An automatic processing equipment for outer sleeve of hydraulic cylinder

Abstract

The present invention discloses an automated processing equipment for the outer sleeve of a hydraulic cylinder, comprising a hollow base, a frame body fixedly installed on the top of the hollow base, a rotating shaft rotatably connected thereto is provided through the top of the hollow base, a placement plate is fixedly installed on one end of the rotating shaft outside the hollow base, a pinion is fixedly installed on one end of the rotating shaft inside the hollow base, a placement mechanism is provided above the placement plate, a rotation limiting mechanism is provided on the hollow base, and a clamping mechanism connected to the rotation limiting mechanism is provided on the hollow base. The present invention can successively complete the limiting of the outer cover retaining ring, the clamping assembly of the outer cover cylinder and the outer cover retaining ring, the rotation and spot welding of the assembly, the rotation and cooling of the assembly after spot welding, and the release of the limiting of the assembly in the process of rotating the connecting shaft one circle. The operation is simple and convenient, and the staff does not need to perform too much auxiliary operation, which improves the work efficiency and integrates assembly and spot welding.

Description

Technical Field

[0001] The invention relates to the technical field of hydraulic oil cylinders, and in particular to an automatic processing device for an outer sleeve of a hydraulic oil cylinder. Background Art

[0002] The outer sleeve of the hydraulic cylinder is an important part of the overall structure of the hydraulic cylinder. It not only prevents dust, dirt, rain, snow and acid erosion, but also supports the lifting weight of the hydraulic cylinder and reduces the impact of the overall weight of the dump truck compartment on the vehicle sub-beam.

[0003] When processing the outer sleeve of a small hydraulic cylinder, it is necessary to press and assemble the outer cover cylinder and the outer cover retaining ring. When using the existing equipment, many auxiliary operations are still required manually, such as auxiliary limiting and releasing of the outer cover retaining ring, auxiliary assembly of the outer cover cylinder and the outer cover retaining ring, etc. The degree of automation is low. At the same time, after the assembly is completed, additional equipment is currently required to spot weld it. Moreover, after spot welding, it is inconvenient for the staff to take it due to the high temperature of the assembly parts, which makes it inconvenient to use. Summary of the invention

[0004] The purpose of the present invention is to solve the shortcomings of the prior art and to propose an automatic processing equipment for the outer sleeve of a hydraulic cylinder.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A kind of automated processing equipment for the outer sleeve of a hydraulic cylinder comprises a hollow base, a frame is fixedly installed on the top of the hollow base, a rotating shaft rotatably connected to the top of the hollow base is penetrated, a placing plate is fixedly installed on the end of the rotating shaft located outside the hollow base, a pinion is fixedly installed on the end of the rotating shaft located inside the hollow base, a placing mechanism is arranged above the placing plate, a rotation limiting mechanism is arranged on the hollow base, a clamping mechanism connected to the rotation limiting mechanism is arranged on the hollow base, and a spot welding cooling mechanism connected to the rotation limiting mechanism is arranged on the hollow base.

[0007] Preferably, the placement mechanism includes two telescopic rods fixedly mounted on the inner walls on both sides of the frame, the telescopic ends of the two telescopic rods located on the inner wall on the same side of the frame are fixedly connected to the same placement block, and the four telescopic rods are all equipped with a first spring.

[0008] Preferably, the rotation limiting mechanism includes a motor fixedly mounted on the bottom inner side of the hollow base, the output shaft of the motor is fixedly connected to the connecting shaft, a large gear is fixedly mounted on the outer side wall of the connecting shaft, a cam is fixedly mounted on the top of the connecting shaft, a fixing cylinder fixedly connected to it is penetrated through the inner wall of one side of the hollow base, a long rod slidably connected to it is penetrated through the end of the fixing cylinder close to the cam, a first protrusion abutting against the cam is fixedly mounted on the end of the long rod located outside the fixing cylinder, a first plug body slidably connected to its inner wall is fixedly mounted on the end of the long rod located inside the fixing cylinder, a tension spring is fixedly connected between the first plug body and the inner wall of one end of the fixing cylinder close to the cam, a conductive ring between the first plug body and the first protrusion is provided on the inner wall of the fixing cylinder, and a third conductive block is provided on the side wall of the first plug body close to the conductive ring.

