21 - 2
Flow and Pressure Testing
Auxiliary Pump
On some machines a second pump is mounted on the right
side of the engine and driven by an auxiliary power take off.
The unit supplies additional flow to the excavator valve.
If a hydraulic fault is suspected, check flow and pressure of
the pump before removing and dismantling the unit.
!!
WARNING
Hydraulic fluid at system pressure can injure you. Before
disconnecting or connecting hydraulic hoses, stop the
engine and operate the controls to release pressure
trapped in the hoses. Make sure the engine cannot be
started while the hoses are open.
INT-3-1-11/1
!!
WARNING
Take care when disconnecting hydraulic hoses and
fittings as the oil will be HOT.
TRANS 1-2
1 Switch off the engine and remove the starter key.
2 Relieve residual system pressure by operating the
excavator controls a few times.
3 Disconnect the pump outlet hose from port A. Connect
a flow meter (service tool 892/00268 )and load valve
(service tool 892/00270) in the line between the pump
outlet port and the hose.
Note: Make sure the flow meter is installed with its arrow
pointing away from the pump. Make sure the load valve is in
the open position, i.e. with the adjusting knob screwed fully
out.
4 Connect a 0-400 bar (0-6000 lbf/in
2
) pressure gauge to
the test point X.
5 Start the engine and bring the hydraulics up to working
temperature 50ºC (122ºF). Set the engine speed to
2000 rpm.
6 Carefully adjust the load valve to steadily increase the
pressure so that the pressure gauge reads just below
the MRV setting.
7 Observe the pressure and flow readings achieved,
these should be as given in Technical Data.
8 If the flow is less than that specified replace the pump
complete. DO NOT individually renew the gears or the
housing as this will not effect a permanent cure.
9 When testing is complete repeat steps 1 and 2.
Remove the flow meter and the pressure gauge.
Reconnect the pump outlet hose to port A and refit the
blanking cap to test point X.
Section E Hydraulics
9803/7130
Section E
21 - 2
Issue 1
Service Procedures
A230530
X
AA
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