Fixed Flow Pumps
Flow and Pressure Testing
Before removing the pump it is necessary to determine the
source of any problem by measuring the output flow at
system pressure from both of the pump outlet ports.
To check flow it is necessary to fit flow meter A into the
output line of each pump section in turn. If available, load
valve B (service tool 892/00270) should also be installed (see
Note 1). Make sure the flow meter is installed with its arrow
pointing away from the pump and, if applicable, located
between the pump and the load valve.
Note 1: If no load valve is available, ignore the references to
the load valve in Fitting/Removing a Flow Meter and Load
Valve below. An alternative method of determining flow is
included in the Checking Flow procedures following.
Fitting/Removing a Flow Meter and Load
Valve
Before fitting/removing a flow meter and load valve, switch
off the machine and operate the loader/excavator controls a
few times to vent system pressure.
!
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
Fitting
1aPump section 1 - disconnect hose C from the
pump. Fit the flow meter and load valve (see Note
2) between hose C and the pump.
b Pump section 2 - disconnect hose D from the
pump. Fit the flow meter and load valve (see Note
2) between hose D and the pump.
Note 2: Make sure the load valve is in the open position, i.e.
with the adjusting knob screwed fully out, before carrying
out the Checking Flow procedure.
Removing
Removing is the reverse of fitting.
Checking Flow
1 Check the setting of the Main Relief Valve (MRV) as
described in Loader Valve, Pressure Testing. Adjust if
necessary.
2aUsing a load valve - fit a flow meter and load valve,
as described in Fitting, to each pump outlet in turn.
Fit a 0-400 bar (0-6000 lbf/in
2
) pressure gauge to
the load valve pressure test connector.
b If no load valve is available - fit a flow meter, as
described in Fitting, to each pump output in turn.
3 Start the engine and bring the hydraulics up to working
temperature 50ºC (122ºF). Set the engine speed to
2200 rpm.
4aUsing a load valve - adjust the load valve so that
the pressure gauge reading is just below the MRV
setting.
b If no load valve is available - raise or lower the
loader arms until the rams are fully open or closed.
Continue to operate the raise/lower control so that
system pressure builds up. Watch the flow meter
and note its reading at the moment the MRV
operates.
5 The flow reading should be as listed in Technical
Data.
21 - 2
Section E
Hydraulics
9803/3280
Section E
21 - 2
Issue 1
Service Procedures
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