[0009] Preferably, two symmetrically arranged fixing plates are fixedly installed on the top of the placing plate, a first cylinder is fixedly installed on one side wall of the two fixing plates close to each other, a clip is fixedly installed on the telescopic end of the two first cylinders, and the conductive ring and the third conductive block are both located in the circuit of the two first cylinders.

[0010] Preferably, the clamping mechanism includes a box body fixedly mounted on the inner wall of one end of the hollow base, a pressure rod slidably connected to the cam is penetrated through one side wall of the box body close to the cam, a second protrusion that abuts against the cam is fixedly mounted on the end of the pressure rod outside the box body, a second spring is fixedly connected between the second protrusion and the box body, and a pressure plate slidably connected to the inner wall of the box body is fixedly mounted on the end of the pressure rod located inside the box body.

[0011] Preferably, a pressure cylinder is fixedly installed on the inner bottom of the frame, a second plug body slidably connected to the inner wall of the pressure cylinder is arranged inside the pressure cylinder, a connecting rod is fixedly connected to the bottom of the second plug body, a pressure block located outside the pressure cylinder is fixedly installed on the bottom of the connecting rod, a first connecting tube connected to the interior of the box body is provided on the box body, an end of the first connecting tube connected to the box body is located on the side of the pressure block away from the pressure rod, an end of the first connecting tube away from the box body is connected to the pressure cylinder, and an end of the first connecting tube connected to the pressure cylinder is located above the second plug body.

[0012] Preferably, the spot welding cooling mechanism includes a second cylinder fixedly mounted on an inner wall on one side of a frame body, a welding gun located between a placement block and a placement plate is arranged on the telescopic end of the second cylinder, a box body located between the placement plate and the placement block is arranged in the frame body, a second connecting pipe and a third connecting pipe connected to the interior of the fixed cylinder are arranged on the fixed cylinder, one end of the second connecting pipe and the third connecting pipe connected to the fixed cylinder are both located on the side of the first plug body away from the long rod, a one-way valve is arranged in the second connecting pipe and the third connecting pipe, one end of the second connecting pipe away from the fixed cylinder is connected to the box body, a first conductive sheet is arranged on the inner top of the hollow base, a second conductive sheet is arranged on the top of the cam, and the first conductive sheet and the second conductive sheet are both located in the circuit of the second cylinder.

[0013] Preferably, a placement groove is provided on one side of the two placement blocks close to each other, and a part of teeth is provided on the large gear.

[0014] Beneficial effects of the present invention:

[0015] By setting up a placement mechanism, the outer cover cylinder to be assembled can be placed in the area surrounded by two placement blocks to achieve support for the outer cover cylinder. At the same time, in the subsequent assembly process, the outer cover cylinder can be straightened to avoid deviation of the outer cover cylinder and ensure the accuracy of assembly.

[0016] By setting a clamping mechanism and a rotation limiting mechanism, the outer cover retaining ring can be limited and the outer cover cylinder and the outer cover retaining ring can be assembled in succession during the process of the connecting shaft rotating one circle. The operation is simple and convenient, and the staff only needs to place the outer cover cylinder and the outer cover retaining ring.

[0017] By setting up a spot welding cooling mechanism, the welding gun can be brought close to the rotating assembly to achieve spot welding of the outer cover cylinder and the outer cover retaining ring during the process of the connecting shaft rotating one circle. At the same time, after spot welding, the assembly that has completed spot welding can be automatically blown to accelerate cooling and finally release the limit of the assembly.

[0018] The present invention can successively complete the limiting of the outer cover retaining ring, the compression assembly of the outer cover cylinder and the outer cover retaining ring, the rotation and spot welding of the assembly part, the rotation and cooling of the assembly part after spot welding, and finally the release of the limiting of the assembly part during the process of the connecting shaft rotating one circle. The operation is simple and convenient, and the staff does not need to perform too much auxiliary operation, which improves the work efficiency and integrates assembly and spot welding. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a three-dimensional structural schematic diagram of one side of an automatic processing device for the outer sleeve of a hydraulic cylinder proposed by the present invention;

[0020] Figure 2This is a schematic diagram of the three-dimensional structure of the other side of the automatic processing equipment for the outer sleeve of a hydraulic cylinder proposed by the present invention;

[0021] Figure 3 It is a schematic diagram of the three-dimensional structure in the hollow base of the present invention;

[0022] Figure 4 It is a schematic diagram of the planar structure inside the hollow base of the present invention;

[0023] Figure 5 It is a schematic diagram of the planar structure inside the pressing cylinder of the present invention.

