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November 2008
Problems
The boom cannot be moved up
The boom jerks when moved down
The boom telescopes are frequently
out of sequence
When the boom is moved up or
down, the forks cannot be levelled
Document 57.0009.0427
Causes
Main valve not well calibrated.
Mechanical jamming.
The line feeding the cylinders is defective
or damaged.
Lifting cylinder damaged.
Block valve damaged.
Main valve not well calibrated.
Block valve damaged.
S e a l s o f t h e e x t e n s i o n c y l i n d e r
damaged.
Re-sequencing valves damaged.
Air in the circuit.
Balancing cylinder damaged.
GTH-4017EX GTH-4514EX GTH-4013EX
Section 5 - Problems-Causes-Solutions
-
PROBLEMS
CAUSES
Solutions
Check if the main valve reaches the max
working pressure (see par. 2 - section
"Technical Specifications").
Check the efficiency of the internal
sliders of the main valve.
Check the boom. In case of mechanical
jamming, rectify.
Check and replace any defective parts
which stop the flow of the hydraulic oil
to the cylinders.
Change the seals and check the
tightness of the cylinder.
Remove and clean the valve; check its
seals and replace if necessary.
Check if the main valve reaches the max
working pressure (see par. 2 - section
"Technical Specifications").
Check the efficiency of the internal
sliders of the Walvoil main valve.
Remove and clean the valve; check its
seals and replace if necessary.
Change the seals and check the
tightness of the cylinder.
Remove and clean the valves; check
their seals and replace if necessary.
Bleed (see Operator's manual).
Check the cylinder efficiency and the
state of the internal seals.
-
SOLUTIONS
13
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