An off-road truck rear axle reducer input bearing forced lubrication system

Abstract

A forced lubrication system for the input bearing of a rear axle reducer in an off-road truck includes a first oil pipe and a second oil pipe located outside the main drive housing and interconnected. The inlet end of the first oil pipe is connected to an oil sump inside the reducer housing. A one-way piston pump assembly is connected between the first and second oil pipes. The system also includes a first oil inlet passage located inside the main drive housing above the cam and connected to the outlet of the second oil pipe. A third oil inlet passage is connected between the outlet of the first oil inlet passage and the gap inside the main drive housing above the cam. Furthermore, the system includes a second oil inlet passage located inside the main drive housing above a second tapered roller bearing. The inlet end of the second oil inlet passage is connected to the first oil inlet passage, and the outlet end of the second oil inlet passage is connected to the high side end of the second tapered roller bearing via an oil inlet groove. Through the rational design of the component structure, the lubrication problem of the high-position support bearing in the rear axle reducer of the off-road truck is completely solved, significantly improving the reliability of the rear axle reducer.

Description

Technical Field

[0001] This invention belongs to the field of speed reducer technology, specifically relating to a forced lubrication system for the input bearing of a rear axle speed reducer for off-road trucks. Background Technology

[0002] Bearings are core components of all rotating machinery. Their reliability directly determines the lifespan of the equipment. This is especially true in the automotive industry, where bearings are crucial components of assemblies such as transmissions, reducers, and differentials. Besides the need for thorough bearing lifespan assessment during the design phase, the operating environment of the bearings during use is extremely important, particularly the adequacy of lubrication. Statistical analysis of bearing failure data from transmissions and reducers shows that high-temperature ablation is one of the most significant bearing failure modes. Therefore, bearing lubrication must be fully considered during the initial design of rotating machinery to avoid addressing high-temperature ablation failures after the fact.

[0003] With the rapid development of automotive technology, the application scenarios and user groups of off-road vehicles are becoming increasingly widespread, especially all-wheel-drive off-road vehicles such as medium and heavy-duty 6-wheel-drive off-road trucks. The power transmission path of these trucks mainly includes the engine, transfer case, transmission, rear axle reducer, and wheel-side reducers. Bearings are an indispensable key component in each of these transmission paths. Due to the overall vehicle layout, especially the input end of the rear axle reducer, which is often designed with a certain angle of elevation, the support bearing at the input end is positioned high. If the lubrication assessment for this high-positioned support bearing is insufficient during the initial design phase, it can lead to high-temperature failure due to poor lubrication during product use.

[0004] There are two main methods for lubricating bearings: splash lubrication and forced lubrication. However, splash lubrication cannot completely solve the lubrication problem for support bearings located in high positions, for example... Figure 2 The diagram shows a cross-sectional view of a rear axle reducer for an off-road truck. A first tapered roller bearing 10, a cam 11, and a second tapered roller bearing 12 are mounted on a drive gear 13. The central axis of the drive gear 13 forms a certain angle with the horizontal. The first tapered roller bearing 10 is close to the drive gear 13 and is lubricated by splash lubrication from the oil sump. The second tapered roller bearing 12, however, is positioned higher and farther from the reducer's oil sump, thus lacking sufficient lubrication. Currently, forced lubrication is commonly used. While forced lubrication increases costs compared to splash lubrication, it completely solves the problem of the higher-positioned support bearing. The cost of forced lubrication mainly lies in the complexity of the oil circuit and the cost of the oil pump assembly, with the oil pump assembly accounting for the largest share of the cost. Summary of the Invention

[0005] To address the aforementioned problems, the purpose of this invention is to provide a forced lubrication system for the input bearing of the rear axle reducer of an off-road truck, thereby solving the lubrication problem of the input bearing of the rear axle reducer of an off-road truck.

