1987 Johnson/Evinrude CU Outboards 35A thru 55 Service Manual, Page 305Get this manual
Stem ValveThis valve provides positive seal in the tilt cylinder through the trim rangeTrim Down Pump Relief ValveThis valve controls oil pressure in the system during tilt and trim down operationThis valve also balances the volume of oil between the top of the hydraulic cylinders and the bottom during down operationTiltTrim Check Valve valve checks fluid at the base of the hydraulic cylinders and prevents leak downIt also allows oil to flow from the pump to the underside of the tilt and trim cylinders during the trim out and tilt up operationReverse Lock Check Valve This valve allows oil to flow from the pump to the top sides of the tilt and trim cylinders during trim in and tilt down operationIt also allows oil flow to return to the pump during trim out and tilt up operationIt also acts to prevent the motor from tilting up during reverse running of the enginePump Control PistonPump oil pressure moves to open the reverse lock check valve during tilt up and trim out operation and opens the trim check valve during trim in and tilt down operationThis piston must be centered between the abovementioned valves when the pump is not pumping CD -This