Motor home axle welding device and method
By designing the RV axle welding device with rotating mechanism and drive components, the cumbersome problems of axle flip and welding are solved, and the effect of efficient welding and cleaning of welding slag is achieved, and the cost is reduced.
Patent Information
- Application Number
- CN202510871642.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-26
- Publication Date
- 2025-07-25
- Estimated Expiration
- Not applicable · inactive patent
AI Technical Summary
When the existing RV axle welding device needs to weld both sides of the axle, it is necessary to disassemble and flip the axle, resulting in cumbersome and time-consuming welding process, increasing labor and time costs.
A motorhome axle welding device is designed that includes a rotating mechanism and a drive assembly. The screw is rotated by driving the motor, and the sliding sleeve and ball roll along the slide chute is driven to realize the flip of the axle and the rotation of the fixed assembly, allowing direct welding to be performed on the other side of the axle, and the welding slag is cleaned by tapping the assembly.
The flip and welding of the axle without disassembly is achieved, the welding efficiency is improved, labor and time costs are reduced, and the welding slag cleaning efficiency and quality are improved.
Smart Images

Figure CN120362865A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of axle welding, and specifically relates to a welding device and method for a motorhome axle. Background Art
[0002] The motorhome axle is an important component in a motorhome. It is connected to the vehicle frame (or integral body) through a suspension, and wheels are installed at both ends, playing a crucial role during the driving of the motorhome. Then, during the processing, welding treatment is required for it; Currently, the traditional motorhome axle welding device steadily places the axle to be welded on a special fixing component. After the axle is fixed, the welding component starts to play its key role. The welding component generally consists of parts such as a welding torch and a wire feeding mechanism. The operator manipulates the welding torch to move along the preset weld seam on the surface of the axle, and at the same time, the wire feeding mechanism continuously and steadily feeds the welding wire. The welding wire melts under the action of a high-temperature electric arc and fills into the weld seam, thereby achieving the welding treatment on the surface of the axle.
[0003] However, in the actual welding work of motorhome axles, due to the design and structural characteristics of motorhome axles, in order to meet the requirements of their strength, stability, and connection with other components, it may be necessary to weld both sides of the axle. But the existing traditional welding devices have obvious limitations when dealing with this situation. When it is necessary to weld the other side of the axle, the operator has to first disassemble the axle with one side welded from the fixing component. After the disassembly, the axle also needs to be flipped so that its other side faces upward, and then it is re-fixed on the fixing component for another welding operation. The whole process is cumbersome and complex, and a large amount of manpower is required for each step. At the same time, it also takes a long time, which undoubtedly greatly increases the labor and time costs, and thus significantly reduces the welding efficiency. Summary of the Invention
[0004] To solve the problems raised in the above background art, the present invention provides a welding device and method for a motorhome axle.
[0005] To achieve the above object, the present invention provides the following technical solution: A welding device for a motorhome axle, including a base and a welding component, further including: A rotating mechanism, which is arranged at the top of the base. The rotating mechanism includes mounting seats fixedly connected to the top of the base, and the number of the mounting seats is two. A rotating disk is rotatably connected inside each of the two mounting seats. One side of the rotating disk is fixedly installed with a connecting rod. A sliding groove is formed on the surface of the connecting rod. A sliding sleeve is slidably sleeved on the surface of the connecting rod. A ball located inside the sliding groove is rotatably connected inside the sliding sleeve; A first driving component, which is arranged on one side of the mounting seat and can drive the sliding sleeve to move; A fixing component is arranged on one side opposite to two rotating discs and can fix the axle.
[0006] Preferably, the first driving component includes a mounting plate fixedly connected to one side of the mounting seat. A motor is fixedly installed at the top end of the mounting plate. A lead screw is fixedly installed at the output end of the motor. A threaded block is threadedly sleeved on the surface of the lead screw, and the top end of the threaded block is fixedly connected to the surface of the sliding sleeve.
[0007] Preferably, the fixing component includes a support seat fixedly connected to one side opposite to two rotating discs. Cylinders are fixedly installed at the top ends of the support seat on the opposite sides of the two rotating discs. An extrusion block is fixedly installed at the output shaft of the cylinder.
