Hydraulic power trim and power tilt system supply

Abstract

A hydraulic system for a combined power trim and shock absorbing piston-cylinder unit of an outboard motor includes a reversible pump having a trim-up port connected by a pressure responsive pilot valve piston cylinder units and a trim-down port through a reverse lock solenoid valve and a down-pilot spool valve providing full drain flow for trim-up and power flow for trim-down. An 'up-reverse' pilot valve with a pressure operator is in parallel with the reverse lock valve and provides a restricted by-pass for limited trim-up in reverse. The trim-up hydraulic input or powered side of the cylinder units define a trapped hydraulic system creating 'memory' in the system so after impact the motor returns to the original trim position. The return side permits relatively free-flow to permit 'trail-out' under low impact. At high speed impact, the flow is restricted and cylinder pressure increases. At a selected point, a shock valve within the piston-cylinder opens and absorbs the shock forces. The piston unit includes an inner floating head telescoped into a head secured to the piston rod with a chamber thereby formed to store the liquid flow during shock movement. A metered orifice and check valve allows return to the original trim-set position.