Repair of Abnormal noise Fault of the rear axle differential of XCMG ZL50 Loader

Fault phenomenon: A ZL50 model loader produced by XCMG was operating in the field. When traveling in a straight line, the sound of the rear drive axle was normal, but when turning, the sound was abnormal.

Troubleshooting: Based on the initial judgment of the fault phenomenon, the fault may occur in the rear drive axle differential. When a loader travels in a straight line, the wheels on both sides roll the same distance at the same time. At this time, the differential housing rotates together, and at this time, the differential does not function as a differential. When the loader turns and travels, the planetary gears not only drive the two half shaft gears to rotate but also rotate around the cross journal. Due to the different resistance exerted by the wheels on both sides on the planetary gears, the rotational speeds of the two half shafts are unequal. At this time, the differential plays a differential role. Therefore, it is judged that the fault may occur in the differential.

Remove the connecting screws between the rear drive axle and the frame, the screws of the main transmission disc, and the oil pipe joints of the brake, etc. Use a crane to lift the frame and push the rear drive axle backward. The gear oil in the rear drive axle and the wheel side reducers on both sides was drained. It was found that the gear oil in the rear drive axle was too dirty, with some needle-like and flaky metal debris in the oil.

Disassemble the drive axle housing to remove the main transmission, differential, two half shafts and the sun gears of the two wheel-mounted reducers. After disassembling the differential housing, it was found that the four planetary gears and two half shaft gears and wheels inside the differential were severely damaged. Of the four planetary gears, only one gasket remains relatively intact, while the rest have all been worn out. The driving bevel gear, cross shaft and differential housing are severely worn, and there are many large and small needle-like and flaky metal debris at the bottom of the drive axle housing.

When analyzing the cause of the fault, the operator was consulted and other working devices were inspected. It turns out that this loader is driven by both front and rear axles (four-wheel drive), which makes it difficult to engage and, once engaged, hard to separate. The operator has never checked the gear oil in the drive axle again. Due to the excessively dirty gear oil in the rear drive axle, the gaskets of the planetary gears wore out, resulting in an increase in the clearance between the planetary gears and the two half shaft gears. Moreover, during fieldwork, the terrain is uneven and full-load turning operations are often carried out, which causes the teeth of the planetary gears and the two half shaft gears to be damaged due to excessive clearance during high-speed rotation. The damaged metal debris enters the bottom of the rear drive axle and the gear oil, causing severe wear to the driving bevel gear, cross shaft and differential housing during rotation. However, when traveling in a straight line, the four planetary gears and two half shaft gears inside the differential revolve along with the differential without rotating on their own axes, so the rear drive axle makes no noise. When turning and driving, the four planetary gears meshing with the two half shaft gears start to rotate on their own due to the unequal resistance they encounter. Also, because of the excessive clearance between them and the damage of the meshing teeth, a "click, click" noise is produced. The more severe the damage, the greater the noise.

So, the rear drive axle housing and other parts were cleaned thoroughly, the differential and main transmission were replaced, and two half shafts, the sun gears of two wheel-side reducers and the drive axle housing were reinstalled. New gear oil has been added to the rear drive axle and two wheel-side reducers. Lift the frame with a crane and install the drive axle and wheels in place. After assembly, the drive axle is connected to the frame, main transmission and brake, etc. Troubleshooting.