March 4, 2016

How to Properly Bleed Air from a Dump Truck Cylinder

Follow the appropriate steps below to properly bleed air from a dump truck cylinder.

Single-Acting or Lift Cylinder:

  1. Raise the dump body and cylinder to full extension and leave extended for several minutes to allow air to raise to the top of the cylinder.
  2. Lower the dump body and cylinder until the front of the dump body is approximately 2 feet off of the chassis frame.
  3. Put the body up lever in the hold position (center).
  4. If you have an outside bleeder valve, crack the valve open at this time.
  5. Wait until all trapped air has escaped from the valve and a full stream of hydraulic oil is escaping from the valve.
  6. At this point the cylinder is bled, and the bleeder valve can be closed.

If your bleeder valve is located on top of the cylinder, you will need to remove the dog house box cover and must also move to the inside of the dump body:

  1. Remove the dog box cover and crack the bleeder valve open at this time.
  2. Wait until all trapped air has escaped from the valve and a full stream of hydraulic oil is escaping from the valve.
  3. At this point the cylinder is bled, and the bleeder valve can be closed.

Rod Type Hydraulic Cylinders:

Before releasing air from the hydraulic cylinder, make sure the hydraulic cylinder is not pressurized in any circumstances. The air valve should be pointing upwards when the hydraulic cylinder is positioned horizontal. The piston rod must be in fully retracted position at first.

  1. Open the air valve at the upper side or the hydraulic cylinder.
  2. Make sure all hoses or pipes are connected properly.
  3. Set-up the hydraulic system and start it up.
  4. Extend the piston rod slowly with no pressure built-up. Keep extending until there is oil/foam coming out of the air valve. (Hydraulic cylinders that go over-center, must be air-released before mounting in the construction!)
  5. Shut down the system and close the air valve.
  6. Depressurize the system before opening the air valve at the lower side of the hydraulic cylinder.
  7. Start up the hydraulic system.
  8. Retract the hydraulic cylinder slowly with no pressure built-up. Keep retracting until there is oil/foam coming out of the air valve.
  9. Shut down the system and close the air valve.
  10. Retest the hydraulic cylinder by extending and retracting the piston rod until it is running smoothly.

At Hydraulic Cylinders Inc, we have the product & knowledge to serve you. Contact us to discuss your hydraulic cylinder needs. Call us at 888-771-1894.