[0006] To achieve the above objectives, the technical solution adopted by the present invention includes:

[0007] A forced lubrication system for the input bearing of a rear axle reducer in an off-road truck includes a first oil pipe and a second oil pipe located outside the main drive housing and interconnected. The inlet end of the first oil pipe is connected to an oil sump inside the reducer housing. A one-way piston pump assembly is connected between the first oil pipe and the second oil pipe. The system also includes a first oil inlet passage located inside the main drive housing above the cam and connected to the outlet of the second oil pipe. A third oil inlet passage is connected between the outlet of the first oil inlet passage and the gap inside the main drive housing above the cam. The system further includes a second oil inlet passage located inside the main drive housing above a second tapered roller bearing. The inlet end of the second oil inlet passage is connected to the first oil inlet passage. The outlet end of the second oil inlet passage is connected to the high side end of the second tapered roller bearing via an oil inlet groove. A gap is left between the end of the oil inlet groove and the bearing cover. The inlet end of the second oil inlet passage is higher than the outlet end of the second oil inlet passage.

[0008] Preferably, the one-way plunger pump oil pumping assembly includes a piston unit that is in mechanical contact with the outer periphery of the cam, and also includes an oil inlet unit and an oil outlet unit that are connected to the sealing cavity of the piston unit. The inlet of the oil inlet unit is connected to the outlet end of the first oil pipe, and the outlet of the oil outlet unit is connected to the inlet end of the second oil pipe.

[0009] Preferably, the piston unit includes a pump spring seat located outside the main drive housing. The pump spring seat has a limiting shaft on the side facing the cam. A pump spring is coaxially sleeved on the limiting shaft. A plunger is connected to the free end of the pump spring. The plunger is in mechanical contact with the outer periphery of the cam, and there is a sealed piston cavity between the plunger and the pump spring seat.

[0010] The oil inlet unit includes an oil inlet spring seat, which is a hollow main structure with openings at both ends. The two ends of the oil inlet spring seat are respectively connected to the outlet end of the first oil pipe and the piston cavity. The second steel ball and the oil inlet spring are coaxially connected in the inner cavity of the oil inlet spring seat along the oil passage direction. When the oil inlet spring is in its natural state, the second steel ball is sealed to the inner cavity of the oil inlet spring seat. When the oil inlet spring is compressed, there is space between the second steel ball and the inner cavity of the oil inlet spring seat.

[0011] The oil outlet unit includes an oil outlet spring seat, which is a hollow main structure with openings at both ends. The two ends of the oil outlet spring seat are respectively connected to the inlet end of the second oil pipe and the piston cavity. The first steel ball and the oil outlet spring are coaxially connected in the inner cavity of the oil outlet spring seat along the oil passage direction. When the oil outlet spring is in its natural state, the first steel ball is sealed to the inner cavity of the oil outlet spring seat. When the oil outlet spring is compressed, there is space between the first steel ball and the inner cavity of the oil outlet spring seat.

[0012] Furthermore, it also includes an oil drain channel installed on the main transmission housing. The oil drain channel includes an oil drain groove, a first oil drain passage, and a second oil drain passage connected in sequence. The oil drain groove connects the gap between the second tapered roller bearing and the first tapered roller bearing and the cam. The outlet of the second oil drain passage is connected to the oil sump inside the reducer housing. Moreover, the oil drain groove, the first oil drain passage, and the second oil drain passage are coplanar with the axis of the second tapered roller bearing.

[0013] Furthermore, it also includes a filter that extends into the oil sump inside the reducer housing and connects the inlet end of the first oil pipe to the oil sump inside the reducer housing.

[0014] Preferably, the filter includes a hollow joint extending into the oil sump inside the reducer housing, a cylindrical filter screen coaxially connected to the inner port of the hollow joint, an end cap fastened to the free end of the cylindrical filter screen, and the outer port of the hollow joint connected to the inlet end of the first oil pipe.

[0015] Preferably, the outer periphery of the hollow joint is sealed to the main drive housing by a sealing ring.

[0016] Preferably, the diameter of the third oil inlet passage is smaller than the diameter of the second oil inlet passage.

[0017] Preferably, the first oil inlet passage and the third oil inlet passage are coaxial and perpendicular to the axis of the drive gear.

[0018] Preferably, a hollow bolt is installed between the outlet of the second oil pipe and the inlet of the first oil inlet.

