Observe the cylinder for physical damage or external fluid leakage. Check the piston actuator for bends, gouges, pits, cracks or other defects that may indicate a mechanical problem with the machinery. Repair or replace the cylinder if it is damaged. Locate and repair the cause of the cylinder damage and correct it as required.
Start the machinery and pressurize the hydraulic system. Do not actuate the cylinder circuit. Listen at the body of the cylinder for an internal hissing noise. If a hissing noise is present, then the cylinder is leaking internally and must be repaired or replaced.
Shut down the machine and allow the fluid pressure to dissipate. Disconnect the fluid supply line or lines at the cylinder. Cap off the cylinder ports using the correct JIC caps. Attach a 5,000 psi gauge to the supply hose or hoses using the correct adapters.
Start the machinery and actuate the control circuit of the cylinder. Observe the reading on the gauge or gauges and compare the reading to the machine drawings. With the supply hose capped off with the gauge, no fluid movement is allowed and the pressure on the gauge should read the maximum allowable in the circuit. If the gauge reading is significantly less than the operating pressure of the equipment, then the cylinder is not at fault. Repair, adjust or replace any component as required to bring the operating pressure up to specifications.
Shut down the machinery and allow the hydraulic pressure to dissipate. Remove the pressure gauge or gauges, all adapters, caps or plugs. Attach the supply hose or hoses to the cylinder. Disconnect the actuator side of the cylinder from the equipment and allow the end of the cylinder to hang free. Start the machinery and actuate the cylinder. If the cylinder does not operate smoothly, or if it fails to extend fully, then the cylinder is defective and must be replaced.
Reconnect the actuator side of the cylinder to the machinery. If the pressure readings from Step 4 are correct and the cylinder is not leaking internally, externally or has physical damage, then the cylinder is operating correctly. If the machinery is still not working properly at this point, then the problem is with the mechanical components of the equipment and not the actuating cylinder.