Machining and positioning tool for hydraulic cylinder barrel of agricultural machine
By designing, adjusting, and installing components to drive the coordination of the arc-shaped clamping plate and the movable clamping arc plate, the problem of insufficient clamping force in the traditional hydraulic cylinder positioning fixture for agricultural machinery is solved, achieving stable fixing of the cylinder and improving processing quality, making it suitable for large-scale industrial production.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-01
- Publication Date
- 2026-03-27
AI Technical Summary
Traditional agricultural machinery hydraulic cylinder positioning fixtures suffer from insufficient pneumatic clamping force during processing, leading to workpiece vibration, unstable surface quality, and unsuitability for large-scale industrial production.
A positioning fixture for machining the cylinder barrel of an agricultural machinery hydraulic cylinder, including an adjustment component and an installation component, was designed. By utilizing the cooperation of an arc-shaped clamping plate and a movable clamping arc plate, the cylinder barrel is stably fixed by a motor drive. The adjustment motor and the installation motor control the rotation of the adjustment double-screw and the installation rod, respectively, to ensure the stability of the cylinder barrel during the machining process.
It achieves stable fixing of the hydraulic cylinder barrel of agricultural machinery, reduces shaking during processing, improves processing quality and application range, and is suitable for large-scale industrial production.
Smart Images

Figure CN224043159U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The utility model relates to agricultural machinery hydraulic cylinder processing technical field especially relates to a kind of agricultural machinery hydraulic cylinder cylinder barrel processing positioning tool. BACKGROUND
[0002] Agricultural machinery hydraulic cylinder cylinder barrel is the core component of hydraulic cylinder, mainly by cylinder body, piston, piston rod and sealing element etc., cylinder barrel is the main body of hydraulic cylinder, inner hole usually adopts boring, reaming, rolling or honing etc. Precise machining process, to withstand high hydraulic pressure, and ensure enough strength and stiffness, while in cylinder barrel production needs to be positioned after processing by positioning tool, traditional positioning tool is tightly processed to cylinder barrel material, since adopting pneumatic pressing mode, there can be not enough pressing force, workpiece is easily vibrated in processing, leading to workpiece surface quality easily appears the situation of over-difference, and whether workpiece has been pressed is confirmed, while processing process also needs manual operation pressing mechanism, not conducive to large-scale industrial production, thereby reducing use effect. SUMMARY
[0003] The utility model aims at solving the shortcoming that the stability effect of the existing agricultural machinery hydraulic cylinder cylinder barrel is poor, and provides an agricultural machinery hydraulic cylinder cylinder barrel processing positioning tool.
[0004] In order to achieve the above object, the utility model adopts the following technical scheme: two symmetrical assembly grooves are arranged on the assembly tool table, any assembly groove penetrates the assembly tool table along the thickness direction of the assembly tool table, an assembly sliding block is slidably connected in the assembly sliding groove, an assembly hollow plate and an assembly sleeve block are fixedly connected at the both ends of the assembly sliding block, an assembly lug is fixedly connected on the side wall of the assembly sleeve block, an assembly support plate is rotatably connected with the assembly lug, an adjusting assembly is connected with the assembly support plate and connected at the bottom of the assembly tool table.
[0005] A fixed extension tooth plate is slidably connected in the assembly hollow plate, a fixed motor is connected at one end of the fixed extension tooth plate, an installation arc abutting plate is connected with the output shaft of the fixed motor, a fixed space is formed between the two arc abutting plates, movable abutting arc plates are connected at the both sides of the installation arc abutting plate, and the movable abutting arc plates can move close to / distance from the fixed space.
[0006] Further description of the above technical scheme:
[0007] The adjusting assembly includes two adjusting blocks fixedly connected with the bottom of the assembly tool table, a guide rod is fixedly connected between the two adjusting blocks, two adjusting sleeve blocks are movably sleeved on the outer side wall of the guide rod, and the assembly support plate is rotatably connected with the adjusting sleeve blocks.
[0008] As a further description of the above technical solutions:
[0009] Both ends of the adjusting sleeve block are fixedly connected with adjusting supporting lugs, the adjusting supporting lugs are rotationally connected with the corresponding assembly supporting plates, and one surface of the adjusting block is fixedly connected with an adjusting motor.
