Warren Elevating 5
th
Wheel
35
Mechanical Maintenance
Weekly: Test the locking assembly for correct king pin locking. Make sure that the fifth wheel
locks every time.
Monthly: Check all mounting brackets and bolts to be sure that they are tight. Be sure that the in-
cab controls and PTO light are working correctly.
Service Conditions and Problems
If new unit will not lift empty or loaded trailers:
•
Check oil level in the tank.
•
Check to be sure that the pump is fully shifting into the “raised” position.
•
Check hydraulic lines to ensure no pinch points.
If new unit will raise light loads but not heavy loads:
Listen near the pump. If you hear a chattering noise when the unit stops lifting, the
pressure relief valve may be opening too early. The relief valve may need adjustment or
replacement. The recommended maximum pressure is 2000 psi. Please call us for
adjustment instructions.
If unit has been working properly, and now it will not lift:
After checking all of the above items, the following might be the problem:
Damaged cylinder
Worn pump, causing cavitation of oil
Blockage in hydraulic system
Relief valve is opening, due to very heavy load or relief valve damage
If unit will not stay in a raised position:
Cylinder may be damaged. Piston may be cracked or barrel might be severely scored.
Spool valve in pump might be damaged or may not be shifting fully.
Check valve may be stuck open due to debris.
If elevators are cracking:
Tractor is being operated over rough terrain, especially at high speeds.
Tractor is being driven on public roads for long distances in a raised position.
Trailer load is exceeding rated load for 5
th
wheel.
Bearings and shafts are not being lubricated on regular intervals.
Jaws will not lock:
Jaws, fork or wear plate are damaged.
Air chamber is damaged or an incorrect type of air chamber has been installed on an
older fifth wheel. Driver is not backing under the trailer with enough force.
Oil blowing out of cylinder vent when lowering:
Check oil level in tank. Be sure that the level is about 2” below the top of the cylinder.
On air shift pumps, there should be a restrictor valve on the pressure port of the pump.
Check to be sure that this valve is present. This valve makes the fifth wheel come down
slowly. If you have supplied your own pump, make sure that a flow restrictor is installed.
Check for any hydraulic leaks that might be drawing in air.
