A recoil spring testing device

Abstract

The utility model relates to a recoil spring test fixture, including a support base on which a spring body limiting assembly is detachably mounted, an axial pressure rod capable of applying axial compression force to the spring body limited by it is arranged at the axial upper end of the spring body limiting assembly, a top platform supported on the support base is also arranged above the axial pressure rod, and a driving unit capable of driving the axial pressure rod to perform axial translation is installed on the lower surface of the top platform, wherein the spring body limiting assembly respectively arranges an outer sleeve limiting mechanism and an inner support positioning mechanism on the mounting platform in a manner of adjustable outer contour limiting and inner support positioning of the spring body, and the outer sleeve limiting mechanism and the inner support positioning mechanism are arranged in a coaxial manner. The utility model can adapt to recoil springs of various specifications and effectively limit the recoil springs to improve the accuracy of their compression detection.

Description

Technical Field

[0001] The utility model relates to the technical field of spring testing equipment, in particular to a recoil spring testing tool. Background Art

[0002] The recoil spring is a spring that slows down the backward movement of the bolt on an automatic or semi-automatic firearm and pushes it back to the front end. It is one of the key parts for realizing firearm automation. When the bolt moves back, the recoil spring absorbs part of the kinetic energy of the bolt and releases it when it is compressed and stretched, serving as the energy source for the bolt to recoil, feed and lock. There are single and multiple recoil springs, and single springs can be made of single-strand or multi-strand steel wire. Using multiple springs with smaller stiffness in parallel can produce a recoil spring with greater stiffness; using multi-strand springs as recoil springs can increase the service life.

[0003] When manufacturing recoil springs, it is necessary to conduct quality inspection on the finished recoil springs to reduce the shipment rate of defective products, improve the shipment yield and quality, and reduce the impact of defective products on use. The quality inspection of recoil springs usually includes appearance quality inspection and performance quality inspection. The performance quality inspection mainly includes the stiffness coefficient, dynamic characteristics and fatigue life of the recoil spring. At present, the conventional spring body test usually places the spring body in a tube body, and while limiting the two ends of the spring body through a seat structure, the distance between the two seat structures is changed by external force to achieve extrusion of the spring body, thereby achieving the measurement of the performance parameters of the spring body during compression deformation. However, since the sizes of the existing spring body outer sleeve and the inner support base are fixed, when faced with recoil springs of different sizes used in different firearms, it is impossible to effectively fix the ends and perform compression limiting on recoil springs of various specifications and different cross-sectional sizes. The adaptability and limiting stability of the detection tooling in actual use are poor. The recoil spring is prone to bending, deformation and displacement during compression testing, which leads to deviations in the actual compression amount of the recoil spring, reduces the accuracy of the test, causes errors in the measurement data, and affects the accuracy of the performance quality inspection of the recoil spring. Utility Model Content

[0004] The utility model aims to provide a recoil spring testing tool that can adapt to recoil springs of various specifications and effectively limit the recoil springs to improve the accuracy of compression detection, so as to solve the problem that the existing detection tool cannot adapt to recoil springs of various specifications, resulting in poor spring body limiting stability when testing different spring bodies, and the spring body is prone to abnormal deformation such as bending, resulting in low accuracy of test data.

[0005] The technical solution adopted by the utility model is: a recoil spring testing fixture, including a supporting base on which a spring body limiting assembly is detachably mounted, an axial pressure rod capable of applying axial compression force to the spring body limited by it is arranged at the axial upper end of the spring body limiting assembly, a top platform supported on the supporting base is also arranged above the axial pressure rod, and a driving unit capable of driving the axial pressure rod to perform axial translation is installed on the lower surface of the top platform, wherein the spring body limiting assembly respectively arranges an outer sleeve limiting mechanism and an inner support positioning mechanism on the mounting platform in a manner of adjustably limiting the outer contour of the spring body and positioning the inner support, and the outer sleeve limiting mechanism and the inner support positioning mechanism are arranged in a coaxial manner.

[0006] According to a preferred embodiment, a plurality of first guide grooves and second guide grooves radially parallel to the mounting table are circumferentially spaced apart on the table surface of the mounting table, wherein the first guide grooves and the second guide grooves are arranged at staggered intervals on the same circumferential line; and a sealing plate is provided at the open end formed by the first guide grooves and the second guide grooves penetrating the radial outer side wall of the table body of the mounting table.

