1995 Johnson/Evinrude Outboards 25, 35 3-Cylinder Service Manual, Page 252Get this manual
Component Description
UP CHECK VALVEWhen opened by pump pressure, it directs fluid to bottom of cylinder to move piston UPWhen opened by pump control piston, it allows low pressure fluid to return to the pump as the piston moves DOWNMANUAL RELEASE VALVEWhen opened minimum of three turns, it allows the engine to be manually raised or lowered
[] DOWN CHECK VALVEWhen opened by pump pressure, it directs fluid to top of cylinder to move piston DOWNWhen opened by pump control piston, it allows low pressure fluid to return to the pump as the piston moves UP
PUMP CONTROL PISTONMoved by pump pressure, it controls the UP and DOWN check valvesTogether, they control fluid direction and cylinder movement
[]] DOWN RELIEF VALVEOpens at approximately 1600 PSI (11,032 kPa) to protect the unit from extreme operating pressures when the cylinder is completely retracted[] EXPANSION RELIEF VALVEProtects the unit from extreme pressures caused by thermal expansion of the fluid[]] UP RELIEF VALVEOpens mechanically when the cylinder is completely extended to protect the unit from extreme operating pressures[] IMPACT RELIEF VALVESOpen under the extreme cylinder pressure generated by an underwater impact and allows the cylinder rod to extend