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Telescopic Cylinder Maintenance

Cylinders, Hydraulic Info

WARNING: Before working on a telescopic cylinder mounted on a truck or trailer unit, use supports or holding devices that will absolutely prevent the body from accidentally lowering. Place control valve in the “LOWER” position to assure that all pressure has been relieved from the cylinder.

Telescopic Cylinder Maintenance List

  1. Packing, wipers and bushings are considered normal maintenance or service items. These items are subject to contamination from external and internal foreign materials, many of which are abrasive in nature, causing abnormal wear or damage to the parts, to the extent that replacements are required.
  2. Cylinders may be subject to leaking oil past the seals for various reasons requiring adjustment of head/packing nuts. This adjustment is considered normal maintenance.
  3. Procedure for Adjusting telescopic Cylinder Head Nuts.
    1. Loosen set screw (or set screws) in head nut that holds in packing of leaking stage.
    2. Lightly tap head nut around circumference with a hammer.
    3. Back head nut off 1/2 to 1 full turn using a spanner or chain wrench.
    4. (Note: If stage rotates when head nut is turned, hold stage with strap wrench.)
    5. Cycle cylinder 2 to 3 times to reset chevron vee packing.
    6. Retighten head nut approximately 1/2 turn further than it was when it loosened.
    7. Tighten set screws.
  4. Procedure for Mis-Staging of Mis-Sequencing Cylinder.
    1. Loosen set screws in head nut that holds in packing that fits over stage that is sticking.
    2. Lightly tap head nut around circumference with a hammer.
    3. Back head nut off 1/2 turn using a spanner or chain wrench.
    4. Cycle cylinder, if cylinder still mis-stages back head nut off another 1/2 turn.
    5. Cycle cylinder, if cylinder still mis-stages tighten the head nut of the next stage that is extending.
    6. Tighten set screws.
  5. Bleeding Air from Single-Acting Telescopic Cylinders. For smooth operation on these cylinders, it is advisable to bleed the air from the cylinder weekly. Manual bleeding is accomplished by:
    1. Empty the dump body of any material.
    2. Remove the cover plate from the dog house of the dump body to access the bleeder valve.
    3. Fully extend the cylinder, raising the EMPTY dump bed.
    4. Lower the dump to within 1 foot from resting on the frame.
    5. With the fingers turn the bleeder valve in a counterclockwise direction. This opens the valve and allows the air to escape from the cylinder.
    6. When a steady stream of oil comes from the bleeder, turn the valve in a clockwise direction until it is closed.

If these procedures fail to correct the problem, please contact our Component Sales Team for Instructions at 800.728.5168.