[0007] According to a preferred embodiment, the sleeve limiting mechanism includes a first guide slider arranged in the first guide groove and a first screw rod passed through the first guide groove, and a plurality of the first guide sliders and the first screw rod are circumferentially spaced in a manner corresponding to the first guide groove; the first screw rod passes through the sealing plate and is threadedly connected to the sealing plate; the insertion front end of the first screw rod inserted into the first guide groove is rotatably connected to the first guide slider.

[0008] According to a preferred embodiment, the internal support positioning mechanism includes a second guide slider and a second screw rod arranged in the second guide groove, wherein the second screw rod is inserted into the second guide groove in a manner parallel to the groove direction of the second guide groove, and one end of the second screw rod passes through the sealing plate and extends to the radially outer side of the mounting platform; a plurality of second guide sliders and second screw rods are arranged at circumferential intervals in the same distribution as the second guide groove.

[0009] According to a preferred embodiment, a limiting arc plate extending to the top of the mounting platform is supported on the first guide slide block; an elastic rubber sleeve is also sleeved on the outer side of the columnar body constructed by a plurality of the limiting arc plates.

[0010] According to a preferred embodiment, a split plug rod is supported on the second guide slider, and the upper end of the rod body defined by the multiple split plug rods is also covered with a silicone tip sleeve.

[0011] According to a preferred embodiment, a scale parallel to the groove directions of the first guide groove and the second guide groove is also provided on the table surface of the mounting table.

[0012] According to a preferred embodiment, the axial pressure rod includes a transmission rod and a pressure block sleeved on the transmission rod, wherein the pressure block is detachably mounted on the axial lower section of the transmission rod.

[0013] According to a preferred embodiment, the top plate of the top platform is supported on the support base by a hydraulic telescopic rod, so that the top plate is suspended above the spring body limiting assembly in a height-adjustable manner.

[0014] According to a preferred embodiment, the driving unit that coincides with the central axis of the spring body limiting assembly is disposed on the lower surface of the top plate, and the output end of the driving unit is connected to the transmission rod.

[0015] The beneficial effects of the utility model are:

[0016] The spring body limiting assembly provided in the present application can change the actual cross-sectional size of the columnar shell and the inserted support rod defined by it as required, thereby constructing a contour with adjustable thickness, so that it can construct a columnar outer contour and annular gap space with adjustable size and radial gap width according to the size of the spring body to be measured at the time, thereby ensuring that it can stably position the end sleeve of the spring body while avoiding the defect of bending deformation of the spring body in the columnar shell when it is compressed, ensuring the stability and contraction of the spring body when it is compressed, so that the deformation of the spring body during performance testing is only compression deformation, so that the translation and driving force applied during the testing process are received by the spring body and converted into effective deformation, thereby improving the effectiveness and accuracy of the deformation, and then facilitating high-precision performance measurement of the recoil spring, improving the performance test effect of the recoil spring and the accuracy of screening out defective products, and improving the shipment yield of the recoil spring product. The spring body limiting assembly of the present application can define a column accommodating space with an adjustable size that always keeps a match with the outer contour size of the spring body, avoiding the defect of spring body bending due to the lack of side limit with high side wall fit during the spring body compression process when a conventional fixed-size tube cavity faces a spring body with a smaller cross-section, thereby improving the accuracy of detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a structural schematic diagram of an optimal recoil spring testing tooling proposed by the utility model;

[0018] Figure 2 It is a top view of a spring body limiting assembly of a preferred recoil spring testing tool proposed by the utility model.

[0019] Reference numerals list

[0020] 1: Support base; 2: Spring body limit assembly; 3: Axial pressure rod; 4: Top platform; 5: Drive unit; 21: Outer sleeve limit mechanism; 22: Inner support positioning mechanism; 23: Mounting platform; 31: Transmission rod; 32: Pressure block; 41: Top plate; 42: Hydraulic telescopic rod; 211: First guide slider; 212: First screw rod; 213: Limit arc plate; 214: Elastic rubber sleeve; 221: Second guide slider; 222: Second screw rod; 223: Split plug rod; 224: Silicone tip sleeve; 231: First guide groove; 232: Second guide groove; 233: Sealing plate; 234: Scale. DETAILED DESCRIPTION

[0021] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the utility model will be briefly introduced below in combination with the drawings and the descriptions of the embodiments or the prior art. Obviously, the following descriptions of the structures of the drawings are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0022] The technical solution provided by the present invention will be described in detail below by way of examples with reference to the accompanying drawings. It should be noted that the description of these examples is used to help understand the present invention, but does not constitute a limitation of the present invention. In some examples, some implementation methods are not described or are not described in detail because they belong to existing or conventional technologies.

