Mercury 40 Service Manual page 379

Shock Function Up
Oil inside the down cavity is locked in a static position by the closed down circuit pressure
operated valve (f), the manual release valve (p) and the manifold reverse suction valve (o).
If the outboard strikes an underwater object while in forward gear, the trim rod (a) will try to
rapidly extend from the cylinder (w), the pressure increases inside the trim cylinder down
cavity and connecting passages. When the pressure increases to the level required, the im-
pact relief valves (v), located inside the shock piston (u), will open and allow the fluid to pass
through the shock piston. As the fluid passes through the piston, the trim rod (a) will extend
from the trim cylinder. The memory piston (t) is held in position by vacuum, created by the
oil in the up cavity being locked in a static position. Therefore; oil passing through the shock
piston is trapped between the memory piston (t) and shock piston (u).
a -
b -
c -
d -
e -
g -
h -
k -
m -
n -
o -
p -
q -
s -
u -
v -
w -
90-828631R3 MARCH 1999
Trim Rod
End Cap
Electric Motor
Reservoir Oil
Down Circuit Pressure Relief Valve
f - Down Circuit Pressure Operated Valve
Filter (2 shown for clarity)
Shock Return Valve
i - Up Circuit Suction Port
j - Oil Pump Gears
Down Circuit Suction Port
l - Oil Fill Cap
Shuttle Valve
Up Circuit Pressure Operated Valve
Manifold Reverse Suction Valve
Manual Release Valve
Manifold
r - Tilt Relief Valve
Tilt Relief Piston
t - Memory Piston
Shock Piston
Impact Relief Valve
Cylinder
POWER TRIM
Page 5C-17