POWER TRIM
90-857046R1 NOVEMBER 2001 Page 5B-15
Down Mode
When the trim switch is activated in the down position, the electric motor (c) will rotate the
pump (j) in the opposite direction. With the oil pump gears rotating backwards, the flow of
oil is reversed. Oil is drawn through the filter (g), through the down circuit suction port (k)
and into the oil pump (j). The pump forces pressurized oil into the down passages. Oil will
slide the shuttle valve (m) into the up circuit pressure operated valve (n). The shuttle valve
will mechanically open the up circuit pressure operated valve and allow oil, from the up cavity
of the trim cylinder (w), to return into the oil pump. This returning oil, from the up cavity, will
supply the oil required for the down circuit. The oil is blocked from returning into the reservoir
by the ball (i) inside the up circuit suction port. Oil, under pressure, opens the down circuit
pressure operated valve (f) and enters the down passages inside of the manifold (q). The
manifold passage connects into the trim cylinder passage leading to the top of the cylinder.
The cavity, inside the cylinder, above the shock piston (u) is the down cavity. As the down
cavity fills with oil, the piston rod (a) retracts into the cylinder, lowering the outboard motor.
Oil from the up cavity exits the cylinder and is drawn back into the pump through the open
up circuit pressure operated valve (n). When the piston rod reaches full travel, the oil pressure
inside the down circuit will rise until the down pressure regulating valve (e) opens, bypassing
oil back into the reservoir. When the trim button is released, and the oil pump stops supplying
pressure, both of the pressure operated valves (f & n) will close, and if open, the down pressure
relief valve (e) will close. The closed valves will lock the fluid on either side of the shock piston
(u) & memory piston (t), holding the outboard motor in position.
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