Performance Testing and Overhaul of Hydraulic Cylinders

Performance Test Items

1. reversing smoothness: reversing valve should be smooth when reversing, reversing impact should not exceed the specified value or meet the requirements of use.
2. reversing time and reset time: reversing valve main spool reversing time should be flexible, reset quickly, reversing pressure and reversing time adjustment performance must be good.
3. Pressure loss: In passing the rated flow, the pressure loss shall not exceed the specified value.
4. Leakage: at rated pressure, the amount of leakage shall not exceed the specified value, while in the valve cover and other places are not allowed to have leakage.
5. Check valve to do open pressure test, the value shall not exceed the specified value.

Flow Control Valve Maintenance Points

1. Disassemble the flow control valve to check the scarring and wear of the throttle port.
2. Check the corresponding position of throttle and scale.
3. Check the state of the pressure compensation valve spool.
4. Replace the seals, springs and damaged parts that are not suitable for repair.
5. Remove the rust spots and burrs of each part to make it meet the requirements, then carefully clean each part and oil it for assembly, and strictly prevent dirt from mixing into the throttle, pay attention to the installation position of the throttle part, and confirm the normal action after installation.

Performance Test Items

1. Adjustment flow characteristics: in the minimum flow to the maximum flow range can be flexible and reliable adjustment, and the flow value is stable.
2. Stability: for the speed control valve to adjust the throttle to the minimum opening, measure the stability of the flow through the speed control valve, the change in value should not exceed the specified requirements.
3. Leakage: measure the amount of internal leakage at rated pressure. Its value is not allowed to exceed the specified value, while in the valve cover and other places do not allow external leakage phenomenon.

Hydraulic Cylinder Maintenance Points

1. Disassemble the hydraulic cylinder to check the internal and piston rod surface scars, wear and tear of the hydraulic cylinder.
2. Check the installation status of the piston seal, the tightness of the installation screw and the damage of the seal and the reason.
3. Check the rust and pollutant adhesion status of all internal parts of the cylinder.
4. Replace the seals, dustproof parts and other parts that are not suitable for repair.

Performance Test Items

1. Smoothness of movement: Under no load, the full stroke reciprocating movement test of the hydraulic cylinder, reciprocating action for more than 5 times, should achieve normal and smooth movement.
2. Minimum starting pressure: under no-load condition, pass pressure oil to the rodless chamber of the cylinder under test, gradually pressurize and record the minimum starting pressure when the piston rod starts, the minimum starting pressure is required to meet the relevant quality regulations.
3. Minimum stable speed: the minimum speed of the hydraulic cylinder is required to move without "crawling" and other abnormal phenomena.
4. Internal leakage: under the rated pressure, the leakage from the high pressure chamber to the low pressure chamber through the seal is in accordance with the relevant quality classification regulations.
5. External leakage: under full load conditions, the full stroke change of direction more than 20 times, the piston rod and the combined surface shall not have external leakage.
6. pressure test: the test hydraulic cylinder rated pressure ≤ 16Mpa, the test pressure is 1.5 times its rated pressure, holding pressure 1-5min; the test hydraulic cylinder rated pressure ≥ 16Mpa, the test pressure is 1.25 times its rated pressure, holding pressure 2-5min. all parts shall not be damaged plastic change and other abnormal phenomena.
7. Buffer performance: the hydraulic cylinder with a buffer device to carry out buffer performance test. Test the highest speed reciprocating motion according to the design requirements, observe the buffer effect, and should meet the design requirements or use requirements.
8. Full stroke check: make the piston of the hydraulic cylinder under test stay in the position of both ends of the stroke, measure the full stroke length, the value of which meets the design requirements.

The overhaul of hydraulic components is to improve efficiency, extend service life, no or less failure, and reduce maintenance costs for the purpose of the operating process. Only the correct overhaul of hydraulic components can ensure reliable operation, good performance and maximize the benefits.