Cylinder Testing…

A key element of troubleshooting your hydraulic system is testing the cylinders. Following these steps on a regular basis will help keep your hydraulics in working order, as well as identify when you need hydraulic repair.

Run the piston to one end of its stroke where the cylinder is stalled. Remove the line to the cylinder on the same end as the piston is stalled. Install a pressure gauge in this port and plug the open line. With the line plug and gauge installed, repressure the cylinder. If the fluid is leaking past the seat inside the cylinder, you should see a rise in pressure on the pressure gauge.

After checking for leakage, re-install the original plumbing and run the cylinder to the opposite end and repeat the test. Occasionally a cylinder will leak at one point in its stroke due to a scratch or dent in the barrel.

Check suspected position in mid stroke by installing a positive stoop at the suspected position and run the piston rod against it for testing as stated above. Occasionally a piston seal may leak intermittently. This is usually caused by soft packing or O-ring moving slightly or rolling into different positions on the piston and is more likely to happen on cylinders of large bore.

Cylinder pistons with metal ring seals can be expected to have small amount of leakage across rings. Even “Leak-tight” soft seals may have a small bypass during new seal break-in or after seals are well worn.

If you find you have a faulty cylinder, make sure you have it repaired – or a new cylinder fabricated – to maintain optimum performance. A hydraulic repair facility with a full machine shop will be best able to give you the best possible outcome.