Engine Cooling Fan Circuit
A four section gear pump is coupled to the piston (trac-
tion)pump.Thegearpumpsection farthestfromthepis-
ton pump supplies hydraulic flow for the engine cooling
fan circuit (Fig. 15).
ing oil flow to return to the fan motor but in the reverse
direction causing the motor and cooling fan to run in re-
verse. The controller determines the length of time that
the fan should be run in reverse before fan rotation is re-
turned to the forward direction.
The fan drive manifold controls the operation of the hy-
draulic motor that drives the engine cooling fan in addi-
tion to including the flow divider for the steering and
lift/lower circuits. The fan drive manifold controls the
speed and direction of the fan motor based on electrical
output from the TEC--5002 controller.
2
Oil flow from the gear pump to the cooling fan motor is
controlled by the proportional relief valve (PRV) in the
fan drive manifold. This valve adjusts fan circuit pres-
sure and flow based on a PWM (Pulse Width Modula-
tion)signalfromtheTEC--5002controller.Thecontroller
uses engine coolant and hydraulic oil temperatures as
inputstodeterminetheproperPWMsignalforthe(PRV)
valve. The fan circuit flow determines the speed of the
cooling fan motor and thus, the speed of the cooling fan.
1
If the fan motor is stalled for any reason, the manifold
proportional reliefvalve(PRV)hasasecondary function
as a circuit relief to limit fan motor pressure to 3000 PSI
Figure 15
(207
bar).
1.
Gear pump
2. Fan drive manifold
When the engine is shut off, the over--running inertia
load of the fan blades keeps driving the fan motor and
turnsitintoapump.Thecheckvalve(CV)inthefandrive
manifold will open to keep the motor circuit full of oil so
the fan motor will not cavitate.
REVERSE DIRECTION SHOWN
TO RESERVOIR
TO STEERING
CIRCUIT
TO LIFT/LOWER
CIRCUIT
Forward Direction Fan Operation
M1
M2
L
Oilflowfromthegearpumpissentthrough thede--ener-
gizedfanmanifoldsolenoidvalve(S1)torotatethecool-
ing fan motor. Return flow from the motor re--enters the
manifold (port M2), through the de--energized solenoid
valve(S1), outofthemanifold (portT) andthen isrouted
through the oil cooler and oil filter.
(ENERGIZED)
Reverse Direction Fan Operation (Fig. 16)
The TEC--5002 controller can reverse the cooling fan to
clean debris from the rear intake screen. If hydraulic oil
and/or engine coolant temperatures increase to an un-
suitable level, a high PWM signal is sent to the (PRV)
valve to slow the cooling fan and direct pump oil flow to
the reservoir. The controller then energizes solenoid
valve(S1)inthefandrivemanifoldtoreversecoolingfan
motor oil flow so that the motor runs in the reverse direc-
tion. A lower PWM signal is sent to the PRV valve allow-
P1
T
P2
FAN DRIVE
MANIFOLD
FROM GEAR PUMP
TO OIL COOLER
Figure 16
Groundsmaster 4000--D/4010--D
Page 4 -- 25
Hydraulic System
| Categories | Lawn Mower Manual, Sprinkler and Irrigation Manuals, Toro Sprinkler and Irrigation Manuals |
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