Toro Groundsmaster 3280-D Service Manual page 134

Charge Pressure Test (Using Pressure Gauge) (Machine Serial
Numbers below 316000000) (continued)
Hydraulic System: Testing the Hydraulic System
4. Clean the area around the 1/8 inch pipe plug located on the top of the
transmission between the 2 check valves
the plug from the transmission.
5. Connect a 6,900 kPa (1,000 psi) hydraulic pressure gauge to the transmission
opening.
6. After installing pressure gauge, start engine, and run at idle speed. Check for
any hydraulic leakage from test connections and correct before proceeding
with test.
7. Run engine at full speed (3,150 to 3,250 rpm). Use a tachometer to verify
that engine speed is correct.
8. Observe pressure gauge. The pressure reading should be approximately the
same as counterbalance pressure.
9. Turn off machine. Record test results.
10. Perform a dynamic charge pressure test to identify possible hydrostat (pump
or motor) problems as follows:
A. With pressure gauge still connected, sit in the operator seat, start engine,
and press the traction pedal to forward.
B. While machine is moving straight ahead on level ground (no turning
or deck lifting), monitor the pressure reading on the pressure gauge.
Record test results.
11. The pressure should drop no more than 15% from initial test reading (step 8).
A pressure drop of more than 15% may indicate a traction circuit leak (e.g.,
check valve not seating, worn or damaged hydrostat).
If charge pressure drop is more than 15%, inspect the condition of the
charge pump gerotor and internal housing; refer to Charge Pump Service
in the Sauer-Danfoss (Sundstrand) 15 Series Service Manual at the end of
this chapter.
If the charge pump is in good condition (no scoring, scratches, or excessive
wear), the general condition of the transmission's piston pump and piston
motor might be suspected of wear and inefficiency.
12. Disconnect pressure gauge from the transmission. Install pipe plug back in
the transmission. Check hydraulic-fluid level in reservoir (front axle).
(Figure 59
Page 5–50
and Figure 60). Remove
Groundsmaster ® 3280-D/3320
05138SL Rev B