Groundsmaster 4300--D Hydraulic SystemPage 4 -- 53
4. Raise and support operator seat to allow access to
hydraulic pump.
5. Thoroughly clean both ends of the hydraulic hose
that connects gear pump (P4) outlet (Fig. 54) and lift
control manifold P4 port. Remove hydraulic hose. Ac-
cess tohydraulic hoseat liftcontrol manifoldcan beob-
tained from below the machine.
IMPORTANT: Make sure that the oil flow indicator
arrow on the flow meter is showing that the oil will
flow from pump (P4), through the t ester and to the
lift control manifold.
6. Install testerwith pressuregauges andflow meterin
placeof theremovedhydraulic hose.Connect testerin-
let hose to the pump fitting. Connect the tester outlet
hose to the lift c ontrol manifold fitting. Make sure the
flow control valve on tester is fully open.
7. Makesurethatthetractionpedalisinneutralandthe
parking brake is engaged.
8. Startengineandrunatidlespeed.Checkforanyhy-
draulic leakage from test connections and correct be-
fore proceeding with test.
9. Move throttle to full speed (3200 RPM).Usea
tachometer to verify that engine speed is correct.
IMPORTANT: The gear pump is a positive displace-
ment type. If pump flow is completely restricted or
stopped, damage to the pump, tester or other com-
ponents could occur.
10.While carefully watching pressure gauges, slowly
closethetesterflowcontrolvalveuntil1000PSI(70bar)
is obtained on gauge.
FLOW TESTER READING TO BE: A pump in good
condition should have a flow of approximately 3.2
GPM (11.9 LPM) at 1000 PSI (70 bar).
11.Open the tester flow control valve, stop engine and
record test results.
12.Ifflowislessthan2.8 GPM (10.6 LPM) orapressure
of 1000 PSI (70 bar) cannot be obtained, consider that
apumpproblemexists.Checkforrestrictioninpumpin-
take line. If intake is not restricted, remove gear pump
and repair or replace pump as necessary (see Gear
Pump in the Service and Repairs section of this chap-
ter).
NOTE: Iftheflowfromgearpump(P4)islow,theopera-
tion of all lift cylinders will be affected.
13.After testing is completed, make sure that engine is
stopped, then relieve hydraulic system pressure (see
RelievingHydraulic SystemPressure intheGeneralIn-
formation section of this chapter). Remove tester and
connectremovedhydraulichosetogearpump(P4)out-
let and lift control manifold P port.
14.Lower and secure operator seat.
1. Gear pump (P4) 2. Hydraulic hose
Figure 54
2
1
Hydraulic
System
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