POWER TRIM AND TILT 9-15
Upper cylinder chamber
Lower
cylinder
chamber
"UP" pressure main check valve
"UP" relief valve
"DOWN" pressure
main check valve
Spool valve
PTT motor
Oil reservoir
Tilt rod
Piston
Gear pump
Check valve
PRINCIPLES OF OPERATION
TRIM/TILT “UP” CIRCUIT
The electric motor is operating in a clockwise direction. Check valve A will open, allowing oil to flow from the
reservoir to the pump. Oil flow from the pump enters the spool valve, moving it to the left, opening the “down”
pressure main check valve and returning oil from the upper cylinder chamber (plus oil from the reservoir) to
the pump. Pressure built up by the pump will then open the “up” pressure main check valve and oil will enter
the lower cylinder chamber.
When trim motor stops, both the “DOWN” pressure main check valve and the “up” pressure main check valve
will close to retain tilt/trim position.
When full trim/tilt “up” position is attained, sustained operation of the “up” relay will have no effect, as pump oil
flow will be returned to the reservoir through the “up” relief valve.
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