2001 Mercury Mariner 50-60HP Factory Service Manual, Page 321Get this manual
POWER TRIM
When the trim switch is activated in the up position, the electric motor (c) begins to rotate the oil pump gears (j), the oil pump draws small amount of oil through the filter (g) and through the up circuit suction port (i)The oil pump gear (j) rotation forces oil into the passages for the up circuitOil, under pressure, will slide the shuttle valve (m) against the down circuit pressure operated valve (f)The shuttle valve will mechanically open the down pressure operated valve, allowing oil from the down cavity of the trim cylinder, to flow into the oil pumpThis returning oil, from the down cavity, will supply most of the oil required for the up circuitOil in the up circuit is blocked from returning into the reservoir by the ball inside the down circuit suction port (k)The pressure of the oil will force the up circuit pressure operated valve (n) to open, allowing the oil to enter the passages inside the manifold (q) leading to the trim cylinder (w) up cavityOil is blocked from all other passages by the closed manual release valve (p)Oil under pressure will enter the trim cylinder below the memory piston (t)With an increasing amount of oil entering the cylinder, the memory piston contacts the shock piston (u) and forces the piston rod (a) up and out, raising the outboard motorOil on the top of the shock piston exits through passage running down along the side of the cylinder and enters the manifold passagesThe oil is drawn back into the pump (j) through the open down circuit pressure operated valve (f) and enters the pump as supply for the up circuit