Hydraulic Motor Maintenance Methods

As a core actuator in hydraulic systems, hydraulic motors effectively convert the liquid pressure energy provided by hydraulic pumps into mechanical energy (torque and rotational speed). However, failures in this component can lead to oil leakage, reduced speed, increased noise, excessive vibration, overheating, and sluggish operation. Addressing these issues is critical. This article will discuss these challenges in detail.

Hydraulic motors, commonly referred to as oil motors, are key components in hydraulic systems. Their primary function is to convert the liquid pressure delivered by hydraulic pumps into mechanical energy at the output shaft. Due to their compact size, lightweight design, simple structure, and excellent resistance to oil contamination, these devices are widely used in injection molding machines, marine machinery, construction equipment, and other fields.

From a classification perspective, hydraulic motors can be categorized by structural type, rated speed, and operating mode. Common types include radial piston motors, axial piston motors, and oscillating cylinder motors. Different motor models also vary in fault diagnosis methods and criteria. This article will focus on the "cycloidal motor"—a type commonly used in construction and marine machinery.

The cycloidal motor is a low-speed, high-torque hydraulic motor. Its internal structure consists of an internally meshing cycloidal pin-gear planetary transmission mechanism. By utilizing a unique tooth difference principle, it effectively integrates the functions of a high-speed hydraulic motor and a reduction gearbox.

In practical applications, hydraulic motors inevitably encounter failures due to their complex working environments. Key failure-prone components include the distribution shaft, valve plate, rotor, and stator. Common issues include wear on the valve plate, tooth surface wear on the rotor and stator, and oil seal damage. Below, we discuss three common failure types and their repair methods.

Maintenance Experience Sharing

1. Motor Weakness During Operation

1. Check the clearance between the stator and rotor. Substandard hydraulic oil quality accelerates part wear, leading to internal leakage. Symptoms include normal operation under no load but weakness under load. Solution: Replace with appropriately sized needle teeth.

2. Inspect the contact between the output shaft and the housing bore. Severe wear here can also cause internal leakage. Replace damaged components promptly.

2. Unstable Operation at Low Speeds

1. Examine the tooth surface wear on the rotor. Worn areas increase friction, causing speed and torque fluctuations. Solution: Replace the rotor and stator with components of reduced tooth contact pressure to improve low-speed performance.

2. Ensure free rotation of the needle wheel inside the stator. Adjust its thickness slightly to maintain smooth operation at low speeds.

   
   

3. Reduced Speed and Insufficient Output Torque

1. For cycloidal motors without gap compensation: Wear on the rotor-stator contact surfaces leads to internal leakage, directly affecting speed and volumetric efficiency. Solution: Replace worn parts immediately.

2. Check alignment between the distribution shaft and the motor body. Misalignment significantly reduces speed and torque. Ensure precise positional matching.

3. Repair worn distribution shafts. Use electroplating or brush plating to restore working clearance accuracy and effectiveness.

By following these methods, engineers can systematically diagnose and address common hydraulic motor failures, ensuring optimal performance and longevity of the equipment.