Features of QJM Hydraulic Motor

The QJM series hydraulic motor can be matched with various oil pumps, valves, and hydraulic accessories to form a hydraulic rotation device, which is adaptable to a wide range of mechanical operating conditions. This hydraulic motor has a series of advantages, including light weight, compact size, wide speed regulation range, excellent low-speed stability, reliable operation, impact resistance, high efficiency, and long service life. Its main features are as follows:

The rolling element of this motor uses a single steel ball instead of the two or more rollers and crossbeams used in conventional internal-curve hydraulic motors. As a result, it features a simple structure, reliable operation, compact size, and light weight.

With a small moment of inertia and robust, reliable steel balls, the motor can operate continuously under impact loads.

It has low friction: the oil distribution shaft and rotor achieve internal balance; the ball-plunger pair transmits force through a ball pad made of self-lubricating composite material, with hydrostatic balance and good lubrication conditions. A soft plastic piston ring that automatically compensates for wear is used to seal high-pressure oil. Therefore, the motor has high mechanical and volumetric efficiency, can operate stably at extremely low speeds, and delivers a large starting torque.

Due to its structural characteristics, the motor requires relatively low return oil backpressure, generally ranging from 0.3 MPa to 0.8 MPa. The higher the rotational speed, the greater the required backpressure.

This motor is equipped with two-speed and three-speed displacement control, thus providing a wide speed regulation range.

It has a simple structure, enabling easy disassembly and maintenance. There are no special requirements for oil cleanliness, and the oil filtration precision can be selected according to the requirements of the matched oil pump.

Translation of Text on Slewing Reducers and Related Maintenance

If the center distance between the slewing reducer of lifting equipment and the slewing bearing decreases, how should the slewing reducer be adjusted? This requires checking for issues with the slewing bearing or problems caused by gear wear. If the problem is not with the gears, it means the raceway of the slewing bearing is worn—this increases the backlash of the slewing bearing and impairs slewing performance. In such cases, repair the raceway as soon as possible or replace the slewing bearing.

When abnormal noise occurs in the slewing reducer of an excavator, it may be due to the low viscosity of the hydraulic oil in the excavator’s slewing reducer (which causes abnormal sounds). The possibility of issues related to the hydraulic system itself is very low. Check whether there are metal debris in the gear oil and verify the grease filling condition of the motor reducer.

If the gear oil in the excavator’s slewing reducer cannot be drained completely: Generally, the slewing reducer housing of a hydraulic cycloid motor holds a maximum of a little more than one barrel of gear oil. If the oil volume is excessive, it indicates that hydraulic oil is leaking into the reducer. When you add oil, pull out the oil dipstick at the same time—this allows air to enter and speeds up the oil filling process. You can also use a tool to clear the oil filling port to check for blockages. There is no need to change the gear oil too frequently; changing it every 2,000 operating hours is acceptable.