HYDRAULIC CYLINDER FOR A PROPULSION UNIT OF AN INBOARD OR OUTBOARD MOTOR

摘要

A hydraulic cylinder serving as a tilting unit for a propulsion unit of an inboard or outboard motor is pivotally connected to the hull of a boat and its associated piston rod is pivotally connected to the propulsion unit. In order to act as a shock absorber when the propeller strikes an obstacle the piston (4) is formed with an oil hole (7) having a check valve (8). The effect of possible leakage through the check valve (8) is overcome by the provision of a disc valve (13) having two concentric annular elastic sealing members and biased by a spring (14) against a cover plate (17) formed with holes (18) and constituting one face of the piston (4). The space between the sealing members is thus in communication with the end of the oil hole (7) and the disc valve (13) thus operates in series with the check valve (8) to prevent leakage of oil during operation.