[0010] As a further description of the above technical solutions:
[0011] The output end of the adjusting motor is fixedly connected with an adjusting bidirectional screw rod, the distal end of the adjusting bidirectional screw rod penetrates one adjusting block and is rotationally connected with the other adjusting block, and both the adjusting sleeve blocks are threadedly connected with the outer side wall of the adjusting bidirectional screw rod to relatively move close to or away from each other.
[0012] As a further description of the above technical solutions:
[0013] The assembly supporting plates are rotationally connected with the assembly hollow plates through assembly rotating shafts, and the adjusting supporting lugs are rotationally connected with the corresponding assembly supporting plates through adjusting rotating shafts.
[0014] As a further description of the above technical solutions:
[0015] The assembly hollow plate side wall is connected with an installation assembly for adjusting the movement of the fixed extension toothed plate, the assembly hollow plate side wall is provided with an installation slot, at least part of the installation assembly penetrates into the assembly hollow plate through the installation slot, and is connected with the fixed extension toothed plate.
[0016] As a further description of the above technical solutions:
[0017] The installation assembly comprises two installation supporting frames fixedly connected with the assembly hollow plate side wall, one surface of one installation supporting frame is fixedly connected with an installation motor, the output end of the installation motor is fixedly connected with an installation rod, the distal end of the installation rod penetrates one installation supporting frame and is rotationally connected with the other installation supporting frame, the outer side wall of the installation rod is sleeved with an installation gear, the installation gear penetrates into the assembly hollow plate through the installation slot, and is meshingly connected with the fixed extension toothed plate.
[0018] As a further description of the above technical solutions:
[0019] One end of the fixed extension toothed plate is fixedly connected with a fixed baffle, the side wall of the fixed baffle is fixedly connected with a fixed motor, and the output shaft of the fixed motor penetrates the fixed baffle and is fixedly connected with an installation arc-shaped abutting plate.
[0020] As a further description of the above technical solutions:
[0021] The mounting arc-shaped abutting plate is connected to the movable abutting arc plate through the movable assembly, and the movable assembly comprises a first movable gear and a second movable gear which are engaged with each other, the second movable gear is arranged on the movable abutting arc plate, and the second movable gear is arranged on the arc-shaped abutting plate.
[0022] As a further description of the above technical solution:
[0023] The movable assembly comprises a movable recess block fixedly connected to the surface of the mounting arc-shaped abutting plate, the movable recess block is rotationally connected with a movable rotating shaft, an outer side wall of the movable rotating shaft is fixedly sleeved with the movable abutting arc plate, and one end of the movable rotating shaft penetrates through the movable recess block and is fixedly connected with the first movable gear.
[0024] The utility model has the advantages of the following beneficial effects:
[0025] The arc-shaped abutting plate and the movable abutting arc plate are matched to stably arrange the hydraulic cylinder barrel of the agricultural machine in a fixed space, the hydraulic cylinder barrel of the agricultural machine is circumferentially fixed and protected, and the shaking generated during operation can be uniformly dispersed, so that the operation position is always stable. In this process, the arc-shaped abutting plate and the movable abutting arc plate can adjust the actual operation position according to actual use requirements, so that the application range of the tool is further improved. Compared with the conventional hydraulic cylinder barrel fixing technology of agricultural machines at the present stage, the application has the advantages of flexible use, convenient operation, wide application range and high stability. BRIEF DESCRIPTION OF DRAWINGS
[0026] Figure 1 A structural schematic view of the agricultural machine hydraulic cylinder barrel machining positioning tool is provided for the utility model;
[0027] Figure 2 A structural schematic view of the bottom structure of the assembly tool table of the agricultural machine hydraulic cylinder barrel machining positioning tool is provided for the utility model;
[0028] Figure 3 For Figure 1 An enlarged structural schematic view of the middle A;
[0029] Figure 4 A structural schematic view of the assembly hollow plate, the fixed extension tooth plate and the mounting arc-shaped abutting plate of the agricultural machine hydraulic cylinder barrel machining positioning tool is provided for the utility model;
[0030] Figure 5 ForFigure 1 Structure schematic view amplified at middle B.
