Mercury 40 Service Manual page 320

Trim Up
When the trim switch is activated in the up position, the electric motor (a) begins to rotate
the oil pump gears (n), the oil pump draws a small amount of oil through the filter, up circuit
pick-up and past the up circuit feed check ball (o). The oil pump gear (n) rotation forces oil
into the passages for the up circuit. Oil, under pressure, will slide the shuttle valve (p) against
the down circuit pressure operated valve (h). The shuttle valve will mechanically open the
down circuit pressure operated valve, allowing oil from the down cavity of the trim cylinder,
to flow into the oil pump. This returning oil, from the down cavity, will supply most of the oil
required for the up circuit. Oil in the up circuit is blocked from returning into the reservoir (t)
by the ball inside the down circuit feed check ball (m). The pressure of the oil will force the
up circuit pressure operated valve (l) to open, allowing the oil to enter the passages inside
the manifold (f) leading to the trim cylinder up cavity. Oil is blocked from all other passages
by the closed manual release valve (j) and closed tilt relief valve (k). Oil under pressure will
enter the trim cylinder below the memory piston (e). With an increasing amount of oil enter-
ing the cylinder, the memory piston contacts the shock piston (d) and forces the trim rod (b)
up and out, raising the outboard motor. Oil on the top of the shock piston exits through a
passage running down along the side of the cylinder and enters the manifold passages. In-
side the manifold the oil seats the ball (r) inside the suction valve (g), closing the passage
into the reservoir. The oil is drawn back into the pump (n) through the opened down circuit
pressure operated valve (h) and enters the pump as supply for the up circuit.
a -
b -
c -
d -
e -
g -
h -
k -
m -
n -
o -
p -
q -
s -
u -
v -
w -
90-828631R3 MARCH 1999
Electric Motor
Trim Rod
Impact Relief Valve
Shock Piston
Memory Piston
f - Manifold
Suction Valve
Down Circuit Pressure Operated Valve
i - Tilt Relief Actuator
j - Manual Release Valve
Tilt Relief Valve
l - Up Circuit Pressure Operated Valve
Down Circuit Feed Check Ball
Oil Pump Gears
Up Circuit Feed Check Ball
Shuttle Valve
Down Circuit Pressure Relief Valve
r - Check Ball
Reservoir Oil
t - Oil Reservoir
Oil Fill Cap
Shock Return Valve
Filter
POWER TRIM
Page 5B-11