Abstract: Tilt and trim cylinders have blind-end chambers connected through a main valve to a first port of a reversible pump. The rod-end chamber of the tilt cylinder is connected through the main valve to a second port of the reversible pump. The rod-end chamber of the trim cylinder is connected to an oil tank. The second port of the pump is connected to the oil tank, and the first port may be connected to either only the main valve or the oil tank through a suction-prevention valve, an orifice, or a pressure relief valve. When the pump is actuated with the tilt cylinder locked to keep an outboard engine in an tilted-up position, the trim cylinder is automatically contracted to withdraw its piston rod. Cavitation in an oil passage from the blind-end chamber of the trim cylinder to the pump is prevented when working oil is introduced from the oil tank to the pump through the orifice or the pressure relief valve.

Abstract: A filter for filtering working oil to be introduced into a gear pump is detachably mounted on the gear pump. The gear pump has a recess defined in an outer circumferential surface thereof. The filter is held in place by a filter holder. The filter holder has locking fingers engageable in the recess. The filter holder is detachably mounted on the gear pump with the locking fingers engaging in the recess.