[0031] Legend:
[0032] 1, assembly tooling table; 2, assembly sliding block; 3, assembly hollow plate; 4, assembly sleeve block; 5, assembly support lug; 6, assembly rotating shaft; 7, assembly support plate; 8, adjusting block; 9, guide rod; 10, adjusting sleeve block; 11, adjusting support lug; 12, adjusting rotating shaft; 13, adjusting motor; 14, adjusting bidirectional screw rod; 15, movable L-shaped block; 16, movable motor; 17, movable rod; 18, second movable gear; 19, fixed extension toothed plate; 20, fixed motor; 21, mounting arc abutting plate; 22, mounting support; 23, mounting motor; 24, mounting rod; 25, mounting gear; 26, movable concave block; 27, movable rotating shaft; 28, first movable gear; 29, movable abutting arc plate. DETAILED DESCRIPTION
[0033] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.
[0034] Referring to Figures 1 to 3 The utility model provides a kind of agricultural machinery hydraulic cylinder barrel processing positioning tool provided by the utility model, including assembly tooling table 1, it is equipped with two symmetrical assembly grooves, arbitrary The assembly groove is through the assembly tooling table 1 along the thickness direction of the assembly tooling table 1, assembly sliding groove is slidably connected with assembly sliding block 2, assembly sliding block 2 two ends are fixedly connected with assembly hollow plate 3 and assembly sleeve block 4, assembly sleeve block 4 side wall is fixedly connected with assembly support lug 5, assembly support lug 5 bottom is rotatably connected with assembly support plate 7 by assembly rotating shaft 6, the bottom of assembly tooling table 1 is connected with adjusting assembly, adjusting assembly includes the two adjusting blocks 8 of the bottom of assembly tooling table 1 fixed connection, two adjusting blocks 8 are fixedly connected with guide rod 9, guide rod 9 outer wall is movably sleeved with two adjusting sleeve blocks 10, adjusting sleeve block 10 two ends are fixedly connected with adjusting support lug 11, adjusting support lug 11 bottom is rotatably connected with its corresponding assembly support plate 7 by adjusting rotating shaft 12, one of adjusting block 8 surface is fixedly connected with adjusting motor 13, adjusting motor 13 output end is fixedly connected with adjusting bidirectional screw rod 14, adjusting bidirectional screw rod 14 end is through one of adjusting block 8 and is rotatably connected with another adjusting block 8, two adjusting sleeve blocks 10 are threadedly connected with the outer wall of adjusting bidirectional screw rod 14, by the effect that adjusting motor 13 drives adjusting bidirectional screw rod 14 to rotate.
[0035] Further, based on the above structure, by adjusting the motor 13 to drive the bidirectional screw 14 to rotate around its axis, at this time, the adjusting block 8 can be moved along the bidirectional screw 14 under the guidance of the guide rod 9 through the threaded cooperation between them and the bidirectional screw 14, and then sequentially drive the assembly support plate 7 and the assembly block 4 to move along the assembly sliding groove, thereby driving the assembly hollow plate 3 to move along the assembly sliding groove through the assembly block 4.
[0036] Referring to Figure 1 and Figure 4 As shown, the assembly hollow plate 3 is slidably connected with a fixed extension tooth plate 19 inside, one end of the fixed extension tooth plate 19 is fixedly connected with a fixed baffle, the side wall of the fixed baffle is fixedly connected with a fixed motor 20, the output shaft of the fixed motor 20 penetrates through the fixed baffle and is fixedly connected with an installation arc-shaped abutting plate 21, the two arc-shaped abutting plates 21 are fixed spaces, the side wall of the assembly hollow plate 3 is provided with a mounting groove, the mounting gear 25 is arranged inside the assembly hollow plate 3 through the mounting groove and is in meshing connection with the fixed extension tooth plate 19. The side wall of the assembly hollow plate 3 is connected with an installation assembly for adjusting the fixed extension tooth plate 19 to move, the installation assembly includes two installation brackets 22 fixedly connected with the side wall of the assembly hollow plate 3, one surface of one of the installation brackets 22 is fixedly connected with an installation motor 23, the output end of the installation motor 23 is fixedly connected with an installation rod 24, the installation rod 24 penetrates through one of the installation brackets 22 and is rotatably connected with the other installation bracket 22, the outer side wall of the installation rod 24 is fixedly sleeved with an installation gear 25, the installation gear 25 is in meshing connection with the corresponding fixed extension tooth plate 19, and the installation motor 23 plays a role in driving the installation rod 24 to rotate.
