Toro Groundsmaster 4500-D Series Service Manual page 144

Forward Direction Fan Operation (continued)
Reverse Direction Fan Operation
Hydraulic System: Hydraulic Flow Diagrams
TO RESERVOIR
G2
G1
FROM GEAR
PUMP SECTION
g308210
(Figure
The TEC controller (T1) 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 a manual fan reversal is requested via the InfoCenter
display, 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 reverse direction. A lower PWM signal is sent to the
PRV valve allowing oil flow to return to the fan motor but in the reverse direction
causing the motor and cooling fan to run in reverse for a short time.
Note: The fan reversal process is designed to clean debris from the rear
screen but not the radiator. Refer to Operator's Manual for radiator cleaning
maintenance recommendations.
TO STEERING
CIRCUIT
M1 M2 ST
S1
50/50 FLOW
DIVIDER
CV
FD
PRV
P1 T
FAN CONTROL
MANIFOLD
TO OIL
COOLER
Figure 58
58)
Page 5–42
L
TO LIFT/LOWER
CIRCUIT
P2
FROM GEAR
PUMP SECTION
Groundsmaster ® 4500-D/4700-D
19245SL Rev A