Service Manual

Groundsmaster 4500--D/4700--DHydraulic System Page 4 -- 36
Traction Circuit Problems
NOTE: Whentroubleshootingtractioncircuitproblems,
if a problem exists in both low (4WD) and high (2WD)
speeds,consider a faulty component thataffectstheen-
tire traction circuit (e.g. charge circuit, relief valves, pis-
ton pump, front wheel motors). If the problem exists in
low speed (4WD) but not in high speed (2WD), consider
aproblem in the4WDtractionsystem(e.g.rear axle mo-
tor, cartridge valves in 4WD/2WD control manifold).
Problem Possible Cause
Machine operates in one direction
only.
Traction control linkage is faulty.
Traction relief valve is defective.
Traction pedal reaction is sluggish
when in either low speed (4WD) or
high speed (2WD).
Traction control linkage is stuck or binding.
Charge pressure is low.
Piston (traction) pump servo control valve orifices are plugged or
damaged.
Traction pedal reaction is sluggish
when in low speed (4WD). Pedal
reaction is normal when in high
speed (2WD).
PD1 and PD2 pilot directional valve seals in 4WD/2WD control
manifold are leaking or damaged.
Machine travels too far before stop-
ping when the traction pedal is re-
leased.
Traction linkage is out of adjustment.
Charge pressure is low.
Piston (traction) pump servo control valve orifices are plugged or
damaged.
Traction pedal does not return to neutral.
Traction power is lost or machine will
not operate in either direction.
Hydraulic reservoir oil level is low.
Piston pump bypass valve is open or damaged.
Charge pressure is low.
Traction circuit pressure is low.
Front wheel motor couplers are damaged.
If traction is lost in low speed (4WD) but is normal in high speed
(2WD), rear axle motor or rear axle motor drive may be faulty.
Low speed (4WD) will not engage. Electrical problem exists (see Chapter 5 -- Electrical System).
Solenoid valve SV in 4WD/2WD control manifold is faulty.
Cartridge valve(s) in 4WD/2WD control manifold is (are) faulty.
Low speed (4WD) will not disen-
gage.
Electrical problem exists (see Chapter 5 -- Electrical System).
Cutting decks are fully lowered.
Cartridge valve in 4WD/2WD control manifold is damaged or sticking.