[0008] Preferably, it further includes: A second driving component is arranged on the other side of the mounting seat. The second driving component includes a fixed block fixedly connected to the other side of the mounting seat. A gear is rotatably connected inside the fixed block. A push rod is fixedly installed on one side of the gear and located on the outer surface of the fixed block. A rack is slidably connected inside the fixed block. The rack is elastically connected to the fixed block through an elastic member. An extrusion rod is slidably connected inside the fixed block, and one end of the extrusion rod is fixedly connected to the sliding sleeve; A knocking component is arranged at the top end of the base and can knock the surface of the axle.
[0009] Preferably, the knocking component includes a first limiting rod fixedly connected to the top end of the base. A sliding ring is slidably connected to the surface of the first limiting rod, and the push rod is located inside the sliding ring. A knocking block is fixedly installed at the top end of the sliding ring.
[0010] Preferably, it further includes: A limiting component is arranged on one side of the mounting plate. The limiting component includes a second limiting rod fixedly connected to one side of the mounting plate. A limiting block is slidably sleeved on the surface of the second limiting rod, and the top end of the limiting block is fixedly connected to the threaded block.
[0011] Preferably, the chute is designed to be inclined, and the surface of the ball is fully attached to the inner wall of the chute.
[0012] Preferably, a limiting ring is fixedly installed on the surface of the rotating disc and located inside the mounting seat, and the surface of the limiting ring is attached to the inner wall of the mounting seat.
[0013] Preferably, the first limiting rod is designed to be mirror-image and square, and the top end of the knocking block is designed to be arc-shaped.
[0014] A welding method for the axle of a motorhome is as follows: S1: First, the operator puts the axle into the support seat, and then drives the cylinder to lower the extrusion block to fix the axle. After the fixation is completed, the welding assembly is driven to weld the surface of the axle; S2: When welding is required on the other side, the motor is driven to rotate the screw rod, the threaded block slides on the surface of the screw rod, and can drive the sliding sleeve to slide on the surface of the connecting rod, while the ball rolls along the inner wall of the slide groove. During the rolling process, the connecting rod and the fixed component can be rotated, and then the fixed component will drive the unwelded part of the axle to flip to the bottom end of the welding component, and then the welding component can be driven again to weld it as a whole; S3: When the sliding sleeve moves, it will drive the extrusion rod to squeeze the air inside the fixed block. As the negative pressure is formed inside the fixed block, it will push the rack to move. The rack will drive the gear to rotate. The gear will drive the push rod to slide inside the sliding ring, which will push the sliding ring and the knocking block to move back and forth. During the movement of the knocking block, it will knock on the surface of the axle, so that the welding slag will be separated from the surface of the axle.
[0015] Compared with the prior art, the present invention has the following beneficial effects: The present invention drives the screw rod to rotate by driving the motor, the threaded block will slide on the surface of the screw rod, and can drive the sliding sleeve to slide on the surface of the connecting rod, and the ball rolls along the inner wall of the slide groove. During the rolling process, the connecting rod and the fixing component can be rotated, and then the fixing component will drive the unwelded part of the axle to flip to the bottom end of the welding component, and then the welding component can be driven again to weld it as a whole, and finally the driving component is driven to drive the rotating disk to flip the fixing component and the axle, and then the axle can be easily flipped to a suitable angle without disassembly, so that the welding personnel can directly perform welding operations on the other side of the axle, which greatly improves the welding efficiency and reduces the manpower and time costs. The present invention drives the extrusion rod to squeeze the air inside the fixed block when the sliding sleeve moves. As the negative pressure inside the fixed block is formed, the rack is pushed to move, and the rack drives the gear to rotate. The gear drives the push rod to slide inside the sliding ring, which pushes the sliding ring and the knocking block to move back and forth. During the movement of the knocking block, the surface of the axle is knocked. Finally, by utilizing the movement of the sliding sleeve, the extrusion rod is linked to make the knocking block continuously knock on the surface of the axle. Under the action of continuous vibration, the welding slag attached to the surface of the axle is gradually loosened and falls off, and there is no need for manual removal, which greatly improves the efficiency and quality of welding slag cleaning. BRIEF DESCRIPTION OF THE DRAWINGS
[0016] Figure 1 It is a schematic diagram of the structure of the present invention; Figure 2 It is a schematic diagram of the squint device of the present invention; Figure 3Schematic diagram showing the rotation mechanism of the present invention; Figure 4 For the present invention Figure 3 Enlarged schematic diagram of part A in; Figure 5 Schematic cross-sectional view of the fixing block of the present invention; Figure 6 Schematic diagram showing the second driving component of the present invention.
