Toro Groundsmaster 3500 30807 Service Manual page 117

Steering/Lift/Sidewinder Circuit Testing − Gear
Pump (P2) Flow Test:
Gear pump (P2) is designed to satisfy both steering cyl-
inder and lift/sidewinder cylinder needs simultaneously
(at full speed throttle). The Gear Pump (P2) Flow Test
compares fluid flow at No Load with fluid flow Under
Load. A drop in flow under load of more than 15% indic-
ates the gears and wear plates in the pump have worn.
Continued operation with a worn pump can generate ex-
cessive heat and cause damage to the seals and other
components in the hydraulic system.
If unit steering is sluggish or otherwise performs poorly,
see Steering/Lift/Sidewinder Circuit − Steering Control
Valve and Steering Cylinder Test in this chapter.
If cutting deck lift or sidewinder operation is unsatisfact-
ory, check lift/sidewinder control valve and/or lift and
sidewinder cylinders. Additional information on these
components is available in this chapter.
If both steering and lift operations perform poorly, per-
form the gear pump (P2) flow test and circuit relief valve
pressure test (see Steering/Lift/Sidewinder Circuit − Re-
lief Valve Pressure Test in this chapter).
Special Equipment Required:
S Flow Meter with Pressure Gauge that has at least
a 5 GPM (16 LPM) capacity.
S Phototach (non−contact tachometer).
1. Park machine on a level surface with the cutting units
lowered and PTO switch off. The engine should be off
and the parking brake engaged.
2. Read Precautions for Hydraulic Testing in this
chapter.
3. Disconnect hose connection on the gear pump (P2)
leading to the steering control valve (Fig. 38).
4. Install tester between gear pump and the discon-
nected hose.
5. Make sure the flow control valve on the tester is fully
open.
6. Start engine and move throttle to full speed (Diesel
engine = 3220 + 50 RPM, Gas engine = 3420 + 30
RPM).
7. Make sure hydraulic fluid is at normal operating tem-
perature by operating the machine for approximately 10
minutes.
Use a phototach to verify that the pump speed is ap-
proximately 2850 RPM.
Groundsmaster 3500
RIGHT
FRONT
1. Gear pump assembly
8. Verify pump flow at No Load as follows:
Record tester pressure and flow readings at no load.
Unrestricted pump output should be approximately
3.8 GPM (14.4 LPM).
9. Verify pump flow Under Load as follows:
Do not close tester valve fully when perform-
ing this test. In this test, the hydraulic tester is
positioned before the manifold relief valve.
Pump damage can occur if the fluid flow is fully
restricted by fully closing the tester flow con-
trol valve.
A. Watch pressure gauge carefully while slowly
closing the flow control valve until 800 PSI (55.2 Bar)
is obtained on gauge.
B. Record tester pressure and flow readings under
load.
10.Set throttle to low speed and shut off engine.
11. The under load test flow reading (step 9.B) should
not drop more than 15% when compared to the no load
test flow reading (step 8.A). A difference in flow of more
than 15%, or the inability to achieve specified pressure
may indicate:
A. A restriction in the pump intake line
B. A Worn and/or slipping drive belt
C. The gear pump (P1) is worn and should be re-
paired or replaced
Page 5 − 59
2
P2
P1
Figure 38
2. To steering control valve
CAUTION
Hydraulic System
1