[0023] In addition, the technical features recorded in this article, or the steps in all methods or processes disclosed, except for mutually exclusive features and / or steps, can also be combined in any suitable manner in one or more embodiments. For those skilled in the art, it is easy to understand that the steps or operation sequence of the methods related to the embodiments provided herein can also be changed. Any order in the drawings and embodiments is only for illustrative purposes and does not imply a requirement to follow a certain order unless it is explicitly stated that a certain order is required.

[0024] The serial numbers assigned to the components herein, such as "first", "second", etc., are only used to distinguish the objects described and do not have any order or technical meaning. The "connection" and "coupling" mentioned in this application, under reasonable circumstances (not constituting a self-contradiction), include direct and indirect connections (couplings).

[0025] The following is a detailed description with reference to the accompanying drawings.

[0026] Example 1

[0027] The present application provides a recoil spring testing tool, which includes a supporting base 1, a spring body limiting assembly 2, an axial pressure rod 3, a top platform 4 and a driving unit 5.

[0028] according to Figure 1 In a specific embodiment shown, a spring body limiting assembly 2 is detachably mounted on the upper end surface of a support base 1. An axial pressure rod 3 capable of applying an axial compression force to the spring body limited by the spring body limiting assembly 2 is arranged at the axial upper end thereof. A top platform 4 supported on the support base 1 is also arranged above the axial pressure rod 3. A driving unit 5 capable of driving the axial pressure rod 3 to perform axial translation is mounted on the lower surface of the top platform 4. The spring body limiting assembly 2 provided in the present application can change the actual cross-sectional size of the columnar shell and the inserted support rod defined by it as required, thereby constructing a contour with adjustable thickness, so that it can construct a columnar outer contour and annular gap space with adjustable size and radial gap width according to the size of the spring body to be measured at the time, thereby ensuring that it can stably position the end sleeve of the spring body while avoiding the defect of bending deformation of the spring body in the columnar shell when compressed, ensuring the stability and contraction of the spring body when compressed, so that the deformation of the spring body during performance testing is only compression deformation, so that the translation and driving force applied during the testing process are received by the spring body and converted into effective deformation, thereby improving the effectiveness and accuracy of the deformation, and then facilitating the high-precision performance measurement of the recoil spring, improving the performance test effect of the recoil spring and the accuracy of screening out defective products, and improving the shipment yield of the recoil spring product. The spring body limiting assembly 2 of the present application can define a column accommodating space with an adjustable size that always keeps a match with the outer contour size of the spring body, avoiding the defect of spring body bending due to the lack of side limit with high side wall fit during the spring body compression process when a conventional fixed-size tubular cavity faces a spring body with a smaller cross-section, thereby improving the accuracy during detection.

[0029] Preferably, a slide groove for slidingly installing the spring body limiting assembly 2 is provided on the support base 1, and the lower part of the mounting platform 23 of the spring body limiting assembly 2 is provided with an outer contour matching the slide groove, so that the spring body limiting assembly 2 can slide on the support base 1 as required, so as to facilitate the insertion of the spring body to be tested from the upper end opening of the spring body limiting assembly 2. In addition, the sliding clamping method also facilitates the disassembly of the spring body limiting assembly 2 for maintenance and replacement of parts.

