90-826148R2 MARCH 1997 MID-SECTION - 5B-15
DOWN MODE
When the trim switch is activated in the down posi-
tion, the electric motor (a) will rotate the pump (n) in
the opposite direction. With the pump gears rotating
backwards, the flow of oil is reversed. Oil is drawn
through the filter, past the feed check ball (m), into the
down circuit oil pick–up and finally into the oil pump.
The pump feeds pressurized oil into the down pas-
sages, oil will slide the shuttle valve (p) into the up cir-
cuit pressure operated valve (l). The shuttle valve will
mechanically open the pressure operated valve and
allow oil, from the up cavity of the trim cylinder (f), to
return into the oil pump. This returning oil, from the
up cavity, will supply the oil required for the down cir-
cuit. The oil is blocked from returning into the reser-
voir by the ball (p) inside the up circuit feed valve. Oil,
under pressure, opens the pressure operated valve
(h) and enters the down passages inside of the man-
ifold (f). The manifold passage connects into the trim
cylinder passage leading to the top of the cylinder.
The cavity, inside the cylinder, above the shock pis-
ton (d) is the down cavity. As the down cavity fills with
oil, the trim ram (b) 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 pressure operated valve (l). When the trim ram
reached full travel, the oil pressure inside the down
circuit will rise until the down pressure relief valve (q)
opens, bypassing oil back into the reservoir(t). When
the trim button is released, and the oil pump stops
supplying pressure, both of the pressure operated
valves (h & l) will close and; if open, the down pres-
sure regulating valve (q) will close. The closed
valves will lock the fluid on either side of the shock
piston (d), holding the outboard motor in position.
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