Service Manual

Groundsmaster 4500 --D/4700--DHydraulic System Page 4 -- 38
Traction Circuit Problems
NOTE: When troubleshooting traction circuit problems,
if a problem exists in both low (mow) and high (transport)
speeds, consider a faulty component that affects the en-
tire traction circuit (e.g. charge circuit, traction circuit re-
lief valves, piston pump). If the problem exists in LOW
speed (mow) but not in HI speed (transport), consider a
problem that only exists in mow (e.g. swashplate com-
ponents in front wheel or rear axle motor, solenoid valve
in HI/LOW range control manifold).
Problem Possible Cause
Machineoperatesinonedirection
only.
Piston (traction) pump by --pass valve is open or damaged.
Tr action relief valve in piston pump is leaking o r faulty.
Piston (traction) pump servo control valve orifices or screens are
plugged or damaged.
Problem with TEC output to piston (traction) pump servo control
exists (see Chapter 5 -- Electrical System).
Traction pedal reaction is sluggish. Traction pedal components are stuck or binding.
Traction charge pressure is low.
Piston (traction) pump servo control valve orifices are plugged or
damaged.
Machinetravelstoofarbeforestop-
ping when the traction pedal is re-
leased.
Traction pedal components are stuck or binding.
Traction charge pressure is low.
Piston (traction) pump servo control valve orifices are plugged or
damaged.
Traction power is lost or machine will
not operate in either direction.
Hydraulic reservoir oil level is low (NOTE: Other hydraulic systems
are affected as well).
Piston (traction) pump by --pass valve is open or damaged.
Traction charge pressure is low.
Traction circuit pressure is low.
Problem with TEC output to servo control (see Chapter 5 -- Electric-
al System).
LOW traction speed (mow) will not
engage.
NOTE: LOW (mow) will not engage
when the cutting decks are lowered.
Electrical problem exists that prevents solenoid valve in HI/LOW
range control manifold from being de--energized (see Chapter 5 --
Electrical System).
Solenoid valve in HI/LOW range control manifold is faulty.
LOW traction speed (mow) will not
disengage.
Electrical problem exists that prevents solenoid valve in HI/LOW
range control manifold from being energized (see Chapter 5 -- Elec-
trical System).
Solenoid valve in HI/LOW range control manifold is faulty.