Toro Groundsmaster 220-D Service Manual page 115

Implement Relief Pressure Test
Using a low pressure gauge,
0 – 1000 psi (0 – 6895 kPa)
1. Perform steps 1 through 7 of the Charge Pressure
Test.
2. With the engine running at 3200 RPM, move the lift
control lever to the RAISE position and allow the cutting
unit or implement to fully raise. Continue to hold the lever
in the RAISE position and observe the pressure gauge.
The pressure reading should be from 700 to 800 PSI
(4826 to 5516 kPa) as the implement relief valve lifts.
3. Move the lift control lever to the LOWER position to
lower the cutting deck (or implement) to the ground.
Shut off engine. Record test results.
4. If the implement relief pressure is below 700 PSI
(4826 kPa), adjust the implement relief valve in the
transmission by adding the required amount of shims
from the shim pack (see Implement Relief Valve Service
in the Repairs section of this chapter).
NOTE: For every 0.010 in. (0.254 mm) of shim thick-
ness, there is an approximate 50 PSI (340 kPa) change
in implement relief pressure.
CAUTION
The Implement Relief pressure must not exceed
800 psi (5516 kPaa).
If adding shims to the relief valve does not increase
pressure, inspect the condition of the charge pump ger-
otor and internal housing (see Charge Pump Service in
the Repairs section 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. A lack of mini-
mum implement relief pressure could be due to the
charge pump having to direct all flow to the main traction
circuit (piston pump and piston motor).
Testing
NOTE: If the implement relief pressure is 700 to 800
PSI (4826 to 5516 kPa) and a steering or lift problem oc-
curs, inspect for a problem unrelated to the hydraulic cir-
cuit (e.g. binding steering or lift system components,
debris build–up on/under the cutting deck). Check and
repair other items before continuing with hydraulic tests.
5. Disconnect pressure gauge from the transmission.
Install pipe plug back in the transmission. Check hy-
draulic oil level in reservoir (front axle).
At this point, a traction pressure test could be used to de-
termine whether the hydrostatic transmission has ex-
cessive piston group leakage and needs to be repaired
(see Testing Traction Pressure).
Rev. H
Page 4 – 17
Groundsmaster 220–D