[0030] Preferably, the spring body limiting assembly 2 includes an outer sleeve limiting mechanism 21, an inner support positioning mechanism 22 and a mounting platform 23. Further preferably, the outer sleeve limiting mechanism 21 and the inner support positioning mechanism 22 are arranged on the mounting platform 23 in a manner that the outer contour of the spring body is limited and the inner support is positioned respectively in an adjustable manner. Specifically, the outer sleeve limiting mechanism 21 and the inner support positioning mechanism 22 are arranged in a coaxial manner. The outer sleeve limiting mechanism 21 provided in the present application can construct a cylindrical cavity with an adjustable cross-sectional size according to requirements, so as to perform outer contour adaptation and positioning on recoil springs of different sizes, so as to limit the recoil spring to only deform in the axial direction when compressed without causing the problem of bending of the spring body axis, thereby ensuring the accuracy of the deformation amount, so as to improve the accuracy of the test results during compression deformation, avoid the problem that the spring body axis bends and causes its actual compression amount to be less than the translation amount of the power loading end, eliminate the detection error caused by abnormal bending deformation, and improve the detection effect and quality. The inner support positioning mechanism 22 provided in the present application can construct an inner support rod body with an adjustable cross-sectional size, so that it can be used to limit the insertion sleeve of the recoil spring, so that there is no sleeve gap on the inner support positioning mechanism 22 for the recoil spring, so as to accurately locate the recoil spring's test position, avoid the recoil spring body from lateral displacement during compression deformation and reset rebound, and reduce the impact pressure and translation amount applied to it by the performance test, so as to ensure that the recoil spring can effectively and fully receive the driving action and complete the compression deformation and buffering vibration reduction required for the performance test. The mounting platform 23 provided in the present application can effectively limit the radial translation amount generated by the outer sleeve limiting mechanism 21 and the inner support positioning mechanism 22, so as to ensure the stability of the inner and outer limiting structures constructed by the two.

[0031] Preferably, the outer sleeve limiting mechanism 21 includes a first guide slider 211 disposed in the first guide groove 231 and a first screw 212 penetrating the first guide groove 231. Preferably, a plurality of first guide sliders 211 and first screws 212 are arranged circumferentially at intervals in a manner corresponding to the first guide groove 231. Further preferably, the first screw 212 penetrates the baffle plate 233 and is threadedly connected to the baffle plate 233. Preferably, the insertion front end of the first screw 212 inserted into the first guide groove 231 is rotationally connected to the first guide slider 211 to control the translation position of the first guide slider 211 in the first guide groove 231. Specifically, the first screw 212 can change its insertion length in the first guide groove 231 by screwing, thereby changing the position of the first guide slider 211 in the first guide groove 231. Preferably, a limiting arc plate 213 extending to the top of the mounting platform 23 is supported on the first guide slider 211. Specifically, preferably, the multiple limiting arc plates 213 corresponding to the first guide slider 211 cooperate with each other to define a cylindrical cavity with an adjustable cross-sectional size to adapt to spring bodies with different cross-sectional sizes. Preferably, in a preferred embodiment, an elastic rubber sleeve 214 is also sleeved on the outside of the columnar body constructed by the multiple limiting arc plates 213 of the present application. The elastic rubber sleeve 214 can assist in constructing a relatively closed side wall annular surface, thereby effectively simulating a more suitable real environment state of the recoil spring when in use, so as to improve the effectiveness of the recoil spring performance test. Preferably, an arc metal strip is embedded in the elastic rubber sleeve 214 to ensure that it can construct a roughly circular outer sleeve annular wall structure under the action of the arc metal strip and the limiting arc plate 213. The elastic rubber sleeve 214 provided in the present application is a further improvement on the technical solution and is not a necessary structure of the present application.

[0032] Preferably, the inner support positioning mechanism 22 includes a second guide slider 221 and a second screw 222 arranged in the second guide groove 232. Preferably, the second screw 222 is inserted into the second guide groove 232 in a manner parallel to the slotting direction of the second guide groove 232. Further preferably, one end of the second screw 222 penetrates the blocking plate 233 and extends to the radially outer side of the mounting platform 23. Preferably, a plurality of second guide sliders 221 and second screws 222 are arranged at intervals in the circumferential direction in the same manner as the second guide groove 232. Preferably, a split plug rod 223 is supported on the second guide slider 221. The split plug rod 223 is inserted into the spring body to cooperate with the limit arc plate 213 to limit the work position to be tested of the spring body. Specifically, a plurality of split plug rods 223 arranged at intervals in the circumferential direction can cooperate with each other to define a rod structure with an adjustable cross-sectional diameter, so as to position spring bodies of different sizes in accordance with the inner diameter size of the cross section of the spring body. Preferably, the upper end of the rod body defined by the multiple split insertion rods 223 is also sleeved with a silicone tip sleeve 224. The silicone tip sleeve 224 provided in the present application can form a closed end sleeve shell, so that the end of the inner insertion rod body constructed by the multiple split insertion rods 223 can be more easily inserted into the recoil spring to be tested.