[0019] Compared with the prior art, the advantages of the present invention are:

[0020] (1) The forced lubrication system for the input bearing of the rear axle reducer of an off-road truck, through the reasonable setting of the component structure, completely solves the lubrication problem of the high-position support bearing of the rear axle reducer of the off-road truck, and greatly improves the reliability of the rear axle reducer.

[0021] (2) The forced lubrication system for the input bearing of the rear axle reducer of an off-road truck of the present invention, through the reasonable setting of the component structure, arranges the shortest lubrication path and selects a low-cost one-way piston pump oil pumping assembly while satisfying the forced lubrication function, so that the cost of the reducer assembly can be well controlled.

[0022] (3) The forced lubrication system for the input bearing of the rear axle reducer of an off-road truck of the present invention, through the reasonable setting of the component structure, when the liquid level of the lubricating oil reaches the height of the drain oil groove, the first drain oil passage and the second drain oil passage, the lubricating oil will flow out from the drain oil groove, the first drain oil passage and the second drain oil passage and return to the oil pool in the inner cavity of the reducer, so as to avoid the risk of oil leakage at the oil seal due to long-term operation of the reducer.

[0023] (4) The forced lubrication system for the input bearing of the rear axle reducer of an off-road truck according to the present invention, through the reasonable setting of the component structure, with the reciprocating motion of the plunger, the oil inlet process and the oil outlet process alternate in a cycle, and the lubricating oil circulates in this lubrication circuit, that is, the oil inlet process and the oil outlet process of the control system are controlled.

[0024] (5) The forced lubrication system for the input bearing of the rear axle reducer of an off-road truck of the present invention greatly increases the filtration capacity of the lubricating oil by introducing a filter and the design of the filter structure, ensuring the flow rate of the lubricating oil at the oil inlet, and avoiding the wear of parts such as plungers caused by impurities such as iron filings in the lubricating oil. Attached Figure Description

[0025] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the following detailed description to explain the invention, but do not constitute a limitation thereof. In the drawings:

[0026] Figure 1 This is a right view of the off-road truck rear axle reducer of Example 1;

[0027] Figure 2 for Figure 1 Sectional view of section AA;

[0028] Figure 3 for Figure 2 Sectional view of section BB;

[0029] Figure 4 for Figure 2 A magnified view of a section at point D;

[0030] Figure 5 for Figure 3 A sectional view of section C-C;

[0031] Figure 6 for Figure 2 A cross-sectional view of the filter.

[0032] The labels in the diagram represent:

[0033] 1 Filter, 2 First oil pipe, 3 Inlet spring seat, 4 Pump spring seat, 5 Outlet spring seat, 6 Second oil pipe, 7 Hollow bolt, 8 Main drive housing, 9 Reducer housing, 10 First tapered roller bearing, 11 Cam, 12 Second tapered roller bearing, 13 Drive gear, 14 Bearing cover, 15 Piston, 16 Pump spring, 17 Outlet spring, 18 First steel ball, 19 Inlet spring, 20 Second steel ball, 21 Piston cavity, 22 First inlet oil passage, 23 Second inlet oil passage, 24 Inlet oil groove, 25 Third inlet oil passage, 26 Drain oil groove, 27 First drain oil passage, 28 Second drain oil passage;

[0034] 1-1 Hollow connector, 1-2 Sealing ring, 1-3 Cylindrical filter screen;

[0035] 1-4 end caps, 4-1 limiting shaft. Detailed Implementation

[0036] The invention is not limited to the following specific embodiments. All equivalent modifications made based on the technical solutions of this application fall within the protection scope of this invention.

[0037] It should be noted that the directional terms mentioned herein are consistent with the specific directions on the paper in the accompanying drawings or the corresponding directions of the space shown in the drawings; all components and devices in this invention, unless otherwise specified, are components and devices known in the prior art.