[0037] Further, in this embodiment, the installation motor 23 can drive the installation gear 25 connected to the installation rod 24 to rotate around its axis, thereby driving the fixed extension tooth plate 19 in meshing connection therewith, so as to realize the effect of converting the rotary driving action into linear driving action. Based on this, not only can the precise control of the lifting movement of the fixed extension tooth plate 19 be improved, but also the shaking generated during the movement can be reduced, thereby improving the use stability and prolonging the service life.
[0038] Referring to Figure 1 and Figure 5As shown, the mounting arc-shaped abutting plate 21 is connected with the movable assembly on both sides, the mounting arc-shaped abutting plate 21 is connected with the movable abutting arc plate 29 through the movable assembly. The movable assembly comprises a movable concave block 26 fixedly connected with the surface of the mounting arc-shaped abutting plate 21, a movable rotating shaft 27 rotatably connected between the inner walls of the movable concave block 26, a movable abutting arc plate 29 fixedly sleeved with the outer side wall of the movable rotating shaft 27, and the movable abutting arc plate 29 is movable close to / distant from the fixed space. Specifically, one end of the movable rotating shaft 27 penetrates through the movable concave block 26 and is fixedly connected with a first movable gear 28, the surface of the mounting arc-shaped abutting plate 21 is fixedly connected with a movable L-shaped block 15, the top of the movable L-shaped block 15 is fixedly connected with a movable motor 16, the output end of the movable motor 16 is fixedly connected with a movable rod 17, the tail end of the movable rod 17 penetrates through the movable L-shaped block 15 and is fixedly connected with a second movable gear 18, the second movable gear 18 is meshingly connected with the first movable gear 28, and the movable motor 16 plays a role of driving the movable rod 17 to rotate.
[0039] Further, in the embodiment, the second movable gear 18 is driven to rotate by the movable motor 16, which in turn drives the first movable gear 28 meshed therewith, thereby realizing the rotational driving of the movable abutting arc plate 29, so as to realize the purpose of the movable abutting arc plate 29 close to / distant from the machining space.
[0040] The overall working process and principle of the tool are described below: when in use, first start the mounting motor 23, drive the mounting gear 25 on the mounting rod 24 to rotate through the mounting motor 23, because the mounting gear 25 is meshed with the corresponding fixed extension toothed plate 19, so as to drive the fixed extension toothed plate 19 to slide along the inside of the assembly hollow plate 3, then the fixed extension toothed plate 19 also drives the mounting arc-shaped abutting plate 21 on the fixed baffle to adjust to the appropriate height, to ensure the adjustment effect.
[0041] Then start the adjusting motor 13, drive the adjusting bidirectional screw 14 to rotate through the adjusting motor 13, then the two adjusting sleeve blocks 10 are close to / distant from each other along the direction of the adjusting bidirectional screw 14, at the same time, the adjusting sleeve block 10 is movably sleeved with and guided by the outer side wall of the guide rod 9, then the adjusting lug 11 on the adjusting sleeve block 10 also drives the assembly support plate 7 on the adjusting rotating shaft 12 to move after deflection, so that the assembly support plate 7 also drives the assembly lug 5 on the assembly rotating shaft 6 to move, because the assembly lug 5 is fixedly installed with the assembly sleeve block 4, then the assembly sleeve block 4 also drives the assembly sliding block 2 to slide in the assembly sliding groove, then the assembly sliding block 2 also drives the assembly hollow plate 3 to move, so that the mounting arc-shaped abutting plate 21 on the assembly hollow plate 3 also moves, then the mounting arc-shaped abutting plate 21 abuts the two sides of the material to ensure the adjustment and abutting effect.
[0042] With the starting of the movable motor 16, the second movable gear 18 on the movable rod 17 is driven to rotate by the movable motor 16, and then the movable shaft 27 and the movable abutting arc plate 29 on the first movable gear 28 are also driven to rotate by the second movable gear 18, so that the movable abutting arc plate 29 approaches and abuts against the material, ensuring the movable abutting effect.
