Lift Trucks Mast System Testing & Adjusting
Drift Test
Drift is movement of the mast or carriage that is the
result of hydraulic leakage in the cylinders or control
valve. Before testing the drift:
Personal injury can be caused by sudden
movement of the mast or carriage. Use wood blocks
and clamps to hold the mast in this position. Keep
hands and feet clear of any parts that can move.
1. Check the chain adjustment and tilt cylinder
alignment and make necessary adjustments.
2. Lift the mast approximately 762 mm (30 in). Use
wood blocks and clamps to hold the mast in this
position.
3. Check the mast hinge bolts to make sure they are
tight.
4. Remove the blocks and clamps and lower the
mast.
Drift Test For Lift System
1. Secure a rated capacity load on the forks of the lift
truck. Operate the lift truck through a complete lift
and tilt cycle until the oil is at normal temperature
of operation, 45 to 55 ¡C (113 to 131 ¡F).
2. Put the mast in a vertical position.
Raise a rated capacity load to a sufficient height to
test the lift cylinders.
3. Measure any drift of the carriage for a ten minute
period. Drift for all models shall not exceed 100.0
mm (4.00 in).
Tilt Cylinder Adjustment
Tilt cylinder pivot eyes can loosen if the torque on
the pivot eye clamping bolt is not tight enough.
This will let the tilt cylinder rod turn in the tilt
cylinder eye. The cylinder rod may twist out of the
pivot eye and the tilt cylinder will be out of
alignment or may let the mast fall and cause
personal injury or damage. When the rod lengths
are made even, the tilt angle differences or the
mast alignment will no longer be a problem.
To correct the tilt angle or tilt cylinder length, an
adjustment must be made to the tilt cylinder as follows :
Tilt Cylinder Adjustment
(1) Pivot eye. (2) Bolt. (3) Rod.
1. Loosen bolt (2) at pivot eye (1).
2. Turn rod (3) into or out of pivot eye (1) to obtain
the correct length. The minimum length from the end
of rod to the rear face of eye is 32 mm (1.26 in).
3. Tighten bolt (2) and the nut to a torque of 95 L 15
N¥m (70 L 10 lb¥ft).
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