[0024] In the figure: 1 frame, 2 pressure block, 3 pressure cylinder, 4 first connecting pipe, 5 placement block, 6 first spring, 7 telescopic rod, 8 box body, 9 second connecting pipe, 10 fixed cylinder, 11 third connecting pipe, 12 placement plate, 13 clamp, 14 first cylinder, 15 welding gun, 16 hollow base, 17 second cylinder, 18 fixed block, 19 box body, 20 pressure rod, 21 large gear, 22 small gear, 23 rotating shaft, 24 first conductive sheet, 25 cam, 26 second conductive sheet, 27 first protrusion, 28 motor, 29 connecting shaft, 30 second protrusion, 31 second spring, 32 pressure plate, 33 conductive ring, 34 third conductive sheet, 35 first plug body, 36 long rod, 37 tension spring, 38 second plug body, 39 connecting rod, 40 placement groove. DETAILED DESCRIPTION

[0025] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0026] Reference Figure 1-Figure 5 , an automatic processing equipment for the outer sleeve of a hydraulic cylinder, comprising a hollow base 16, a frame 1 is fixedly installed on the top of the hollow base 16, a rotating shaft 23 rotatably connected to the hollow base 16 is provided through the top of the hollow base 16, a placing plate 12 is fixedly installed on one end of the rotating shaft 23 located outside the hollow base 16, a pinion 22 is fixedly installed on one end of the rotating shaft 23 located inside the hollow base 16, a placing mechanism is provided above the placing plate 12, the placing mechanism comprises two telescopic rods 7 fixedly installed on the inner walls on both sides of the frame 1, the telescopic ends of the two telescopic rods 7 located on the inner wall on the same side of the frame 1 are fixedly connected to the same placing block 5, and the four telescopic rods 7 are all provided with a first spring 6;

[0027] A rotation limiting mechanism is provided on the hollow base 16, and the rotation limiting mechanism includes a motor 28 fixedly installed on the inner bottom of the hollow base 16, the output shaft of the motor 28 is fixedly connected to the connecting shaft 29, the outer wall of the connecting shaft 29 is fixedly installed with a large gear 21, and the top of the connecting shaft 29 is fixedly installed with a cam 25. A fixed cylinder 10 fixedly connected to it is penetrated through the inner wall of one side of the hollow base 16, and a long rod 36 slidably connected to it is penetrated through the end of the fixed cylinder 10 close to the cam 25, and a first protrusion 27 that abuts against the cam 25 is fixedly installed on the end of the long rod 36 located outside the fixed cylinder 10, and a first plug body 35 slidably connected to its inner wall is fixedly installed on the end of the long rod 36 located in the fixed cylinder 10. A tension spring 37 is fixedly connected between the body 35 and the inner wall of one end of the fixed cylinder 10 close to the cam 25, a conductive ring 33 is arranged between the first plug body 35 and the first protrusion 27 on the inner wall of the fixed cylinder 10, a third conductive block 34 is arranged on a side wall of the first plug body 35 close to the conductive ring 33, two symmetrically arranged fixed plates 18 are fixedly installed on the top of the placement plate 12, the first cylinder 14 is fixedly installed on the side wall of the two fixed plates 18 close to each other, the clip 13 is fixedly installed on the telescopic end of the two first cylinders 14, the conductive ring 33 and the third conductive block 34 are both located in the circuit of the two first cylinders 14, a placement groove 40 is opened on the side of the two placement blocks 5 close to each other, and some teeth are arranged on the large gear 21;

