Service Manual

Reelmaster 7000 Hydraulic SystemPage 4 -- 25
Engine Cooling Fan Circuit
A four section gear pump is coupled to the piston (trac-
tion) pump.Thegear pumpsection P4 (farthest fromthe
piston pump) supplies hydraulic flow for the hydraulic
engine cooling fan motor (Fig. 17).
Thefancontrolmanifoldcontrols theoperationofthehy-
draulic motor that drives the engine cooling fan in addi-
tionto including theflow divider (FD)for the steeringand
lift circuits. The electronically controlled proportional re-
liefvalve (PRV)inthe manifoldcontrols the oilflow to the
fan motor. The fan c ontrol manifold controls the speed
and direction of the fan motor based on electrical output
from the TEC controller.
Oil flow from the gear pump to the cooling fan motor is
controlled by the proportional relief valve (PRV) in the
fan control manifold. This valve adjusts fan circuit flow
based on a PWM (Pulse Width Modulation) signal from
the TEC controller. The controller uses engine coolant
and hydraulic oil temperatures as inputs to determine
theproper PWM signal for thePRVvalve. The fanc ircuit
flow determines the speed of the cooling fan motor.
The fan motor runs at reduced speed until coolant
reaches approximately 165
o
F(74
o
C). The fan motor
increases to full speed (approximately 2800 RPM)
as coolant reaches 180
o
F(82
o
C).
Thefanmotor automaticallyslows downand thenre-
verses direction if coolant reaches 203
o
F(95
o
C) or
hydraulic oil reaches 212
o
F (100
o
C).
If the fan motor is stalled for any reason, the manifold
proportionalrelief valve(PRV)hasa secondary function
as a c ircuit relief to limit fan motor pressure to 3000 PSI
(207 bar).
When the engine is shut off, the over--running inertia
load of the fan blades keeps driving the fan motor and
turnsit into a pump.The check valve (CV) in the fancon-
trol manifold will open to keep the motor circuit full of oil
so the fan motor will not cavitate.
NOTE: IfPWM current is not available to the fan control
manifold proportional relief valve (PRV), the cooling fan
motor w ill run at full speed in the normal (forward) direc-
tion.
Forward Direction Fan Operation
Oilflow fromthe gear pumpis sent throughthe de--ener-
gized solenoid valve S1 to rotate the cooling fan motor.
Return flow from the motor re--enters the manifold (port
M2),through thede--energized solenoid valveS1, outof
the manifold(port T) and then is routedthroughthe mow
control manifold, oil cooler and oil filter.
Reverse Direction Fan Operation (Fig. 18)
The TEC 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 unsuitable
level or if the engine cooling fan switch is pressed to
manual reverse, a high PWM signal is sent to the PRV
valve to slow the cooling fan and direct pump oil flow
away from the fan motor. The controller then energizes
solenoid valve S1 in the fan control manifold to reverse
cooling fan motor oil flow so that the motor runs in the
reversedirection.Alower PWMsignalis senttothe PRV
valve allowingoil flow to return tothefan motor but inthe
reverse direction causing the motor and cooling fan to
run in reverse for a short time.
NOTE: The fan reversal process is not designed to
clean the radiator of debris. Refer to Operator’s Manual
for radiator cleaning maintenance recommendations.
1. Gear pump
2. Fan control manifold
3. Fan circuit supply hose
4. Hydraulic fan motor
Figure 17
1
2
3
4
Figure 18
REVERSE
FROM GEAR
TO OIL COOLER
TO RESERVOIR
TO LIFT/LOWER
CIRCUIT
TO STEERING
CIRCUIT
PUMP (P3)
FROM GEAR
PUMP (P4)
DIRECTION
PRV
G1
G2
Hydraulic
System