Theory Of Operation; Power Tilt Hydraulic Diagram; Operation - Mercury 15 EFI FourStroke Service Manual

Power Tilt

Theory of Operation

Power Tilt Hydraulic Diagram

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a - Reservoir
b - Filter
c - Electric motor
d - Tilt up inlet check valve
e - Tilt down inlet check valve
f - Up circuit relief valve
g - Down circuit relief orifice
h - Hydraulic pump
i - Tilt up pressure operated check valve
j - Shuttle valve
k - Tilt down pressure operated check valve
l - Impact relief valve
m - Tilt cylinder
n - Up circuit thermal relief valve
o - Down circuit thermal relief valve
p - Manual release valve

Operation

Tilt Circuit - Up
When the tilt up circuit is activated, the electric motor rotates the hydraulic pump. As the pump's gears rotate, fluid is drawn
through a check valve and into the pump's inlet. The pump's flow passes through a check valve, then passes through a
pressure operated (PO) check valve and to the bottom of the tilt cylinder. The fluid pushes the cylinder piston out, tilting the
engine up. Oil, from the top side of the cylinder, returns through a passage in the cylinder wall to the inlet side of the pump. In
this mode, as the tilt ram extends to its limit, up pressure increases and opens the up pressure relief valve. When the engine is
not running, the outboard may be tilted to the full up position by opening the manual release valve.
Page 5B-6
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© 2018 Mercury Marine
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90-8M0125265 eng NOVEMBER 2017
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