[0043] Finally, the fixed motor 20 is started, and the material abutting against the installation arc-shaped abutting plate 21 is driven to rotate to the appropriate angle by the fixed motor 20, so as to adjust and process, ensuring the movable processing effect.
[0044] Based on the above structure, in one aspect, the adjusting assembly is used to make the adjusting block, the guide rod, the adjusting sleeve block, the adjusting lug, the adjusting shaft, the adjusting motor and the adjusting bidirectional screw cooperate, so that the two adjusting sleeve blocks are moved closer to or away from each other along the direction of the adjusting bidirectional screw by rotating the adjusting bidirectional screw driven by the adjusting motor, and the assembly lug on the adjusting shaft is also moved after deflection by the adjusting lug on the adjusting sleeve block, so that the assembly lug also drives the assembly lug and the assembly sleeve block on the assembly shaft to move, and then the assembly sleeve block also drives the assembly sliding block to slide in the assembly sliding groove, and then the assembly sliding block also drives the assembly hollow plate to move, so that the installation arc-shaped abutting plate on the assembly hollow plate also moves and abuts against the material on both sides. The movable assembly is used to make the movable concave block, the movable shaft, the first movable gear, the movable abutting arc plate, the movable L-shaped block, the movable motor, the movable rod and the second movable gear cooperate, so that the second movable gear on the movable rod is rotated by the movable motor, and then the movable shaft and the movable abutting arc plate on the first movable gear are also rotated by the second movable gear, so that the movable abutting arc plate approaches and abuts against the material, and then the material abutting against the installation arc-shaped abutting plate is rotated to the appropriate angle by the fixed motor, so that the workpiece is tightly pressed, manual pressing processing is not needed, and the use effect is improved.
[0045] On the other hand, the installation assembly is used to make the installation support, the installation motor, the installation rod and the installation gear cooperate, so that the installation gear is rotated by the installation motor, and then the fixed extension toothed plate is slid along the inside of the assembly hollow plate, so that the fixed baffle on the fixed extension toothed plate drives the installation arc-shaped abutting plate to adjust to the appropriate height, thereby being able to adaptively fix the agricultural machine hydraulic cylinder barrel according to the actual use requirements of the agricultural machine hydraulic cylinder barrel, and further realize the effect of improving the use stability of the agricultural machine hydraulic cylinder barrel in all directions.
[0046] Finally, it should be noted that: the above only for the preferred embodiments of the present application, and is not intended to limit the present application, although the foregoing embodiments of the present application has been described in detail, for the skilled in the art, it still can be modified, or for part of the technical features of the equivalent replacement, the spirit and principles of the present application, made any modification, equivalent replacement, improvement, etc., should be included within the scope of the present application.
Claims
1. A positioning fixture for machining the cylinder barrel of an agricultural machinery hydraulic cylinder, comprising an assembly fixture table (1), characterized in that: The assembly tooling table (1) is provided with two symmetrically arranged assembly slots. Any one of the assembly slots penetrates the assembly tooling table (1) along the thickness direction. An assembly slider (2) is slidably connected inside the assembly slot. An assembly hollow plate (3) and an assembly block (4) are fixedly connected to both ends of the assembly slider (2). An assembly lug (5) is fixedly connected to the side wall of the assembly block (4). An assembly support plate (7) is rotatably connected to the assembly lug (5). An adjustment component is connected to the bottom of the assembly tooling table (1). The adjustment component is connected to the assembly support plate (7). The hollow assembly plate (3) is internally connected to a fixed extension toothed plate (19). One end of the fixed extension toothed plate (19) is connected to a fixed motor (20). The output shaft of the fixed motor (20) is connected to an arc-shaped clamping plate (21). There is a fixed space between the two arc-shaped clamping plates (21). Movable clamping arc plates (29) are connected to both sides of the arc-shaped clamping plate (21). The movable clamping arc plates (29) can move closer to / away from the fixed space. The arc-shaped clamping plate (21) is connected to the movable clamping arc plate (29) through a movable component. The movable component includes a first movable gear (28) and a second movable gear (18) that mesh with each other. The second movable gear (18) is set on the movable clamping arc plate (29) and the arc-shaped clamping plate (21).