[0033] Preferably, a plurality of first guide grooves 231 and second guide grooves 232 are circumferentially spaced and radially parallel to the table surface of the mounting table 23. Further preferably, the first guide grooves 231 and the second guide grooves 232 are arranged alternately and spaced on the same circumferential line. Preferably, a blocking plate 233 is provided at the open end formed by the first guide grooves 231 and the second guide grooves 232 penetrating the radial outer side wall of the table body of the mounting table 23. Preferably, a scale 234 parallel to the slotting directions of the first guide grooves 231 and the second guide grooves 232 is also provided on the table surface of the mounting table 23. The scale 234 is used to mark and confirm the lengths of the first screw rod 212 and the second screw rod 222 inserted into the first guide groove 231 and the second guide groove 232 respectively, so as to adjustably pre-set the size of the cross-section of the columnar cavity defined by the multiple limit arc plates 213 and the cross-section of the rod structure defined by the multiple split insertion rods 223, and then define the gap annular cavity for accommodating the spring body by cooperating with the inner and outer annular surfaces, thereby defining the installation position of the spring body and avoiding undesirable deformation of the spring body such as bending during compression, thereby improving the accuracy of the measurement data.

[0034] Preferably, the axial pressure rod 3 includes a transmission rod 31 and a pressure block 32 sleeved on the transmission rod 31. Preferably, the pressure block 32 is detachably mounted on the axial lower section of the transmission rod 31, and is provided with a variety of specifications with different cross-sectional sizes to fit columnar cavities of different sizes, thereby effectively transmitting pressure to springs of different cross-sectional sizes.

[0035] Preferably, the top plate 41 of the top platform 4 is supported on the support base 1 by a hydraulic telescopic rod 42, so that the top plate 41 is suspended above the spring body limit assembly 2 in a height-adjustable manner. Further preferably, a driving unit 5 coinciding with the central axis of the spring body limit assembly 2 is provided on the lower surface of the top plate 41. Preferably, the output end of the driving unit 5 is connected to a transmission rod 31 to drive the transmission rod 31 to translate on the central axis of the spring body limit assembly 2. Preferably, the driving unit 5 can select a general-purpose precision electronic universal material testing machine in the prior art, for example, Instron's 5565 precision electronic universal material testing machine.

[0036] The working principle of this application is:

[0037] The outer sleeve limiting mechanism 21 and the inner support positioning mechanism 22 are adjusted according to the outer diameter and inner diameter of the cross section of the recoil spring to be tested. Specifically, the cross section of the columnar cavity formed by the circumferentially spaced limiting arc plates 213 is changed by screwing the first screw 212 to match the outer contour of the spring body, so as to avoid the axial bending of the spring body during compression and other undesirable phenomena; the cross section of the inner plug rod constructed by the circumferentially spaced split plug rods 223 is changed by screwing the second screw 222, so that the inner plug rod can match the inner annular surface contour of the spring body to limit the installation position of the spring body, so as to prevent the spring body from shifting and other displacement movements that affect the test accuracy.

[0038] The spring body is inserted from the circumferential upper end of the columnar cavity, and a transmission rod 31 detachably connected to the drive unit 5 is inserted axially above the spring body, and the hydraulic telescopic rod 42 is raised and lowered to make the drive unit 5 descend, thereby connecting the drive unit 5 with the axial upper end of the transmission rod 31 partially inserted into the spring body, so that the transmission rod 31 can descend under the drive of the drive unit 5 and squeeze the spring body, wherein the cross-sectional size of the pressure block 32 pre-mounted on the transmission rod 31 is adapted to the cross-sectional size of the spring body of the recoil spring, so as to effectively compress the spring body to undergo compression deformation.

