Mercury 45 Jet 50-55 Service Manual page 309

Maximum Tilt
With the piston rod at maximum travel, and due to no
rod movement, the pressure inside of the trim cylinder
(w) will increase to the pressure required to move the
tilt relief piston (s). The tilt relief piston's "pin" opens
the tilt relief valve (r). Up pressure flows into the trim
relief passage, and returns back into the reservoir.
90-817643R1 DECEMBER 1996 MID-SECTION - 5E-11