Mercury 40 Service Manual page 298

SHOCK FUNCTION UP
Oil inside the down cavity is locked in a static position
by the down 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 piston rod (a) will try to rap-
idly extend from the cylinder (w), the pressure in-
creases inside the trim cylinder down cavity and con-
necting passages. When the pressure increases to
the level required, the impact 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 piston rod (a) will ex-
tend 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 be-
tween the memory piston (t) and shock piston (u).
90-852572R1 JANUARY 1998 MID-SECTION - 5D-15