[0028] The hollow base 16 is provided with a clamping mechanism connected with the rotation limiting mechanism, and the clamping mechanism includes a box body 19 fixedly mounted on the inner wall at one end of the hollow base 16, and a pressure rod 20 slidably connected with the cam 25 is provided on one side wall of the box body 19 close to the cam 25, and a second protrusion 30 abutting against the cam 25 is fixedly mounted on the end of the pressure rod 20 located outside the box body 19, and a second spring 31 is fixedly connected between the second protrusion 30 and the box body 19, and a pressure plate 32 slidably connected with the inner wall of the box body 19 is fixedly mounted on the end of the pressure rod 20 located inside the box body 19. A pressing cylinder 3 is fixedly installed at the inner bottom of the body 1, and a second plug body 38 is provided in the pressing cylinder 3 and is slidably connected to the inner wall thereof. A connecting rod 39 is fixedly connected to the bottom of the second plug body 38, and a pressing block 2 located outside the pressing cylinder is fixedly installed at the bottom of the connecting rod 39. A first connecting pipe 4 connected to the interior of the box body 19 is provided on the box body 19, and one end of the first connecting pipe 4 connected to the box body 19 is located on the side of the pressing plate 32 away from the pressing rod 20, and one end of the first connecting pipe 4 away from the box body 19 is connected to the pressing cylinder 3, and one end of the first connecting pipe 4 connected to the pressing cylinder 3 is located above the second plug body 38;

[0029] A spot welding cooling mechanism connected to the rotation limiting mechanism is arranged on the hollow base 16, and the spot welding cooling mechanism includes a second cylinder 17 fixedly mounted on the inner wall of one side of the frame body 1, and a welding gun 15 located between the placement block 5 and the placement plate 12 is arranged on the telescopic end of the second cylinder 17, and a box body 8 located between the placement plate 12 and the placement block 5 is arranged in the frame body 1, and a second connecting pipe 9 and a third connecting pipe 11 connected to the interior of the fixed cylinder 10 are arranged on the fixed cylinder 10, and the ends of the second connecting pipe 9 and the third connecting pipe 11 connected to the fixed cylinder 10 are both located on the side of the first plug body 35 away from the long rod 36, and a one-way valve is arranged in the second connecting pipe 9 and the third connecting pipe 11, and the end of the second connecting pipe 9 away from the fixed cylinder 10 is connected to the box body 8, a first conductive sheet 24 is arranged on the inner top of the hollow base 16, and a second conductive sheet 26 is arranged on the top of the cam 25, and the first conductive sheet 24 and the second conductive sheet 26 are both located in the circuit of the second cylinder 17.

[0030] When the present invention is used, a certain size of the outer cover cylinder is placed in the area surrounded by the two placement grooves 40, and the outer cover retaining ring is placed between the two clips 13 on the placement plate 12. The initial state of the cam 25 is as shown in the attached figure. Figure 4 As shown, at this time, the tension spring 37 is in a stretched state, and the connecting shaft 29, the large gear 21 and the cam 25 are rotated counterclockwise by starting the motor 28. During the first counterclockwise rotation of the cam 25 by 90 degrees, the tension generated by the stretched tension spring 37 can make the first plug body 35 move in the direction close to the connecting shaft 29, and the external air is sucked into the fixed cylinder 20 through the third connecting pipe 11. The movement of the first plug body 35 drives the movement of the third conductive sheet 34, so that the third conductive sheet 34 and the conductive ring 33 contact each other, and the circuits of the two first cylinders 14 are connected so that the two clamping sheets 13 are close to each other to clamp and fix the outer cover retaining ring and make it located directly below the pressing block 2;

[0031] During the first counterclockwise rotation of the cam 25 and the large gear 21 by 90 degrees, the cam 25 also causes the second protrusion 30, the pressure rod 20 and the pressure plate 32 to move in the direction away from the connecting shaft 29, the second spring 31 is compressed, and the pressure plate 32 moves so that the filling oil in the box body 19 is squeezed into the pressure cylinder 3 through the first connecting pipe 4, thereby causing the second plug body 38 to move downward. The pressure block 2 is moved downward by setting the connecting rod 39. Since the internal length of the box body 19 is large and the internal diameter of the pressure cylinder 3 is small, the pressure block 2 can move downward for a long distance. During the downward movement of the pressure block 2, it will contact with the outer cover cylinder and cause the outer cover cylinder to move downward. The outer cover cylinder will cause the two placement blocks 5 to move away from each other, and the telescopic rod 7 will retract. The first spring 36 is compressed. The elastic force generated by the compression of the first spring 36 can ensure that the outer cover cylinder moves vertically downward without deviation, and is positioned. The outer cover cylinder moving downward will eventually pass between the two placement blocks 5 and be pressed into the clamped outer cover retaining ring to complete the press fitting.