[0039] The present utility model is not limited to the above optional implementation modes. Anyone can derive other various forms of products under the inspiration of the present utility model. However, no matter what changes are made in the shape or structure, all technical solutions that fall within the scope of the claims of the present utility model fall within the protection scope of the present utility model. Those skilled in the art should understand that the present utility model specification and its drawings are illustrative and do not constitute limitations on the claims. The protection scope of the present utility model is defined by the claims and their equivalents. Throughout the text, the features guided by "preferably" are only an optional method and should not be understood as having to be set. Therefore, the applicant reserves the right to abandon or delete the relevant preferred features at any time.

Claims

1. A recoil spring testing tool, comprising a support base (1) on which a spring body limit assembly (2) is detachably mounted, characterized in that: An axial pressure rod (3) capable of applying axial compression force to the spring body limited by the spring body is arranged at the axial upper end of the spring body limiting assembly (2), a top platform (4) supported on the support base (1) is also arranged above the axial pressure rod (3), and a driving unit (5) capable of driving the axial pressure rod (3) to perform axial translation is installed on the lower surface of the top platform (4), wherein: The spring body limiting assembly (2) respectively arranges an outer sleeve limiting mechanism (21) and an inner support positioning mechanism (22) on a mounting platform (23) in a manner that the outer contour of the spring body is limitable and the inner support is positioned, and the outer sleeve limiting mechanism (21) and the inner support positioning mechanism (22) are arranged in a coaxial manner.

2. The recoil spring testing device according to claim 1, characterized in that: A plurality of first guide grooves (231) and second guide grooves (232) are circumferentially spaced and radially parallel to the surface of the mounting platform (23), wherein: The first guide groove (231) and the second guide groove (232) are arranged at staggered intervals on the same circumferential line; The first guide groove (231) and the second guide groove (232) penetrate through the radial outer side wall of the mounting platform (23) to form an opening end, and a blocking plate (233) is provided.

3. The recoil spring testing device according to claim 2, characterized in that: The outer sleeve limiting mechanism (21) comprises a first guide slider (211) arranged in the first guide groove (231) and a first screw rod (212) passing through the first guide groove (231). A plurality of the first guide sliders (211) and the first screw rods (212) are circumferentially spaced apart in a manner corresponding to the first guide grooves (231); The first screw rod (212) passes through the sealing plate (233) and is threadedly connected to the sealing plate (233); The front end of the first screw rod (212) inserted into the first guide groove (231) is rotatably connected to the first guide slider (211).

4. The recoil spring testing device according to claim 3, characterized in that: The inner support positioning mechanism (22) comprises a second guide slider (221) and a second screw rod (222) arranged in the second guide groove (232), wherein: The second screw rod (222) is inserted into the second guide groove (232) in a manner parallel to the slotting direction of the second guide groove (232), and one end of the second screw rod (222) passes through the blocking plate (233) and extends to the radial outer side of the mounting platform (23); A plurality of the second guide slide blocks (221) and the second screw rods (222) are arranged at intervals in the circumferential direction in the same distribution as the second guide grooves (232).

5. The recoil spring testing device according to claim 4, characterized in that: A limiting arc plate (213) extending to the top of the mounting platform (23) is supported on the first guide sliding block (211).

6. The recoil spring testing device according to claim 5, characterized in that: A split insert rod (223) is supported on the second guide slider (221). The upper end of the rod body defined by the plurality of split insertion rods (223) is also sleeved with a silicone tip sleeve (224).

7. The recoil spring testing device according to claim 6, characterized in that: A scale (234) is also provided on the surface of the mounting platform (23) and is parallel to the slotting directions of the first guide groove (231) and the second guide groove (232).

8. The recoil spring testing device according to claim 7, characterized in that: The axial pressure rod (3) comprises a transmission rod (31) and a pressure block (32) sleeved on the transmission rod (31), wherein: The pressure block (32) is detachably mounted on the axial lower section of the transmission rod (31).

9. The recoil spring testing device according to claim 8, characterized in that: The top plate (41) of the top platform (4) is supported on the support base (1) via a hydraulic telescopic rod (42), so that the top plate (41) is suspended above the spring body limiting assembly (2) in a height-adjustable manner.

10. The recoil spring testing device according to claim 9, characterized in that: The lower surface of the top plate (41) is provided with the driving unit (5) which coincides with the central axis of the spring body limiting assembly (2), and the output end of the driving unit (5) is connected to the transmission rod (31).

Images