TL33 Work Platform 4-20
4.14 Adjustment of Overcentre Valves
on lift cylinders.
The valve supplier delivers the overcentre valve pre-set to
specification and SHOULD NOT be adjusted by the user.
In the event of the valve having been tampered with the
advisable course of action is to fit a replacement cartridge.
A short term solution is to temporarily adjust the valve as
follows :-
a) Place 215 kg. evenly distributed in the cage.
b) Raise the boom to about 50mm stroke on the
cylinder.
c) Using a screw driver adjust the spring setting
screw on the valve cartridge.
Turning the screw clockwise increases the
pressure setting. Turning the screw anticlockwise
reduces the setting and allows the boom to creep
downwards. Adjust the spring setting until the
boom just begins to creep downwards.
d) Screw the adjuster 1 (one) further turn
clockwise and secure locknut.
This operation should only be carried out by suitably
qualified and/or experienced personnel.
An incorrectly adjusted valve may cause one of
the following problems:-
Cylinder creeps down under load less than the SWL.
Jerky motion in cylinder & boom when lowering.
Pump under high load when lowering.
Valve does not hold load if hose connections are
loosened or broken.
Damaged seals in cylinders due to high ambient
temperature rise.
CAUTION
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