[0038] Example

[0039] This embodiment discloses a forced lubrication system for the input bearing of a rear axle reducer of an off-road truck, including a first oil pipe 2 and a second oil pipe 6 located outside the main drive housing 8 and interconnected with each other. The inlet end of the first oil pipe 2 is connected to the oil sump inside the reducer housing, and a one-way plunger pump assembly is connected between the first oil pipe 2 and the second oil pipe 6. It also includes a first oil inlet passage 22 located inside the main drive housing above the cam 11 and connected to the outlet of the second oil pipe 6. A third oil inlet passage 25 is connected between the outlet of the first oil inlet passage 22 and the gap inside the main drive housing 8 above the cam 11. It also includes a second oil inlet passage 23 located inside the main drive housing 8 above the second tapered roller bearing 12. The inlet end of the second oil inlet passage 23 is connected to the first oil inlet passage 22, and the outlet end of the second oil inlet passage 23 is connected to the high side end of the second tapered roller bearing 12 through an oil inlet groove 24. A gap is left between the end of the oil inlet groove 24 and the bearing cover 14, and the inlet end of the second oil inlet passage 23 is higher than the outlet end of the second oil inlet passage 23.

[0040] Its function is as follows: Under the action of the one-way plunger pump oil assembly, the first oil pipe 2 forcibly draws the oil from the oil sump in the reducer housing and delivers it to the first oil inlet passage 22 through the second oil pipe 6, where it is divided into two paths. One path goes vertically downward through the third oil inlet passage 25 and enters the outer periphery of the cam 11 between the first tapered roller bearing 10 and the second tapered roller bearing 12. The other path goes through the second oil inlet passage 23 and the oil inlet groove 24. At the end of the oil inlet groove 24, the lubricating oil flows through the gap between the end of the oil inlet groove 24 and the bearing cover 14, and then reaches the front end of the second tapered roller bearing 12, thus achieving forced lubrication of the second tapered roller bearing 12. This completely solves the lubrication problem of the high-position support bearing of the rear axle reducer of off-road trucks and greatly improves the reliability of the rear axle reducer.

[0041] In this embodiment, the lubricating oil is divided into two paths at the first oil inlet passage 22. The diameter of the third oil inlet passage 25 is much smaller than the diameter of the second oil inlet passage 23, so the flow rate of the lubricating oil entering from the second oil inlet passage 23 is prioritized to meet the lubrication requirements of the second tapered roller bearing 12. At the same time, part of the lubricating oil on the outer periphery of the cam 11 flows in through the third oil inlet passage 25, and the other part is the lubricating oil flowing into the second tapered roller bearing 12 through the gap of the second tapered roller bearing 12 itself.

[0042] In this embodiment, the first oil inlet channel 22 and the third oil inlet channel 25 are coaxial and perpendicular to the axis of the drive gear 13. The outlet of the second oil pipe 6 is connected to the inlet of the first oil inlet channel 22 by a hollow bolt 7.

[0043] Specifically, the one-way plunger pump oil pumping assembly includes a piston unit that is in mechanical contact with the outer periphery of the cam 11, and also includes an oil inlet unit and an oil outlet unit that are connected to the sealing cavity of the piston unit. The inlet of the oil inlet unit is connected to the outlet end of the first oil pipe 2, and the outlet of the oil outlet unit is connected to the inlet end of the second oil pipe 6.

[0044] Its function is as follows: the rotation of cam 11 drives the piston unit to reciprocate and do work, thereby increasing / decreasing the pressure in the sealed cavity of the piston unit, and through the cooperation of the oil inlet unit and the oil outlet unit, the oil in the oil pool of the reducer box is forcibly extracted.

