FAQ

Unstable speed may be caused by many factors: First, the oil supply pressure is insufficient or unstable. It is necessary to check the working status of the axial piston pump and the system pressure setting. Secondly, the internal leakage of the motor is too large, especially the wear between the valve plate and the cylinder body will lead to a decrease in volumetric efficiency. The matching surface should be checked and the worn parts should be repaired or replaced. Improper adjustment of the variable mechanism can also cause unstable output, and the variable mechanism needs to be recalibrated. Hydraulic oil viscosity is too low or the oil temperature is too high, which will increase internal leakage. The appropriate viscosity oil should be selected and the cooling system should be checked. Excessive external load fluctuations will also affect the speed stability. It is necessary to check whether there are any abnormalities in the load connection parts.

Failure of the variable mechanism may manifest as an inability to adjust the flow or unstable adjustment. First check whether the control oil circuit is blocked. If necessary, flush the system and replace the clean oil. Wear of the variable head and variable body will lead to inaccurate control and need to be scraped and repaired. When the servo valve core, differential piston or spring core shaft is stuck, if it is mechanically stuck, you can try to grind and repair it. If it is due to oil contamination, the oil should be replaced and the system should be cleaned. For electronically controlled variable pumps, it is also necessary to check whether the electrical signal and control circuit are normal. During regular maintenance, special attention should be paid to the lubrication and cleaning of the variable mechanism to prevent impurities from entering the precision matching surface.

Excessive oil temperature is usually caused by the following reasons: Excessive internal leakage will convert hydraulic energy into heat energy, and the worn parts such as the oil distribution plate and plunger need to be checked and repaired. Setting the system pressure too high or overloading for a long time will increase energy loss, and the pressure valve setting value should be adjusted reasonably. When the cooling system is inefficient or the heat dissipation area is insufficient, it is necessary to check the working status of the cooler or increase the heat dissipation capacity. The increase in back pressure caused by blockage of the return oil filter will also cause temperature rise, and the filter element should be replaced regularly. The key measures to control oil temperature include: keeping the system well sealed to reduce internal leakage, setting the working pressure reasonably, ensuring the normal operation of the cooling system, and regularly maintaining the filtration system.

There are several factors to consider when choosing hydraulic oil: First, determine the operating temperature range of the oil tank according to the ambient temperature, and ensure that the oil viscosity is in the optimal range (nopt) at the operating temperature. It is usually recommended to choose a higher viscosity grade. For example, at an operating temperature of 60°C, VG68 should be preferred when both VG46 and VG68 are applicable. The oil cleanliness should be at least 20/18/15 grade of ISO4406 standard, and 19/17/14 grade under high temperature conditions (90-115°C). For special applications such as those with high environmental requirements, refer to the guidance of technical parameter tables RC90220 (mineral oil), RC90221 (ecological oil) and RC90223 (HF oil). At the same time, pay attention to the compatibility of the oil with the system sealing material, and avoid using expired or recycled oil.

Insufficient or fluctuating pressure may be caused by a variety of factors: Severe wear between the oil distribution plate and the cylinder body or between the plunger and the cylinder body will lead to increased internal leakage. At this time, it is necessary to check and repair the mating surface, and replace the plunger if necessary. For variable pumps, if the variable mechanism angle is set too small, it will cause insufficient flow. The variable angle should be appropriately increased. Blockage or leakage in the oil inlet pipe will also cause unstable pressure. It is necessary to dredge the pipe, clean the filter and tighten the connection. Fatigue or breakage of the center spring will cause insufficient return of the plunger, affecting the sealing performance, and the spring must be replaced. Excessive oil temperature will cause a decrease in viscosity, which will increase internal leakage. The cooling system should be checked and the oil of appropriate viscosity should be selected.

The reasons why axial piston pumps are too noisy usually include the following aspects: First, there may be air inside the pump, which is common in newly installed pumps or after system maintenance. The solution is to open the refueling port when the pump is running to exhaust the internal air. Secondly, if the oil level in the oil tank is too low or the suction pipe is blocked, it will increase the oil suction resistance, causing the pump to suck empty and produce noise. The oil level should be checked and hydraulic oil should be added as needed, and the filter should be cleaned or replaced. Third, if the oil pump and the motor are not installed concentrically, the pump shaft will be subjected to additional radial force and produce noise. The concentricity needs to be readjusted to the tolerance range. In addition, too high viscosity of hydraulic oil will also increase the self-priming resistance of the pump. The appropriate viscosity grade should be selected according to the ambient temperature, and the heater should be used to preheat the oil when necessary.