Troubleshooting the fault of weak rotation of excavators

The W4-60 excavator needs to be repaired due to weak rotation during use. Firstly, the system oil pressure and the connection conditions of each valve (control valve group, etc.) and oil pipe were inspected. No abnormal phenomena were found. Finally, it was confirmed that it might be caused by severe wear of the hydraulic motor plunger leading to internal leakage. Therefore, when the motor was removed for disassembly inspection, it was found that the elasticity of the piston rings was relatively weak, and there was a loose feeling after the plunger was installed. After measurement and inspection, it was found that the plunger was worn. So, when a new plunger was replaced and reassembled for testing, it was found that not only did the rotational torque not increase, but the entire machine body also trembled when the boom was turned, and there seemed to be a foreign object stuck between the gear ring and the transmission gear.

Therefore, the motor was disassembled again and reassembled. After inspection, it was found that: In the plunger assembly, if the guide sleeve is reversed, when the plunger cylinder rotates, due to the elastic contact of the spring, it cannot drive the lower cover to rotate synchronously. Therefore, the high-pressure oil cannot be distributed to the adjacent several plungers as required, causing the oil intake of the plungers to be disordered. This forms an impact torque in the motor, and during the rotation of the boom, there will be a "shaking" phenomenon of weak work, sudden rotation and stop, and sudden speed and slow. When installing a hydraulic motor, the following points must be noted:

When installing the motor cover, special attention should be paid to ensuring that the two oil ports on the cover are located in the middle symmetrical position on both sides of the line connecting the highest and lowest points of the swash plate. Otherwise, individual plungers will generate negative torque, causing the motor to rotate weakly or even not at all. When determining the highest (lowest) point, after installing a plunger in the cylinder (without other components), press the upper part of a certain plunger with your hand to keep it always tightly against the swash plate surface. Then, rotate the plunger cylinder. When the plunger moves up (down) to the area near the highest (lowest) point, slowly rotate the Atlas air compressor parts. Find the highest (lowest) point of the upper (lower) row of the plunger and the corresponding point of this plunger, which is the highest (lowest) point of the swash plate. Connect this highest and lowest point with a ruler and draw the perpendicular bisector of this straight line to intersect two points on the motor housing. Mark them on both sides of the housing. Align these marks with the centers of the inlet and return oil pipe joints of the upper cover. Finally, install the bolts in sequence. Once the upper cover of the motor is fixed, the assembly is completed.