What Should Be Done If The Custom Hydraulic System Operates Slowly Or at A Reduced Speed?

What should be done if the custom hydraulic system operates slowly or at a reduced speed?

1.The adverse effects of insufficient speed of the hydraulic pump

The under-speed of the hydraulic pump actuating elements (hydraulic cylinders and hydraulic motors) includes two situations:

One issue is that when performing rapid movement (fast-forward), the speed is not fast enough and fails to reach the designed value and the specified value of the new hydraulic pump.

Second, under load, its working speed (traveling speed) significantly decreases as the load increases. Especially for large hydraulic pumps and those with heavy loads, this phenomenon is particularly pronounced. The speed is generally related to the flow rate.

Under-speeding first affects production efficiency, increasing the cycling working time of the hydraulic pump; the under-speeding phenomenon often leads to a situation where the hydraulic pump stops moving under heavy loads, which will affect its normal operation. For hydraulic pumps that require rapid movement, such as those in planar grinding machines, insufficient speed will affect the roughness of the grinding surface.

2. Causes of under-speed failure

1) Reasons for insufficient speed of rapid movement

This is a common fault in the maintenance of hydraulic pumps. It can occur due to several factors.

The output flow of the hydraulic pump is insufficient and the output pressure fails to meet the requirements.

② The overflow valve may malfunction due to spring deformation or improper installation as a weak spring. Additionally, if the damping hole of the main valve core is partially blocked or the main valve core gets stuck at a small opening position, the pressure oil output by the hydraulic pump will partially flow back to the oil tank. As a result, the effective flow rate supplied to the actuating elements will significantly decrease, causing the speed of rapid movement to be insufficient.

③ Severe internal and external leakage in the system: During rapid movement, the working pressure is generally low, but it is much higher than the pressure in the return oil circuit. When the piston seal of the hydraulic cylinder is damaged, due to the leakage of the two chambers through the crossover (with a pressure difference), there is a significant internal leakage in both chambers of the hydraulic cylinder, resulting in insufficient rapid movement speed of the hydraulic cylinder, as well as internal and external leakage in other parts.

④ When in fast forward mode, the resistance is high. This may be due to reasons such as the loss of lubrication in the guide rail, the overly tight fit of the insert plate and the bearing plate of the guide rail, or poor installation accuracy and assembly accuracy of the hydraulic cylinder, which all contribute to an increase in the frictional resistance during fast forward movement.

2) Reasons for the significant decrease in feed rate during operation

During work feed, the feed speed significantly decreases under load. Even if the speed control valve (such as a throttle valve) is opened wider, the same phenomenon occurs. Therefore, an analysis and repair should be conducted from the following aspects.

When the system is under load, the working pressure increases and the leakage also rises. As a result, the adjusted speed decreases due to the increase in internal and external leakage.

② The system oil temperature rises, the oil viscosity decreases, leakage increases, and the effective flow rate reduces.

③ The design of the hydraulic system is unreasonable. When the load changes, the flow rate entering the actuating elements of the hydraulic equipment also changes, resulting in a change in speed.

④ The oil contains impurities, which clog the throttling orifice of the flow regulating valve, resulting in a decrease in the working speed; at times blocked and at times unblocked, causing unstable speed.

⑤ There is air in the hydraulic system.

3. Methods for eliminati 2. Causes of under-speed failure ng under-speed conditions

1) Eliminate the faults of insufficient output flow and low output pressure from the hydraulic oil pump.

2) Eliminate faults caused by pressure valves such as relief valves that prevent the pressure from rising.

3) Locate the positions causing internal and external leaks, eliminate the leaks, replace the severely worn parts to eliminate the internal leaks.

4) Control the oil temperature.

5) Clean parts such as the flow valve. If the oil is severely contaminated, replace the oil promptly.

6) Identify the cause of the air intake in the hydraulic system and remove the air from the hydraulic system.

4. Hydraulic System Maintenance Suggestions

1) Maintain the normal oil level. An oil level indicator should be installed in the oil tank to facilitate regular observation and oil replenishment.

2) It is necessary to regularly check the performance of the oil. If it fails to meet the specified requirements, it should be replaced immediately and the oil tank should be cleaned.

3) The oil filter should be cleaned frequently to ensure smooth intake of the oil.

4) After the oil pump has been operating for a period of time, (due to vibration), the installation screws or the screws of the inlet and outlet oil valves may become loose. It is necessary to pay attention to checking and tightening them with anti-loosening measures.

5) The hydraulic impact force of the system must not exceed 14 Mpa.

6) To carry out the maintenance of the system properly, it is necessary to understand the relationship between the working temperature of the oil in the oil tank (for open circuits) and the ambient temperature. The temperature at any point in the system must not exceed 90 degrees.