Service

Normal Service Items

Packing, wipers and bushings are considered normal service or replacement 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 replacements are required.
Cylinders may be subject to leaking oil past the seal for various reasons requiring adjustment of the head/packing nuts. This is considered a normal installation and field service adjustment to correct the leakage.

Warning

Before making adjustments or repairs to the cylinder when mounted in the unit, use strong, heavy, positive supports to hold the body from accidentally lowering which can cause severe injury or death and/or damage to the unit and cylinder. Place control valve in the lower position to insure the pressure is relieved in the cylinder. High pressure can cause severe injury or death and/or damage to the unit and cylinder.

Procedure for adjusting head nuts on Telescopic Cylinders

A. For leaking cylinders:

  1. Loosen set screw(s) in headnut of leaking stage(s).
  2. Tap headnut lightly around circumference with a hammer.
  3. Using a chain wrench, back headnut off one half to one full turn. If plunger turns as you are turning the headnut, the plunger will have to be held, preferably with a strap wrench.
  4. Cycle cylinder two or three times to reset vee ring packing.
  5. Tighten headnut one half turn farther than it was loosened.
  6. Tighten set screw(s).

B. For mis-sequencing cylinders:

  1. Loosen set screw in headnut on stage that is sticking.
  2. Tap headnut lightly around circumference with a hammer.
  3. Using a chain wrench, back off headnut one half turn.
  4. Cycle cylinder.  If cylinder still mis-stages, turn headnut another half turn.
  5. Cycle cylinder. If cylinder still mis-stages, tighten the headnut on the next stage that is extending.  If plunger turns as you are turning the headnut, the plunger will have to be held, preferably with a strap wrench.
  6. Tighten set screw(s). 

C. (a) Instructions for Self-Bleed Type Hydraulic Cylinders

After installation, cycle the cylinder approximately 5 times to remove air. If erratic operation occurs, 
continue to cycle until cycle is smooth. Cylinder will continue to bleed itself during use.

Special considerations:
While the typical 5 cycles is usually sufficient; it may take several more cycles to bleed out enough air 
to eliminate erratic operation. Not all systems are the same and considerably more cycles may be needed 
upon installation.

If air pressure is being used to aid in cylinder installation such as to raise mounting to attachment position, 
it is best to remove air pressure before cycling cylinder.

Older systems may be susceptible to air being induced; make certain that there is no part of the system 
that can allow air to be drawn into the system.

Avoid hose routing that will cause air to be trapped. Large loops in the hose routing will be 
areas for air to collect. Also, it may be more difficult to bleed if the reservoir is far from the cylinder and 
positioned very low with respect to the cylinder.

Always allow adequate air space in hydraulic reservoir per system recommendations.

Upon initial installation it may be necessary to allow time for the air to dissipate from the oil in the reservoir.
Check oil level periodically to avoid reservoir being drained during cylinder cycle.

C. (b) Bleeding air from Single-Acting Telescopic Cylinders

  1. Empty the dump body of any material.
  2. Remove the cover plate from the doghouse of the dump body to access the cylinder bleeder valve.
  3. Fully extend the cylinder, raising the empty dump bed.
  4. Lower the dump bed to within one foot from the frame.
  5. 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.

NOTE: For consistent operation of telescopic cylinders, it is advisable to bleed the 
air from the cylinder weekly. 

If these procedures fail to correct the problem, contact the factory or an authorized 
service center for further instructions.