Toro Groundsmaster 5900 Series Service Manual page 141

Procedure for Traction Circuit Charge Pressure Test (continued)
Groundsmaster ® 5900 & 5910
16227SL Rev B
9. If there is no pressure, or pressure is low, check the following items:
A. Restriction in gear pump intake line or reservoir strainer.
B. Inspect charge pressure relief valve located in the piston pump and
adjust if necessary (see
Pumps Service
an elevated charge pressure can reduce swash−plate response time.
C. Consider that a forward or reverse relief valve in the piston pump is
leaking or damaged.
D. Leakage in the steering/deck lift manifold will affect charge circuit
pressure. Consider that damaged cartridge seals in this manifold will
cause low charge circuit pressure in addition to affecting normal operation
of steering and/or deck lift/lower circuits.
E. If necessary, check for internal damage or worn parts in the final gear
pump section which supplies the charge circuit with hydraulic flow. A
worn or damaged final gear pump section will also affect cutting deck
lift/lower and steering operation.
10. Next, with the pressure gauge still connected to the charge pressure test port,
take a gauge reading while operating the machine in forward and reverse.
Start the engine, release parking brake and run engine at high idle speed
(2530 RPM). Push the traction pedal forward while monitoring the pressure
gauge. Repeat for reverse direction. Stop engine and record test results.
11. If charge pressure meets specifications under no load conditions (step 6
above), but consistently drops more than 15% when under traction load
(step 9 above), the piston (traction) pump and/or wheel motor(s) should be
suspected of wear and inefficiency. When the pump and/or wheel motor(s)
are worn or damaged, the charge circuit is not able to keep up with internal
leakage in traction circuit components.
12. When charge pressure testing is complete, disconnect pressure gauge from
manifold test fitting. Lower and secure hood.
Sauer− Danfoss H1 Closed Circuit Axial Piston
Manual). Keep in mind that operating the machine with
Page 5–41 Hydraulic System: Testing