[0017] In the figure: 1, base; 2, welding assembly; 3, rotation mechanism; 301, mounting seat; 302, rotating disk; 303, connecting rod; 304, sliding groove; 305, sliding sleeve; 306, ball; 4, first driving component; 401, mounting plate; 402, motor; 403, lead screw; 404, threaded block; 5, fixing component; 501, support seat; 502, cylinder; 503, extrusion block; 6, second driving component; 601, fixing block; 602, gear; 603, push rod; 604, rack; 605, elastic member; 606, extrusion rod; 7, knocking component; 701, first limiting rod; 702, sliding ring; 703, knocking block; 8, limiting component; 801, second limiting rod; 802, limiting block; 9, limiting ring. Detailed implementation manners
[0018] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.
[0019] As Figures 1 to 6 shown, the present invention provides a welding device for a motorhome axle, including a base 1 and a welding assembly 2, and further including: A rotation mechanism 3, which is arranged at the top of the base 1. The rotation mechanism 3 includes a mounting seat 301 fixedly connected to the top of the base 1, and the number of the mounting seats 301 is two. The inside of both mounting seats 301 is rotatably connected with a rotating disk 302. One side of the rotating disk 302 is fixedly installed with a connecting rod 303. A sliding groove 304 is formed on the surface of the connecting rod 303. A sliding sleeve 305 is slidably sleeved on the surface of the connecting rod 303. A ball 306 located inside the sliding groove 304 is rotatably connected inside the sliding sleeve 305; A first driving component 4, which is arranged on one side of the mounting seat 301 and can drive the sliding sleeve 305 to move; A fixing component 5, which is arranged on the opposite sides of the two rotating disks 302 and can fix the axle.
[0020] Adopt the above solution: The operator installs the axle to be welded inside the fixing component 5, and the fixing component 5 can fix the axle. After the fixing is completed, the welding component 2 can be driven to weld its surface. After one side of the axle is welded, when the other side needs to be welded, the driving component 1 can be driven to make the sliding sleeve 305 slide on the surface of the connecting rod 303. During the sliding process, the ball 306 will be driven to roll along the inner wall of the chute 304. During the rolling process, the connecting rod 303 can be rotated. The connecting rod 303 will drive the rotating disk 302 and the fixing component 5 to rotate, so that the fixing component 5 will drive the un-welded part of the axle to be flipped to the bottom of the welding component 2, and then the welding component 2 can be driven again to perform overall welding on it. Finally, by driving the driving component 1, the rotating disk 302 drives the fixing component 5 and the axle to be flipped, so that the axle can be easily flipped to a suitable angle without disassembly, enabling the welder to directly perform welding operations on the other side of the axle, greatly improving the welding efficiency and reducing the labor and time costs.
[0021] As Figure 3 and Figure 5 shown, the driving component 1 includes a mounting plate 401 fixedly connected to one side of the mounting seat 301. A motor 402 is fixedly installed at the top of the mounting plate 401. A lead screw 403 is fixedly installed at the output end of the motor 402. A threaded block 404 is threadedly sleeved on the surface of the lead screw 403, and the top of the threaded block 404 is fixedly connected to the surface of the sliding sleeve 305.
[0022] Adopt the above solution: Through the design of the driving component 1, the motor 402 can be driven to rotate the lead screw 403. Since the lead screw 403 is threadedly connected to the threaded block 404, the threaded block 404 will slide on the surface of the rotating lead screw 403, and during the sliding process, it can drive the sliding sleeve 305 to slide on the surface of the connecting rod 303.