2. The positioning fixture for machining the cylinder barrel of an agricultural machinery hydraulic cylinder according to claim 1, characterized in that: The adjustment assembly includes two adjustment blocks (8) fixedly connected to the bottom of the assembly tooling table (1), a guide rod (9) fixedly connected between the two adjustment blocks (8), two adjustment sleeves (10) movably sleeved on the outer side wall of the guide rod (9), and the assembly support plate (7) rotatably connected to the adjustment sleeves (10).
3. The positioning fixture for machining the cylinder barrel of an agricultural machinery hydraulic cylinder according to claim 2, characterized in that: Both ends of the adjusting sleeve (10) are fixedly connected to adjusting lugs (11), and the adjusting lugs (11) are rotatably connected to their corresponding mounting plates (7). An adjusting motor (13) is fixedly connected to the surface of one of the adjusting blocks (8).
4. The positioning fixture for machining the cylinder barrel of an agricultural machinery hydraulic cylinder according to claim 3, characterized in that: The output end of the regulating motor (13) is fixedly connected to a bidirectional regulating screw (14). The end of the bidirectional regulating screw (14) passes through one of the regulating blocks (8) and is rotatably connected to the other regulating block (8). Both regulating sleeves (10) are threadedly connected to the outer wall of the bidirectional regulating screw (14) so as to move relatively closer to / away from each other.
5. The positioning fixture for machining the cylinder barrel of an agricultural machinery hydraulic cylinder according to claim 3, characterized in that: The mounting lug (5) is rotatably connected to the mounting plate (7) via the mounting shaft (6), and the adjusting lug (11) is rotatably connected to its corresponding mounting plate (7) via the adjusting shaft (12).
6. The positioning fixture for machining the cylinder barrel of an agricultural machinery hydraulic cylinder according to claim 1, characterized in that: The side wall of the assembly hollow plate (3) is connected to an installation component for adjusting the movement of the fixed extension toothed plate (19). The side wall of the assembly hollow plate (3) is provided with an installation groove. At least part of the installation component passes through the installation groove into the interior of the assembly hollow plate (3) and is connected to the fixed extension toothed plate (19).
7. The positioning fixture for machining the cylinder barrel of an agricultural machinery hydraulic cylinder according to claim 6, characterized in that: The mounting assembly includes two mounting brackets (22) fixedly connected to the side wall of the assembly hollow plate (3). One of the mounting brackets (22) is fixedly connected to a mounting motor (23). The output end of the mounting motor (23) is fixedly connected to a mounting rod (24). The end of the mounting rod (24) passes through one of the mounting brackets (22) and is rotatably connected to the other mounting bracket (22). The outer side wall of the mounting rod (24) is fitted with a mounting gear (25). The mounting gear (25) passes through the mounting groove into the interior of the assembly hollow plate (3) and meshes with the fixed extension toothed plate (19).
8. The positioning fixture for machining the cylinder barrel of an agricultural machinery hydraulic cylinder according to claim 1, characterized in that: A fixed baffle is fixedly connected to one end of the fixed extension tooth plate (19), and a fixed motor (20) is fixedly connected to the side wall of the fixed baffle. The output shaft of the fixed motor (20) passes through the fixed baffle and is fixedly connected to an arc-shaped clamping plate (21).
9. The positioning fixture for machining the cylinder barrel of an agricultural machinery hydraulic cylinder according to claim 1, characterized in that: The movable component includes a movable recess (26) fixedly connected to the surface of the mounting arc-shaped abutment plate (21), the movable recess (26) is rotatably connected to a movable shaft (27), the outer wall of the movable shaft (27) is fixedly sleeved with a movable abutment arc plate (29), one end of the movable shaft (27) passes through the movable recess (26) and is fixedly connected to a first movable gear (28); a movable L-shaped block (15) is fixedly connected to the surface of the mounting arc-shaped abutment plate (21), the top of the movable L-shaped block (15) is fixedly connected to a movable motor (16), the output end of the movable motor (16) is fixedly connected to a movable rod (17), the end of the movable rod (17) passes through the movable L-shaped block (15) and is fixedly connected to a second movable gear (18), the second movable gear (18) meshes with the first movable gear (28).