Procedure for Steering and Lift/Lower Gear Pump
Flow Test
7. If the total of the two flows is lower than 6.4 GPM or
a pressure of 1000 PSI could not be obtained, check for
restriction in pump intake line. If intake line is not re-
stricted, remove gear pump and repair or replace as
necessary.
Output from the steering and lift/lower gear pump sec-
tion is equally divided by a proportional valve to provide
flow to the steering circuit and the lift circuit. To test gear
pump flow, testing of both circuits is required. Total gear
pump flow is the combined flow from the two circuits.
If the total of the two flows is 6.4 GPM but individual cir-
cuit flow is less than 3.2 GPM (e.g. steering circuit has
2
with the proportional valve in the gear pump.
GPM and lift circuit has 4.4 GPM), suspect a problem
1.
perature by operating the machine for approximately 10
minutes. Make sure the hydraulic tank is full.
Make sure hydraulic oil is at normal operating tem-
2.
lowered and off. Make sure engine is off and the parking
brake is engaged.
Parkmachineonalevelsurfacewiththecuttingunits
2
CAUTION
3
1
Prevent personal injury and/or damage to equip-
ment. Read all WARNINGS, CAUTIONS, and Pre-
cautions for Hydraulic Testing at the beginning
of this section.
Figure 42
1.
2.
Gear pump
Lift circuit hose
3.
Steering circuit hose
IMPORTANT: Make sure that the oil flow indicator
arrow on the flow gauge is showing that the oil will
flow from the pump, through the tester, and into the
hydraulic hose.
3.
With the engine off and cutting units lowered, install
1
2
3
tester in series between the last gear pump section and
one of the circuit hoses (Fig. 42). Make sure the tester
flow control valve is OPEN.
IMPORTANT: The pump is a positive displacement
type. If pump flow is completely restricted or
stopped, damage to the pump, tester, or other com-
ponents could occur.
4
4.
+
Starttheengineandmovethrottletofullspeed(2800
50 RPM). DO NOT engage the cutting units.
Figure 43
5.
control valve until 1000 PSI is obtained on gauge. Verify
engine speed continues to be correct (2800 + 50 RPM).
While watching pressure gauges, slowly close flow
1.
2.
Gear pump backplate
Lift circuit
3.
4.
Steering circuit
Proportional valve
FLOW GAUGE READING TO BE: Flow approxi-
mately 3.2 GPM at 1000 PSI.
6.
hosetogearpump.Completesteps3through6forother
circuit hose.
Stop engine. Remove tester and reinstall hydraulic
Groundsmaster 4500--D/4700--D
Page 4 -- 43
Hydraulic System (Rev. A)
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| Language | English |
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