Mercury 40 Service Manual page 328

Shock Function Up
Oil inside the down cavity is locked in a static position by the closed down circuit pressure
operated valve (h), the manual release valve (j) and the tilt relief valve (k). If the outboard
strikes an underwater object while in forward gear the trim rod (b) will try to rapidly extend
from the cylinder , the pressure increases inside the trim cylinder down cavity and connect-
ing passages. The rise in pressure will seat the check ball (r) inside the suction valve (g),
preventing fluid from returning into the reservoir. When the pressure increases to the level
required, the impact relief valves (c), located inside the shock piston (d), will open and allow
the fluid to pass through the shock piston. As the fluid passes through the piston, the trim
rod (b) will extend from the trim cylinder. The memory piston (e) is held in position by vacu-
um, created by the oil in the up cavity being locked in a static position. Therefore; oil passing
through the trim rod piston is trapped between the memory piston (e) and shock piston (d).
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-19