POWER TRIM AND TILT 8-21
TRIM/TILT “DOWN” CIRCUIT
When the PTT switch is operated “DOWN” position, the electric motor and gear pump will operation on
counterclockwise direction.
Check valve B will open; oil will flow from reservoir to spool valve A.
It makes spool valve B move to downward, then “UP” pressure main check valve 2 open.
Oil in the lower chamber will return to pump, and then oil pressure will rise and open “DOWN” pressure main
check valve 1, then oil will flow to upper cylinder chamber of cylinder.
It makes the piston rod push down and the engine will tilt down.
To keep oil level, oil flows from reservoir to pump through the check valve B.
Surplus oil in the pump through the “DOWN” relief valve 3 and returns to reservoir.
When trim motor stops, both the “DOWN” pressure main check valve 1 and the “UP” pressure main check
valve 2 will close to retain tilt/trim position.
In the trim area, trim piston and floating tube are moving with piston rod.
When full trim/tilt “DOWN” position is attained, sustained operation of the “DOWN” relay will have no effect, as
pump oil flow will be returned to the reservoir through the “DOWN” relief valve 3.
Oil reservoir
Tilt cylinder upper chamber
Trim cylinder upper chamber
Trim piston
Free piston
2-way valve
Spool valve
Check valve
Check valve
Spool
valve
“DOWN” pressure main check valve
“UP” pressure main check valve
“DOWN” relief valve
Gear pump
Floating tube
Lower cylinder chamber
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