BRP EVINRUDE E-TEC 115 HP 2011 Service Manual page 334

TRIM AND TILT
MODES OF OPERATION (THREE PISTON SYSTEM)
Shallow Water Drive Tilt Relief
If the outboard exceeds idle RPM while operating
in shallow water drive mode (tilted up beyond the
trim range), increased pressure beneath the tilt
piston forces fluid through the tilt relief valve built
into the manual release valve.
Fluid flows from below the tilt piston, through the
tilt relief valve, and to the reservoir.
As the tilt piston moves down, the filter valve
opens and allows fluid to flow from the reservoir to
the top of the tilt cylinder.
The outboard will tilt down to the top of the trim
range.
Thermal Expansion Relief
Ambient air temperature increase can cause fluid
expansion within the hydraulic assembly. If the
fluid expands when stored in the tilt range, the
fluid under all of the pistons (and above the tilt pis-
ton) cannot expand, so its pressure increases.
If the pressure gets high enough to push the ball
of the tilt relief valve off its seat, the excess pres-
sure is vented to the reservoir.
332
2
1
1. Tilt relief valve
2. Manual release valve
3. Filter valve
3
DRC3465