 from stacking above the movable assembly 2.

[0076] In this embodiment, the chain storage drum 1 comprises a semi-enclosed structure, a baffle 15, a bottom plate, and a connecting plate 16. The enclosed plate 14 and baffle 15 are positioned opposite each other and connected to the bottom plate, collectively enclosing a chain storage chamber 11. The connecting plate 16 is connected to the outer peripheral wall of the opening 12 and is provided with a plurality of second connecting holes 161. The semi-enclosed structure of the enclosed plate 14 and baffle 15, collectively forming a cylindrical structure, facilitates assembly. When the transmission components within the chain storage drum 1 require maintenance, the baffle 15 can be easily removed for easy access, improving maintenance efficiency. The bottom plate prevents the chain 4 from accidentally slipping out from under the chain storage drum 1, ensuring chain storage safety. The connecting plate 16 facilitates installation of the chain storage drum 1 and ensures secure connections between the chain storage drum 1 and other components. Specifically, in this embodiment, the connecting plate 16 is used to securely connect the drive member 5.

[0077] In this embodiment, the chain storage device further includes a drive member 5 and a sprocket 6. The sprocket 6 is connected to the drive member 5 and is located above the opening 12. The drive member 5 is used to drive the sprocket 6 to rotate and raise and lower the chain 4. The drive member 5 can provide power to the sprocket 6 to drive the sprocket 6 to rotate. The sprocket 6 further drives the chain 4 located within the chain storage drum 1 to rise so that the chain 4 can be pulled out of the chain storage drum 1, or drives the chain 4 located outside the chain storage drum 1 to descend and retract the chain 4 into the chain storage drum 1. The sprocket 6 is located above the opening 12 of the chain storage drum 1, facilitating the raising and lowering of the chain 4.

[0078] When the chain storage device is used in a molten salt reactor system, one end of the chain 4 is connected to the moving assembly 2, and the other end is connected to the control rod. When the system is operating normally, the driver 5 drives the control rod up or down at a constant speed. When the system fails and the molten salt reactor reaction needs to be stopped urgently, the control rod, under the action of its own weight, quickly pulls the chain 4 out of the chain storage cylinder 1 and inserts it into the reactor to control the reaction.

[0079] Although specific embodiments of the present invention have been described above, those skilled in the art will appreciate that these are merely illustrative and that the scope of the present invention is defined by the appended claims. Those skilled in the art may make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, and such changes and modifications are intended to fall within the scope of the present invention.

Claims

1. A chain storage device, characterized in that: The chain storage device comprises: A chain storage cylinder, wherein the chain storage cylinder is provided with a chain storage chamber, and an upper end of the chain storage cylinder is provided with an opening communicating with the chain storage chamber; a moving assembly disposed in the chain storage chamber, slidably connected to the chain storage barrel, wherein a sliding direction of the moving assembly is inclined relative to an axial direction of the chain storage barrel, and an end of the moving assembly close to the opening is used for connecting a chain; The chain storage device is used to recycle the chain into the chain storage chamber when the moving assembly slides to a position away from the opening; The side wall of the chain storage barrel is provided with a sliding groove, and the sliding groove extends obliquely relative to the axial direction of the chain storage barrel; The moving assembly is provided with a sliding member, and the moving assembly is slidably connected to the chain storage barrel through the cooperation between the sliding member and the sliding groove; The moving assembly includes a sleeve, a limiting member and a buffer member; The limiting member is arranged in the sleeve, and one end of the limiting member close to the opening is used to connect with the chain; The buffer is sleeved on the outer peripheral side of the limiter, and the two ends of the buffer respectively abut against the end of the sleeve close to the opening and the end of the limiter away from the opening. The buffer is used to apply a force to the limiter to move the limiter away from the opening.

2. The chain storage device according to claim 1, characterized in that: The sliding groove is a smooth curved groove.

3. The chain storage device according to claim 1, characterized in that: A plurality of sliding grooves are respectively provided on opposite sides of the chain storage barrel, and the plurality of sliding grooves are spaced apart along the axial direction of the chain storage barrel; A plurality of sliding members are respectively provided on two opposite sides of the moving assembly, and the plurality of sliding members are arranged in a one-to-one correspondence with the plurality of sliding grooves.

4. The chain storage device according to claim 1, characterized in that: The buffer member is composed of a plurality of disc springs stacked along the axial direction of the limiter, the limiter is a pull rod, and the plurality of disc springs are arranged on the outer circumference of the pull rod; A pre-tightening nut is provided at one end of the pull rod away from the opening, and the plurality of disc springs are confined between the pre-tightening nut and one end of the sleeve close to the opening.

5. The chain storage device according to claim 1, characterized in that: The sleeve is provided with an inclined surface and a connecting channel at a section close to the opening, and the limiting member is provided with a first connecting hole at one end close to the opening. The first connecting hole is connected to the connecting channel and is used to connect the chain.

6. The chain storage device according to claim 1, characterized in that: The chain storage device further comprises a guide sleeve, which is arranged at the opening of the chain storage cylinder. The guide sleeve is provided with a guide channel, and the guide channel is communicated with the chain storage chamber.

7. The chain storage device according to claim 1, characterized in that: The chain storage cylinder includes a surrounding plate, a baffle, a bottom plate and a connecting plate; The enclosing plate and the baffle are both semi-enclosed structures, the enclosing plate and the baffle are arranged opposite to each other, and the enclosing plate, the baffle and the bottom plate are connected and together enclose the chain storage chamber; The connecting plate is connected to the outer peripheral wall of the opening, and a plurality of second connecting holes are provided on the connecting plate.

8. The chain storage device according to claim 1, characterized in that: The chain storage device further includes a driving member and a sprocket. The sprocket is connected to the driving member and is located above the opening. The driving member is used to drive the sprocket to rotate so as to lift and lower the chain.

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