Komatsu F30791, Shop Manual

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CONTROL OF HYDRAULIC DRIFTS - ANALYSIS OF THE CAUSES
OF A DRIFT
20-54
TESTING AND ADJUSTMENTS
CONTROL OF HYDRAULIC DRIFTS -
ANALYSIS OF THE CAUSES OF A DRIFT
H Test conditions:
.
Machine: in the conditions indicated in the NOR-
MAL TECHNICAL DATA.
.
Engine: at working temperature.
. Hydraulic oil: 45 ± 55 ëC.
1. Test
To check on the extent of the hydraulic drifts of
individual components and the total hydraulic
drift, position the machine and follow the proce-
dures indicated in the «NORMAL TECHNICAL
DATA».
2. Analysis of the causes of hydraulic drifts
Before disconnecting the tubes, release hydrau-
lic pressures in the circuits (see «ELIMINATION
OF THE RESIDUAL PRESSURES»).
1. Boom test
1 - Position the machine with the arm vertical and
with the back of the bucket resting on the ground.
2 - Stop the engine and release the residual hydrau-
lic pressures.
3 - Disconnect the hoses (1) and (2) that supply the
cylinder on the head side and on the base side.
4 - Plug the two hoses to prevent entry of impurities.
5 - Plug the rigid tube (3) that supplies the cylinder
on the base side.
6 - In order to catch any oil leakages, attach a tube
to the pipe (4) that supplies the head side of
the cylinder.
7 - Start the engine and extend the arm completely.
8 - Stop the engine and check the position of the
boom for 15 minutes.
.
If the boom moves downwards the drift is due
to the cylinder gaskets.
. If the boom does not move, the drift is due to
the control valve.
PC20R-8 PC27R-8
RKPA2470
2
3
1
4
RKP04990