[0023] As Figure 5 shown, the fixing component 5 includes a support seat 501 fixedly connected to the opposite sides of the two rotating disks 302. On the opposite sides of the two rotating disks 302, air cylinders 502 are fixedly installed on the top of the support seat 501. An extrusion block 503 is fixedly installed at the output shaft of the air cylinder 502.
[0024] Adopt the above solution: Through the design of the fixing component 5, the two ends of the axle can be respectively placed inside the support seat 501, and then the air cylinder 502 can be driven to push the extrusion block 503 to descend by its output shaft. Then the surface of the extrusion block 503 will contact the surface of the axle, and thus the axle can be fixed to ensure the stability of welding.
[0025] As Figure 5 and Figure 6 shown, it further includes: The second driving component 6 is arranged on the other side of the mounting base 301. The second driving component 6 includes a fixing block 601 fixedly connected to the other side of the mounting base 301. A gear 602 is rotatably connected inside the fixing block 601. One side of the gear 602 is fixedly installed with a push rod 603 located on the outer surface of the fixing block 601. A rack 604 is slidably connected inside the fixing block 601. The rack 604 is elastically connected to the fixing block 601 through an elastic member 605. An extrusion rod 606 is slidably connected inside the fixing block 601, and one end of the extrusion rod 606 is fixedly connected to the sliding sleeve 305. The knocking component 7 is arranged at the top of the base 1 and can knock the surface of the axle.
[0026] Adopting the above scheme: Through the design of the second driving component 6, when the sliding sleeve 305 moves, it will drive the extrusion rod 606 to slide inside the fixing block 601. During the movement of the extrusion rod 606, the air inside the fixing block 601 will be squeezed. With the negative pressure inside the fixing block 601, the rack 604 will be pushed to move. When the rack 604 moves, the elastic member 605 will be compressed, and the rack 604 meshes with the gear 602. Then the rack 604 will drive the gear 602 to rotate, and the gear 602 will drive the push rod 603 to rotate. With the rotation of the push rod 603, the knocking component 7 will be driven to frequently knock the surface of the axle. By using the vibration generated by the knocking, the welding slag generated by welding will be separated from the surface of the axle, and then the fallen welding slag will fall into the collection groove at the top of the base 1.
[0027] Such as Figure 4 and Figure 5 As shown in the figure, the knocking component 7 includes a first limiting rod 701 fixedly connected to the top of the base 1. A sliding ring 702 is slidably connected to the surface of the first limiting rod 701, and the push rod 603 is located inside the sliding ring 702. A knocking block 703 is fixedly installed at the top of the sliding ring 702.
[0028] Adopting the above scheme: Through the design of the knocking component 7, during the rotation of the push rod 603, it will slide inside the sliding ring 702. During the sliding process, the sliding ring 702 and the knocking block 703 will be pushed to move reciprocally. During the movement of the knocking block 703, it will knock the surface of the axle. Finally, by using the movement of the sliding sleeve 305, the extrusion rod 606 is linked to make the knocking block 703 continuously knock the surface of the axle. Under the continuous vibration, the welding slag attached to the surface of the axle gradually loosens and falls off, thus eliminating the need for manual laborious removal, greatly improving the efficiency and quality of welding slag cleaning.
[0029] Such as Figure 3 and Figure 5 As shown in the figure, it further includes: The limiting component 8 is arranged on one side of the mounting plate 401. The limiting component 8 includes a second limiting rod 801 fixedly connected to one side of the mounting plate 401. A limiting block 802 is slidably sleeved on the surface of the second limiting rod 801, and the top end of the limiting block 802 is fixedly connected to the threaded block 404.
[0030] Adopting the above solution: Through the design of the limiting component 8, during the movement of the threaded block 404, the limiting block 802 will be driven to slide inside the second limiting rod 801. During the sliding process, the second limiting rod 801 can limit the moving direction of the threaded block 404 and the sliding sleeve 305 to ensure the normal movement of the threaded block 404 and the sliding sleeve 305.
