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Groundsmaster 4000--D Hydraulic System (Rev. B)Page 4 -- 41
Procedure for Steering and Lift/Lower Gear Pump
Flow Test
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.
1. Make sure hydraulic oil is at normal operating tem-
perature by operating the machine for approximately 10
minutes. Make sure the hydraulic tank is full.
2. Park machine on alevel surface withthe cutting units
lowered and off. Make sure engine is off and the parking
brake is engaged.
CAUTION
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.
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
tester in series between the last gear pump s ection and
one of the circuit hoses (Fig. 30). 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. Start the engine and movethrottle to full speed (2730
+
30 RPM). DO NOT engage the cutting units.
5. While watching pressure gauges, slowly close flow
control valve until 1000 PSI is obtained on gauge. Verify
engine speed continues to be correct (2730 +
30 RPM).
GAUGE READING TO BE: Flow approximately 3.5
GPM at 1000 PSI.
6. Stop engine. Remove tester and reinstall hose.
Complete steps 3 through 6 for other circuit hose.
7. If the total of the two flows is lower than 7GPMor 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.
If the total of the two flows is 7GPMbut individual circuit
flow is less than 3.5 GPM (e.g.. steering circuit has 2
GPM and lift circuit has 5 GPM), suspect a problem with
the proportional valve in the gear pump.
1. Hydraulic tank cap
2. Lift circuit hose
3. Steering circuit hose
Figure 30
2
3
1
1. Gear pump backplate
2. Lift circuit
3. Steering circuit
4. Proportional valve
Figure 31
1
4
2
3
Hydraulic
System