Toro Groundsmaster 4100-D Service Manual page 57

Mow Circuit
A four section gear pump is coupled to the piston (trac-
tion) pump. Hydraulic flow for the mow circuit is supplied
by two sections of the gear pump. The gear pump sec-
tion closest to the piston (traction) pump supplies hy-
draulic flow to the wing cutting decks, while the next gear
pump section supplies the center cutting deck.
Each cutting deck section is controlled by a hydraulic
manifold equipped with a solenoid control valve (S), by-
pass cartridge (LC1), brake cartridge (LC2) and two (2)
relief cartridges (RV1 and RV2). Circuit pressure can be
measured at port (G) of the hydraulic manifold for each
cutting deck.
NOTE: To engage the mow circuit, the operator must
be in the operator seat, the cutting deck(s) must be fully
lowered and the traction speed must be in the Low
speed (4WD) position.
PTO Not Engaged
When the PTO switch is OFF or if the deck or wing deck
is raised with the PTO switch ON, the PTO manifold so-
lenoid valve (S) is not energized and the solenoid spool
is in the neutral position. This solenoid spool in neutral
allows a small amount of hydraulic flow to return to tank
through a manifold sensing line which causes a pres-
sure increase that shifts bypass cartridge LC1. The
pump flow is routed through shifted LC1 and out man-
ifold port P2. Brake cartridge LC2 remains in the un-
shifted position to prevent any return flow from the deck
motor to keep the motor from rotating.
Return flow from the front and right PTO manifolds is
routed through the oil cooler, oil filter and then to the gear
pump input. Return flow from the left PTO manifold pro-
vides supply for the right deck.
PTO Engaged
When the PTO switch is turned ON and the deck is low-
ered, the PTO manifold solenoid valve (S) is energized
by the TEC--5001 controller. This shifted solenoid valve
prevents any sense line flow through the valve which al-
lows the bypass cartridge LC1 to be in its neutral posi-
tion. Gear pump flow entering the manifold is routed out
manifold port M1 and to the cutting deck motor. The re-
turn flow from the deck motor re--enters manifold port
M2. The shifted solenoid valve (S) allows a small
amount of this return flow to return to tank through a
manifold sensing line which causes a pressure increase
that shifts brake cartridge LC2. Hydraulic flow is routed
through shifted LC2, out manifold port P2, through the
oil cooler and filter and then is routed to the gear pump
input. The deck motor continues to rotate as long as so-
lenoid valve (S) is energized.
Groundsmaster 4100--D/4110--D
Deck motor case drain leakage returns to the hydraulic
reservoir.
PTO Circuit Relief
Maximum mow circuit pressure is limited for each deck
by a relief valve (RV1) in the PTO manifold. The center
and left deck relief valves are set at 3000 PSI (207 bar)
and the right deck relief valve is set at 2000 PSI (138
bar).
Relief valve (RV1) and bypass cartridge (LC1) work to-
gether as a two stage relief. When increased circuit re-
sistance is met or if a cutting blade should strike an
object, the pressure increase is felt at the relief valve. If
the pressure should exceed the relief valve setting, the
relief valve will open, creating a small amount of hydrau-
lic flow to return to tank through a manifold sensing line.
This flow causes a pressure increase that shifts bypass
cartridge LC1 and diverts circuit flow away from the deck
motor to manifold port P2 (Fig. 10). When circuit pres-
sure lowers, relief valve (RV1) closes which returns by-
pass cartridge LC1 back to its neutral position allowing
flow to return to the deck motor.
FRONT PTO
MANIFOLD
Page 4 - - 19
SOLENOID S ENERGIZED
DECK MOTOR STALLED
RV1 SHIFTED
LC1 SHIFTED
Figure 10
Hydraulic System