Toro Groundsmaster 4700-D Service Manual page 73

Lift/Lower Circuit Problems
Problem
Cutting decks will not raise.
NOTE: Operator must be in seat in
order to raise the cutting decks.
Cutting decks raise, but will not stay
up.
NOTE: Lift cylinders cannot provide
an absolutely perfect seal. The lift
arms will eventually lower if left in
the raised position during storage.
Cutting decks will not lower.
NOTE: Operator must be in seat
and traction system must be in low
speed (4WD) in order to lower the
cutting decks.
Groundsmaster 4500--D/4700--D
Possible Cause
Operator seat is unoccupied.
Hydraulic oil level in reservoir is low.
Electrical problem exists that prevents lift control manifold solenoid
valve operation (see Chapter 5 -- Electrical System).
Lift cylinder(s) is (are) damaged.
Lift arm pivots are binding.
Lift/lower circuit relief valve in lift control manifold is stuck open.
Solenoid valve in lift control manifold is damaged or sticking.
Flow divider (FD) in fan control manifold is faulty.
Gear pump section (P3) is worn or damaged (NOTE: A worn or dam-
aged gear pump section (P3) will also affect the traction (charge) and
steering circuits).
Lift circuit hydraulic lines or fittings are leaking.
Cartridge valve in lift control manifold is stuck open.
Air exists in lift circuit.
Lift cylinder is damaged.
Operator seat is unoccupied.
Traction system is in high speed (2WD).
Lift arm pivots are binding.
Lift cylinder is damaged.
Proportional relief cartridge valve (TS) in lift control manifold is dam-
aged or sticking.
Page 4 - - 39 Hydraulic System