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Hydraulic troubleshooting and repair problems

Cartridge valve checks before replacement (check, flow control, solenoid, relief)

If its a cartridge valve pull out of the manifold and look at the nose of the cartridge. If there is a screen then see if its clean and try blowing compressed air on, in, and around it. If there is no screen then try pushing on the nose of the cartridge with a small screw driver (be careful not to damage anything). There may be only spring pressure holding it down. Actuate multiple times blowing compressed air into it to try cleaning any debris out. This will work if its a check valve, solenoid cartridge valve, flow control, or dump valve. To do on a relief valve you may have to back the control all the way out and reset the setting afterwards (this may be difficult if you do not understand hydraulic systems).

Coolant in hydraulic oil


Horizontal or Vertical machine center

  1. Make sure center cap on chuck is installed

  2. Chip tray clogged in back of actuator draw tube on opposite end of chuck. Check that the drain hose is not clogged and exit area is clear.

  1. Rotary table seals inside are bad

  2. Draw bar sometimes has hydraulics and coolant going through them, possible seals bad

Low Hydraulic pressure

Type: Variable displacement pump Check compensator pressure setting. Some pumps have both a flow setting and a pressure adjustment valve. If there is only one it should be pressure setting. There will also be a separate manifold with the relief valve that should be set a minimum 200PSI higher. Check relief valve cartridge is not stuck open. Remove the cartridge and look for dirt in the nose of valve.

Type:Variable speed motor that controls pump flow. Pumps may have a transducer that is faulty. Also could be settings were messed with on digital display. Check relief valve cartridge is not stuck open. Remove the cartridge and look for dirt in the nose of valve.

Type:Fixed displacement pump with dump valve Check the relief setting. The relief can be adjusted when dump valve is energized only. Check relief and dump valve cartridge are not stuck open. Remove the cartridges and look for dirt in the nose of valve.

Pneumatic troubleshooting

Pneumatic actuated door or air cylinders

  1. Air Cylinders may have an adjustable air cushion on them. This orifice gets can get clogged from dirty or water in your air supply. Take apart and clean

  2. Check for chips or restriction in door track.

  3. Look for flow controls either mounted on cylinder or valve assembly to adjust speed. Most flow controls meter on the opposite side that the air comes in.

  4. Make sure exhaust mufflers are clean. This can cause air starvation and slow actuation.