[0045] The piston unit of this embodiment includes a pump spring seat 4 located outside the main drive housing 8. The pump spring seat 4 has a limiting shaft 4-1 on the side facing the cam 11. A pump spring 16 is coaxially sleeved on the limiting shaft 4-1. A plunger 15 is connected to the free end of the pump spring 16. The plunger 15 is in mechanical contact with the outer periphery of the cam 11, and there is a sealed piston cavity 21 between the plunger 15 and the pump spring seat. The oil inlet unit includes an oil inlet spring seat 3. The oil inlet spring seat 3 is a hollow main structure with openings at both ends. The two ends of the oil inlet spring seat 3 are respectively connected to the outlet end of the first oil pipe 2 and the piston cavity 21. A second steel ball 20 and an oil inlet spring 19 are coaxially connected in the inner cavity of the oil inlet spring seat 3 along the oil passage direction. When the inlet spring 19 is in its natural state, the second steel ball 20 is sealed to the inner cavity of the inlet spring seat 3. When the inlet spring 19 is compressed, there is space between the second steel ball 20 and the inner cavity of the inlet spring seat 3. The oil outlet unit includes an oil outlet spring seat 5, which is a hollow main structure with openings at both ends. The two ends of the oil outlet spring seat 5 are respectively connected to the inlet end of the second oil pipe 6 and the piston cavity 21. The first steel ball 18 and the oil outlet spring 17 are coaxially connected to the inner cavity of the oil outlet spring seat 5 along the oil passage direction. When the oil outlet spring 17 is in its natural state, the first steel ball 18 is sealed to the inner cavity of the oil outlet spring seat 5. When the oil outlet spring 17 is compressed, there is space between the first steel ball 18 and the inner cavity of the oil outlet spring seat 5.

[0046] Oil intake process: Cam 11 moves from high point to low point. Under the action of the pump spring 16, plunger 15 moves from position F to position E. The first steel ball 18 is in position E2 under the action of the oil outlet spring 17 (i.e., the oil outlet spring 17 is in a free state), and the oil outlet is blocked. At this time, because the pressure in the oil sump and the first oil pipe 2 inside the reducer is greater than the pressure in the piston cavity 21 where the plunger 15 and the pump spring seat 4 are located, the oil inlet spring 19 is compressed under the action of the pressure difference. The second steel ball 20 is in position E1 (i.e., the oil inlet spring 19 is in a compressed state), the oil inlet is opened, and the lubricating oil in the first oil pipe 2 enters the piston cavity 21.

[0047] Oil discharge process: Cam 11 moves from low point to high point, plunger 15 moves from position E to position F, pump spring 16 is compressed, second steel ball 20 is in position F1 under the force of inlet spring 19 (i.e., inlet spring 19 is in free state), and oil inlet is blocked; at this time, the pressure in the cavity where pump spring seat 4 and plunger 15 are located is greater than the pressure in the second oil pipe 6 in the inner cavity of outlet spring seat 5. Under the action of pressure difference, outlet spring 17 is compressed, first steel ball 18 is in position F2 (i.e., outlet spring 17 is in compressed state), oil outlet is opened, and lubricating oil in piston cavity 21 enters second oil pipe 6;

[0048] As the plunger 15 reciprocates, the above-mentioned oil inlet and oil outlet processes alternate in a cycle, and the lubricating oil circulates in this lubrication circuit, which is the oil inlet and oil outlet process of the control system.

[0049] In this embodiment, the overall structural design of the piston unit places both the inlet and outlet check valves near the plunger 15, minimizing the oil passage between them. This avoids the problem of difficult air venting caused by a long oil passage, which would result in low or no pumping capacity of the pumping assembly. The entire system utilizes the shortest lubrication path and a low-cost one-way plunger pump assembly, effectively controlling the cost of the reducer assembly.

[0050] In this embodiment, the lubricating oil enters the outer periphery of the cam 11 between the first tapered roller bearing 10 and the second tapered roller bearing 12, and can also achieve lubrication between the cam 11 and the plunger 15.

[0051] This embodiment also includes an oil drain channel arranged on the main transmission housing 8. The oil drain channel includes an oil drain groove 26, a first oil drain passage 27, and a second oil drain passage 28 connected in sequence. The oil drain groove 26 connects the gap between the second tapered roller bearing 12 and the first tapered roller bearing 10 and the cam 11. The outlet of the second oil drain passage 28 is connected to the oil sump inside the reducer housing. The oil drain groove 26, the first oil drain passage 27, and the second oil drain passage 28 are coplanar with the axis of the second tapered roller bearing 12.