[0031] As Figure 3 shown, the sliding groove 304 is inclined, and the surface of the ball 306 is fully attached to the inner wall of the sliding groove 304.
[0032] Adopting the above solution: Through the design of the sliding groove 304, since the sliding groove 304 is inclined and the surface of the ball 306 is fully attached to the inner wall of the sliding groove 304, the ball 306 will move along the inclined direction of the sliding groove 304, thereby driving the rotating disc 302 and the connecting rod 303 to rotate. Moreover, the surface of the ball 306 is smooth to ensure the smooth movement of the ball 306.
[0033] As Figure 3 and Figure 4 shown, a limiting ring 9 is fixedly installed on the surface of the rotating disc 302 and is located inside the mounting seat 301. The surface of the limiting ring 9 is attached to the inner wall of the mounting seat 301. The first limiting rod 701 is mirror-designed and square-shaped, and the top end of the knocking block 703 is arc-shaped.
[0034] Adopting the above solution: Through the design of the limiting ring 9, since the surface of the limiting ring 9 is attached to the inner wall of the mounting seat 301 and its size is larger than that of the rotating disc 302, when the rotating disc 302 rotates, the limiting ring 9 will rotate along with it, thereby being able to limit the rotating disc 302. Through the design of the first limiting rod 701 and the knocking block 703, since the first limiting rod 701 is mirror-designed, when the sliding ring 702 moves, the moving direction of the sliding ring 702 can be limited. And the top end of the knocking block 703 is arc-shaped, which can reduce the friction with the axle to ensure the normal rotation of the axle.
[0035] As Figures 1 to 6 shown, the welding method is as follows: S1: First, the operator places the axle inside the support seat 501, then drives the air cylinder 502 to lower the extrusion block 503 to fix the axle. After the fixing is completed, the welding assembly 2 is driven to weld the surface of the axle. S2: When welding is required on the other side, the drive motor 402 rotates the lead screw 403. The threaded block 404 slides on the surface of the lead screw 403 and can drive the sliding sleeve 305 to slide on the surface of the connecting rod 303. The ball 306 rolls along the inner wall of the chute 304. During the rolling process, the connecting rod 303 and the fixing assembly 5 can be rotated. Then, the fixing assembly 5 drives the unwelded part of the axle to be flipped to the bottom of the welding assembly 2, and then the welding assembly 2 can be driven again to perform overall welding on it; S3: When the sliding sleeve 305 moves, it drives the extrusion rod 606 to squeeze the air inside the fixed block 601. With the negative pressure formed inside the fixed block 601, the rack 604 is then pushed to move. The rack 604 drives the gear 602 to rotate, and the gear 602 drives the push rod 603 to slide inside the sliding ring 702, pushing the sliding ring 702 and the knocking block 703 to move reciprocally. During the movement of the knocking block 703, the surface of the axle is knocked, causing the welding slag to break away from the surface of the axle.
[0036] It should be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.
[0037] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.
Claims
1. A welding device for a motorhome axle, comprising a base (1) and a welding assembly (2), characterized in that, Also included are: A rotating mechanism (3) is provided at the top of the base (1). The rotating mechanism (3) includes a mounting seat (301) fixedly connected to the top of the base (1), and the number of the mounting seats (301) is two. A rotating disk (302) is rotatably connected inside each of the two mounting seats (301). A connecting rod (303) is fixedly installed on one side of the rotating disk (302). A chute (304) is formed on the surface of the connecting rod (303). A sliding sleeve (305) is slidably sleeved on the surface of the connecting rod (303). A ball (306) located inside the chute (304) is rotatably connected inside the sliding sleeve (305). A first driving assembly (4) is provided on one side of the mounting seat (301) and can drive the sliding sleeve (305) to move. A fixing assembly (5) is provided on the opposite sides of the two rotating disks (302) and can fix the axle.
2. The welding device for the RV axle according to claim 1, wherein: The first driving assembly (4) includes a mounting plate (401) fixedly connected to one side of the mounting seat (301). A motor (402) is fixedly installed at the top of the mounting plate (401). A lead screw (403) is fixedly installed at the output end of the motor (402). A threaded block (404) is threadedly sleeved on the surface of the lead screw (403), and the top of the threaded block (404) is fixedly connected to the surface of the sliding sleeve (305).
