Toro Groundsmaster 7200 Service Manual page 75

The Gear Pump Flow Test should be performed if a cut-
ting deck (or implement) raise and lower problem is
identified. This test will determine if hydraulic flow from
the gear pump is correct.
Procedure for Gear Pump Flow Test:
NOTE: Over a period of time, the gears and wear plates
in the gear pump can wear. A worn pump will by–pass
oil and make the pump less efficient. Eventually, enough
oil loss will occur to cause the cutting unit motors to stall
under heavy cutting conditions. Continued operation
with a worn, inefficient pump can generate excessive
heat and cause damage to seals and other components
in the hydraulic system.
1. Make sure hydraulic oil is at normal operating tem-
perature.
2. Make sure that traction drive is correctly adjusted for
the neutral position.
WARNING
Before disconnecting or performing any work on
the hydraulic system, all pressure in the system
must be relieved. See Relieving Hydraulic System
Pressure in the General Information section.
3. Park machine on a level surface with the cutting deck
lowered and off. Make sure engine is off and the parking
brake is engaged.
4. Read Precautions for Hydraulic Testing listed at the
beginning of this section.
5. Thoroughly clean junction of hydraulic hose and low-
er fitting on rear of lift control valve.
6. Disconnect hydraulic hose from lower fitting on rear
of lift control valve (Fig. 25). This hose is from the gear
pump outlet and provides oil flow to the lift control valve.
7. Install hydraulic tester (pressure and flow) in series
with the gear pump fitting and the disconnected hose.
Make sure that tester flow arrow points from the pump
outlet port and toward the disconnected hose. Make
sure the flow control valve on the tester is fully
open.
8. Start engine and run at low idle speed (1500 to 1650
RPM). Check for any hydraulic leakage from test con-
nections and correct before proceeding with test.
Groundsmaster 7200/7210
9. With engine running, move throttle to full speed
(3200 RPM).
10.Watch tester pressure gauge carefully while slowly
closing the flow control valve until 1000 PSI (69 bar) is
obtained. Do not close tester load valve fully. Verify with
a phototac that the engine speed remains 3200 RPM
while maintaining 1000 PSI (69 bar) on the tester pres-
sure gauge.
11. Observe flow gauge. Flow indication for a pump in
good condition is 5.4 GPM (20.4 LPM).
12.Open tester load valve and then stop engine. Record
test results.
13.Normal pump flow is 5.4 GPM (20.4 LPM). Lower
pump flow would result in reduced circuit performance.
If flow was less than 4.8 GPM (18.2 LPM) or a pressure
of 1000 PSI (69 bar) cannot be obtained, check for re-
striction in the pump inlet line. If inlet line is not restricted,
remove gear pump and repair or replace as necessary.
NOTE: Implement relief valve pressure can also be
tested with hydraulic tester (pressure and flow) in series
with the gear pump fitting and the disconnected hose.
Use pressure gauges on hydraulic tester and follow pro-
cedure for Implement Relief Pressure Test in this sec-
tion.
14.Relieve hydraulic system pressure (see Relieving
Hydraulic System Pressure in the General Information
section). Disconnect tester from lift control valve fitting
and hydraulic hose. Reconnect hose to the control valve
fitting.
1. Lift control valve
Page 4 – 39
1
2
Figure 25
2. Hose from gear pump
Hydraulic System