[0032] Then, the cam 25 and the large gear 21 rotate counterclockwise by 90 degrees for the second time, and the third conductive sheet 34 and the conductive ring 33 are still in contact with each other. The elastic force generated by the compression of the second spring 31 can reset the pressure plate 32, and then the second plug body 38, the connecting rod 39 and the pressure block 2 move upward to return to the initial position for the next press-fitting. At the same time, when the cam 25 and the large gear 21 rotate counterclockwise by 90 degrees for the second time, the second conductive sheet 26 on the cam 25 and the first conductive sheet 24 contact each other, so that the second cylinder 17 is connected to the circuit and the welding gun 15 is close to the assembled outer cover cylinder. During the third counterclockwise rotation of the cam 25 and the large gear 21 by 90 degrees, part of the teeth on the large gear 21 mesh with the pinion 22, and the pinion 22, the rotating shaft 23, the placement plate 12 and the assembled outer cover cylinder and the outer cover retaining ring rotate one circle, and the welding gun 15 that is close can spot weld the gap between the outer cover cylinder and the outer cover retaining ring.

[0033] When the cam 25 and the large gear 21 rotate counterclockwise for the fourth time by 90 degrees and return to the initial position, the second conductive sheet 26 on the cam 25 and the first conductive sheet 24 are no longer in contact with each other, and the welding gun 15 moves away from the outer cover cylinder and returns to the initial position. The rotating cam 25 causes the first plug 35 to move away from the connecting shaft 35, so that the air sucked into the fixed cylinder 10 is squeezed into the box body 8 through the second connecting pipe 9 and sprayed out to the outer cover cylinder and the outer cover retaining ring after spot welding, so as to cool them down. During the rotation of the large gear 21, some teeth on the large gear 21 are The teeth and the pinion 22 first mesh with each other and then separate and no longer mesh, so that the assembled outer cover cylinder and the outer cover retaining ring rotate one circle again, that is, the outer cover cylinder and the outer cover retaining ring also rotate one circle while the box body 8 sprays gas, so as to evenly cool down. When the first plug 35 moves away from the connecting shaft 35 and returns to the initial position, the third conductive sheet 34 and the conductive ring 33 change from being in contact with each other to being no longer in contact, that is, the two clamps 13 move away from each other so that the outer cover retaining ring is no longer clamped and fixed, so that the outer cover cylinder and the outer cover retaining ring after spot welding can be removed.

