Created on:2021-05-07 08:47

Fault diagnosis and elimination of internal components damage of inclined shaft variable axial piston motor

Fault diagnosis and elimination of internal components damage of inclined shaft variable axial piston motor

① Several Komatsu pc400-3 hydraulic excavators are driven by inclined axial piston variable motor. Figure K is the structural diagram of the motor, which is composed of the housing 1, the cylinder block 2, the plunger 9, the port plate 12, the central shaft 13, the output shaft 6, and the parking brake (including the brake box 7, the brake piston 3, the internal and external tooth brake discs 5 and 4, and the brake spring 10, etc.). The brake is spring up brake and hydraulic release brake structure, that is, when the machine does not move, the motor provides pressure oil, which is always in the up brake state under the elastic force of brake spring 10; when the machine moves, the high pressure oil entering the motor pushes the brake piston 3, releases the brake, and the motor brake is released.

K1.jpg

Several excavators only used 3450 hours, the walking motor appeared to release the brake slowly, brake piston oil seal aging, brake disc internal and external teeth internal parts damaged, plunger, cylinder and other internal parts seriously damaged.

② Cause analysis: because several excavators are operating in the south, the environmental temperature is high, and the heat dissipation performance of the machine itself is not enough to ensure sufficient heat exchange, resulting in the high temperature of the hydraulic oil, resulting in the aging and damage of the oil seal on the brake piston 3, resulting in the decline of its sealing capacity. The resulting internal leakage makes the volumetric efficiency and mechanical efficiency of the motor brake piston cylinder vary Down. The decrease of volumetric efficiency will directly lead to the decrease of the movement speed of the brake piston and the extension of the time required to release the brake. In addition, the hydraulic thrust of the brake piston will also be reduced due to the reduction of mechanical efficiency (greater pressure loss). When the hydraulic motor starts to work to drive the machine to walk, because the brake is released slowly, and the hydraulic thrust of the brake piston is reduced, while the elastic force of the brake spring 10 remains unchanged, the brake can not be released completely, resulting in the machine walking fatigue, resulting in friction and wear between the brake discs. In addition, the internal teeth of the internal tooth brake disc 4 and the disc gear part of the motor output shaft 6 produce relative motion; the external teeth of the external tooth brake disc 4 and the internal teeth part of the motor housing also produce relative motion. In this way, the inner and outer teeth on the inner and outer brake discs will have abnormal wear and impact, and the inner and outer teeth will be damaged after a long time of operation. The metal particles and debris produced by wear or damage will enter into the plunger, cylinder block and slide valve of the motor, causing serious damage to these parts. At the same time, the heat generated by friction will further increase the oil temperature and aggravate the damage of the motor.

③ The oil seal of the brake piston of the hydraulic motor is replaced every 2000h. Since this measure was taken, several Komatsu hydraulic excavators have been used for nearly 10000h, and the above faults have not occurred again. In addition, the cooler should be replaced on time according to the technical requirements of the motor, and the hydraulic oil should be used to ensure the normal working effect.

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