3. The welding device for the RV axle according to claim 1, characterized in that: The fixing assembly (5) includes a support seat (501) fixedly connected to the opposite sides of the two rotating disks (302). Cylinders (502) are fixedly installed at the top of the support seat (501) on the opposite sides of the two rotating disks (302). An extrusion block (503) is fixedly installed at the output shaft of the cylinder (502).
4. The welding device for the motorhome axle according to claim 1, characterized in that Also included are: A second driving assembly (6) is provided on the other side of the mounting seat (301). The second driving assembly (6) includes a fixing block (601) fixedly connected to the other side of the mounting seat (301). A gear (602) is rotatably connected inside the fixing block (601). A push rod (603) located on the outer surface of the fixing block (601) is fixedly installed on one side of the gear (602). A rack (604) is slidably connected inside the fixing block (601). The rack (604) is elastically connected to the fixing block (601) through an elastic member (605). An extrusion rod (606) is slidably connected inside the fixing block (601), and one end of the extrusion rod (606) is fixedly connected to the sliding sleeve (305). A knocking assembly (7) is provided at the top of the base (1) and can knock on the surface of the axle.
5. The welding device for the RV axle according to claim 4, characterized in that: The knocking assembly (7) includes a first limiting rod (701) fixedly connected to the top of the base (1). A sliding ring (702) is slidably connected to the surface of the first limiting rod (701), and the push rod (603) is located inside the sliding ring (702). A knocking block (703) is fixedly installed at the top of the sliding ring (702).
6. The welding device for the RV axle according to claim 2, wherein, Also included are: The limiting component (8) is arranged on one side of the mounting plate (401). The limiting component (8) includes a second limiting rod (801) fixedly connected to one side of the mounting plate (401). A limiting block (802) is slidably sleeved on the surface of the second limiting rod (801), and the top end of the limiting block (802) is fixedly connected to the threaded block (404).
7. The welding device for the car axle of a recreational vehicle according to claim 1, wherein: The chute (304) is designed to be inclined, and the surface of the ball (306) is fully attached to the inner wall of the chute (304).
8. The welding device for the motorhome axle according to claim 1, characterized in that: A limiting ring (9) located inside the mounting seat (301) is fixedly installed on the surface of the rotating disk (302), and the surface of the limiting ring (9) is attached to the inner wall of the mounting seat (301).
9. The welding device for the motorhome axle according to claim 5, characterized in that: The first limiting rod (701) is designed to be mirror-image and square, and the top end of the knocking block (703) is designed to be arc-shaped.
10. A welding method for a motorhome axle, using a motorhome axle welding device as described in any one of claims 1-9, characterized in that: The welding method is as follows: S1: First, the operator places the axle into the inside of the support seat (501), then drives the cylinder (502) to lower the extrusion block (503) to fix the axle. After the fixing is completed, the welding assembly (2) is driven to weld the surface of the axle. S2: When welding the other side is required, the driving motor (402) is driven to rotate the lead screw (403). The threaded block (404) will slide on the surface of the lead screw (403) and can drive the sliding sleeve (305) to slide on the surface of the connecting rod (303). The ball (306) rolls along the inner wall of the chute (304). During the rolling process, the connecting rod (303) and the fixing assembly (5) are rotated. Then the fixing assembly (5) drives the un-welded part of the axle to flip to the bottom end of the welding assembly (2), and then the welding assembly (2) is driven again to perform overall welding on it. S3: When the sliding sleeve (305) moves, it drives the extrusion rod (606) to extrude the air inside the fixed block (601). With the negative pressure formed inside the fixed block (601), the rack (604) is further pushed to move. The rack (604) drives the gear (602) to rotate. The gear (602) drives the push rod (603) to slide inside the sliding ring (702), and the sliding ring (702) and the knocking block (703) are pushed to move reciprocally. During the movement of the knocking block (703), the surface of the axle is knocked, causing the generated welding slag to break away from the surface of the axle.