[0034] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. An automated processing device for the outer sleeve of a hydraulic cylinder, comprising a hollow base (16), characterized in that: A frame body (1) is fixedly mounted on the top of the hollow base (16); a rotating shaft (23) rotatably connected to the frame body (16) is provided through the top of the hollow base (16); a placement plate (12) is fixedly mounted on one end of the rotating shaft (23) located outside the hollow base (16); a pinion (22) is fixedly mounted on one end of the rotating shaft (23) located inside the hollow base (16); a placement mechanism is provided above the placement plate (12); the placement mechanism comprises two telescopic rods (7) fixedly mounted on the inner walls of both sides of the frame body (1); the telescopic ends of the two telescopic rods (7) located on the inner wall of the same side of the frame body (1) are fixedly connected to the same placement block (5); the four telescopic rods (7) are all provided with a first spring (6); and a rotation limiting mechanism is provided on the hollow base (16). The rotation limiting mechanism comprises a motor (28) fixedly mounted on the bottom of the hollow base (16), the output shaft of the motor (28) is fixedly connected to a connecting shaft (29), a large gear (21) is fixedly mounted on the outer wall of the connecting shaft (29), a cam (25) is fixedly mounted on the top of the connecting shaft (29), a fixed cylinder (10) fixedly connected to the inner wall of one side of the hollow base (16) is penetrated, an end of the fixed cylinder (10) close to the cam (25) is penetrated and a long rod (36) is slidably connected to the cam (25), an end of the long rod (36) located outside the fixed cylinder (10) is fixedly mounted with a first protrusion (27) abutting against the cam (25), and an end of the long rod (36) located inside the fixed cylinder (10) is fixedly mounted with a first protrusion (27) slidably connected to the inner wall A first plug body (35) is movably connected, a tension spring (37) is fixedly connected between the first plug body (35) and the inner wall of one end of the fixed cylinder (10) close to the cam (25), a clamping mechanism connected to the rotation limit mechanism is arranged on the hollow base (16), the clamping mechanism comprises a box body (19) fixedly mounted on the inner wall of one end of the hollow base (16), a pressure rod (20) slidably connected to the box body (19) is penetrated through a side wall of the box body (19) close to the cam (25), a second convex block (30) abutting against the cam (25) is fixedly mounted on one end of the pressure rod (20) located outside the box body (19), a second spring (31) is fixedly connected between the second convex block (30) and the box body (19), and one end of the pressure rod (20) located inside the box body (19) is fixedly mounted. A pressure plate (32) is installed which is slidably connected to the inner wall of the box body (19); a pressure cylinder (3) is fixedly installed on the inner bottom of the frame body (1); a second plug body (38) which is slidably connected to the inner wall of the pressure cylinder (3) is arranged in the pressure cylinder (3); a connecting rod (39) is fixedly connected to the bottom of the second plug body (38); a pressure block (2) located outside the pressure cylinder is fixedly installed on the bottom of the connecting rod (39); a first connecting pipe (4) which is connected to the interior of the box body (19); an end of the first connecting pipe (4) which is connected to the box body (19) is located on a side of the pressure plate (32) away from the pressure rod (20); an end of the first connecting pipe (4) which is away from the box body (19) is connected to the pressure cylinder (3); an end of the first connecting pipe (4) which is connected to the pressure cylinder (3) is located above the second plug body (38);A spot welding cooling mechanism connected to the rotation limiting mechanism is provided on the hollow base (16).

2. According to claim 1, an automatic processing equipment for outer sleeve of hydraulic cylinder, characterized in that: A conductive ring (33) is provided on the inner wall of the fixed cylinder (10) between the first plug body (35) and the first protrusion (27); a third conductive block (34) is provided on a side wall of the first plug body (35) close to the conductive ring (33); two symmetrically arranged fixed plates (18) are fixedly mounted on the top of the placement plate (12); first cylinders (14) are fixedly mounted on side walls of the two fixed plates (18) close to each other; clips (13) are fixedly mounted on telescopic ends of the two first cylinders (14); and the conductive ring (33) and the third conductive block (34) are both located in the circuits of the two first cylinders (14).

3. An automatic processing equipment for outer sleeve of hydraulic cylinder according to claim 2, characterized in that: The spot welding cooling mechanism comprises a second cylinder (17) fixedly mounted on an inner wall of one side of a frame (1); a welding gun (15) located between a placement block (5) and a placement plate (12) is arranged on a telescopic end of the second cylinder (17); a box body (8) located between the placement plate (12) and the placement block (5) is arranged in the frame (1); a second connecting pipe (9) and a third connecting pipe (11) connected to the interior of the fixed cylinder (10) are arranged on the fixed cylinder (10); the second connecting pipe (9) and the third connecting pipe (11) are connected to the fixed cylinder (10); The first and second connecting tubes (10) are connected to the first plug body (35) at one end thereof which is away from the long rod (36). The second connecting tube (9) and the third connecting tube (11) are both provided with a one-way valve. The end of the second connecting tube (9) which is away from the fixed tube (10) is connected to the box body (8). The top of the hollow base (16) is provided with a first conductive sheet (24). The top of the cam (25) is provided with a second conductive sheet (26). The first conductive sheet (24) and the second conductive sheet (26) are both located in the circuit of the second cylinder (17).

4. An automatic processing equipment for outer sleeve of hydraulic cylinder according to claim 3, characterized in that: A placement groove (40) is provided on one side of the two placement blocks (5) that are close to each other, and a portion of teeth are provided on the large gear (21).

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