[0052] Its function is as follows: As lubricating oil flows in continuously, a large amount of lubricating oil will accumulate in the front section of the second tapered roller bearing 12. Long-term operation of the reducer will increase the risk of oil leakage at the oil seal. Therefore, through the cooperation of the drain oil groove 26, the first drain oil passage 27 and the second drain oil passage 28, when the level of the lubricating oil reaches the height of the drain oil groove 26, the first drain oil passage 27 and the second drain oil passage 28, the lubricating oil will flow out from the drain oil groove 26, the first drain oil passage 27 and the second drain oil passage 28 and return to the oil sump in the inner cavity of the reducer.

[0053] This embodiment also includes a filter 1 that extends into the oil sump inside the reducer housing and connects the inlet end of the first oil pipe 2 to the oil sump inside the reducer housing; the filter 1 includes a hollow joint 1-1 that extends into the oil sump inside the reducer housing, the outer periphery of the hollow joint 1-1 is sealed to the main drive housing 8 by a sealing ring 1-2, a cylindrical filter screen 1-3 is coaxially connected to the inner port of the hollow joint 1-1, an end cap 1-4 is fastened to the free end of the cylindrical filter screen 1-3, and the outer port of the hollow joint 1-1 is connected to the inlet end of the first oil pipe 2;

[0054] The entire system, especially the one-way plunger pump oil assembly, has high requirements for the cleanliness of the lubricating oil. In order to avoid impurities such as iron filings in the lubricating oil from accelerating the wear of parts such as the plunger, and to ensure sufficient lubricating oil flow at the oil inlet, this embodiment introduces a filter 1. The entire cylindrical filter screen 1-3 is arranged along the circumference and the length of the cylindrical filter screen 1-3 is at least half the length of the entire filter 1. This greatly increases the filtration capacity of the lubricating oil and ensures the lubricating oil flow at the oil inlet.

[0055] The preferred embodiments of this disclosure have been described in detail above with reference to the accompanying drawings. However, this disclosure is not limited to the specific details of the above embodiments. Within the scope of the technical concept of this disclosure, various simple modifications can be made to the technical solutions of this disclosure, and these simple modifications all fall within the protection scope of this disclosure.

[0056] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, this disclosure will not describe the various possible combinations separately.

[0057] Furthermore, the various implementation methods disclosed in this solution can be combined in any way, as long as they do not violate the spirit of this disclosure, they should also be regarded as the content invented by this disclosure.

Claims

1. A forced lubrication system for the input bearing of a rear axle reducer in an off-road truck, wherein a first tapered roller bearing (10), a cam (11), and a second tapered roller bearing (12) are assembled on a drive gear (13), the central axis of the drive gear (13) forming a certain angle of elevation with the horizontal direction, characterized in that, It includes a first oil pipe (2) and a second oil pipe (6) located outside the main transmission housing (8) and connected to each other. The inlet end of the first oil pipe (2) is connected to the oil sump inside the reducer housing. A one-way plunger pump assembly is connected between the first oil pipe (2) and the second oil pipe (6). It also includes a first oil inlet passage (22) located in the main drive housing above the cam (11) and connected to the outlet of the second oil pipe (6), and a third oil inlet passage (25) connected between the outlet of the first oil inlet passage (22) and the gap in the main drive housing (8) above the cam (11). It also includes a second oil inlet passage (23) located in the main drive housing (8) above the second tapered roller bearing (12). The inlet end of the second oil inlet passage (23) is connected to the first oil inlet passage (22), and the outlet end of the second oil inlet passage (23) is connected to the high side end of the second tapered roller bearing (12) through an oil inlet groove (24). A gap is left between the end of the oil inlet groove (24) and the bearing cover (14). The inlet end of the second oil inlet passage (23) is higher than the outlet end of the second oil inlet passage (23).

2. The forced lubrication system for the input bearing of the rear axle reducer of an off-road truck as described in claim 1, characterized in that, The one-way plunger pump oil pumping assembly includes a piston unit that is in mechanical contact with the outer periphery of the cam (11), and also includes an oil inlet unit and an oil outlet unit that are connected to the sealing cavity of the piston unit. The inlet of the oil inlet unit is connected to the outlet end of the first oil pipe (2), and the outlet of the oil outlet unit is connected to the inlet end of the second oil pipe (6).

