Mow Circuit - Toro Groundsmaster 4100-D Service Manual

Mow Circuit

Hydraulic flow for the mow circuit is supplied by two sec-
tions of the gear pump. The gear pump section closest
to the piston (traction) pump supplies hydraulic flow to
the wing decks, while the next gear pump section sup-
plies the center deck.
Each cutting deck is controlled by a hydraulic manifold
equipped with a solenoid control valve (SV1), bypass
cartridge (BY1), brake cartridge (BR1), and relief car-
tridge (R1BR). When the the deck solenoid valve (SV1)
is not energized (PTO switch OFF), hydraulic flow by--
passes the deck motor through the bypass cartridge
(BY1). When the PTO switch is turned ON, the solenoid
valve (SV1) energizes, causing a shift of the by--pass
cartridge (BY1) and allowing hydraulic flow to the deck
motor. Brake cartridge (BR1) and relief cartridge
(R1BR) control the stopping rate of the blade when the
solenoid control valve is de--energized as the PTO
switch is turned OFF.
The solenoid valve (SV1) for each wing deck is de--ener-
gized any time the wing deck is raised.
Return oil from the deck motors is directed to the oil cool-
er and oil filter. Deck motor case drain leakage returns
to the hydraulic reservoir.
Maximum mow circuit pressure is limited at each deck
by a relief valve (R1BY) in the hydraulic manifold. The
center and left wing deck relief valves are set at 3000
PSI and the right wing deck relief valve is set at 2000
PSI.
Circuit pressure can be measured at port (G) of the hy-
draulic manifold for each cutting deck.
Cutting Deck Blade Braking
When the operator turns the cutting deck OFF, solenoid
valve (SV1) is de--energized causing logic cartridge
(BY1) to shift (Fig. 9). This shifted valve allows oil return
to the oil cooler and gear pump. Hydraulic pressure is re-
duced to the cutting deck motor which begins to slow the
cutting blades and also causes logic cartridge (BR1) to
shift (Fig. 10).
The inertia of the rotating cutting blades increases pres-
sure of the oil return to the deck control manifold. This
pressure increase, along with the shifted logic cartridge
(BR1), causes relief valve (R1BR) to shift, which bleeds
the residual pressure in the circuit and allows the blades
to stop in a controlled manner (Fig. 11).
Groundsmaster 4100--D
TO DECK
MOTOR
FROM DECK
MOTOR
TO DECK
MOTOR
FROM DECK
MOTOR
TO DECK
MOTOR
FROM DECK
MOTOR
Rev. E
Page 4 - - 15
PUMP FLOW
RETURN
Figure 9
PUMP FLOW
RETURN
Figure 10
PUMP FLOW
RETURN
Figure 11
Hydraulic System