3. The forced lubrication system for the input bearing of the rear axle reducer of an off-road truck as described in claim 2, characterized in that, The piston unit includes a pump spring seat (4) located outside the main drive housing (8). The pump spring seat (4) has a limiting shaft (4-1) on the side facing the cam (11). A pump spring (16) is coaxially sleeved on the limiting shaft (4-1). A plunger (15) is connected to the free end of the pump spring (16). The plunger (15) is in mechanical contact with the outer periphery of the cam (11), and there is a closed piston cavity (21) between the plunger (15) and the pump spring seat. The oil inlet unit includes an oil inlet spring seat (3), which is a hollow main structure with openings at both ends. The two ends of the oil inlet spring seat (3) are connected to the outlet end of the first oil pipe (2) and the piston cavity (21) respectively. The inner cavity of the oil inlet spring seat (3) is coaxially connected with the second steel ball (20) and the oil inlet spring (19) along the oil passage direction. When the oil inlet spring (19) is in its natural state, the second steel ball (20) is sealed with the inner cavity of the oil inlet spring seat (3). When the oil inlet spring (19) is compressed, there is space between the second steel ball (20) and the inner cavity of the oil inlet spring seat (3). The oil outlet unit includes an oil outlet spring seat (5), which is a hollow main structure with openings at both ends. The two ends of the oil outlet spring seat (5) are connected to the inlet end of the second oil pipe (6) and the piston cavity (21) respectively. The inner cavity of the oil outlet spring seat (5) is coaxially connected with the first steel ball (18) and the oil outlet spring (17) along the oil passage direction. When the oil outlet spring (17) is in its natural state, the first steel ball (18) is sealed with the inner cavity of the oil outlet spring seat (5). When the oil outlet spring (17) is compressed, there is space between the first steel ball (18) and the inner cavity of the oil outlet spring seat (5).

4. The forced lubrication system for the input bearing of the rear axle reducer of an off-road truck as described in any one of claims 1-3, characterized in that, It also includes an oil drain channel arranged on the main transmission housing (8). The oil drain channel includes an oil drain groove (26), a first oil drain channel (27), and a second oil drain channel (28) connected in sequence. The oil drain groove (26) connects the gap between the second tapered roller bearing (12), the first tapered roller bearing (10), and the cam (11). The outlet of the second oil drain channel (28) is connected to the oil sump inside the reducer housing. The oil drain groove (26), the first oil drain channel (27), and the second oil drain channel (28) are coplanar with the axis of the second tapered roller bearing (12).

5. The forced lubrication system for the input bearing of the rear axle reducer of an off-road truck as described in claim 4, characterized in that, It also includes a filter (1) that extends into the oil sump inside the reducer housing and connects the inlet end of the first oil pipe (2) to the oil sump inside the reducer housing.

6. The forced lubrication system for the input bearing of the off-road truck rear axle reducer as described in claim 5, characterized in that, The filter (1) includes a hollow joint (1-1) that extends into the oil sump inside the reducer housing. A cylindrical filter screen (1-3) is coaxially connected to the inner port of the hollow joint (1-1). An end cap (1-4) is fastened to the free end of the cylindrical filter screen (1-3). The outer port of the hollow joint (1-1) is connected to the inlet end of the first oil pipe (2).

7. The forced lubrication system for the input bearing of the off-road truck rear axle reducer as described in claim 6, characterized in that, The hollow joint (1-1) is sealed to the main drive housing (8) by a sealing ring (1-2).

8. The forced lubrication system for the input bearing of the rear axle reducer of an off-road truck as described in claim 1, characterized in that, The diameter of the third oil inlet channel (25) is smaller than the diameter of the second oil inlet channel (23).

9. The forced lubrication system for the input bearing of the rear axle reducer of an off-road truck as described in claim 1, characterized in that, The first oil inlet passage (22) and the third oil inlet passage (25) are coaxial and perpendicular to the axis of the drive gear (13).

10. The forced lubrication system for the input bearing of the rear axle reducer of an off-road truck as described in claim 1, characterized in that, A hollow bolt (7) is installed between the outlet of the second oil pipe (6) and the inlet of the first oil inlet channel (22).

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