Patent ID: 7931513

Claim:
A marine propulsion system comprising: a power source to generate rotary force; a propeller driven by the power source; a shift position switching mechanism located between the power source and the propeller, having a first hydraulic clutch and a second hydraulic clutch to connect and disconnect the power source and the propeller, and to be switchable among a first shift position in which the first hydraulic clutch is engaged and the second hydraulic clutch is disengaged so that the rotary force from the power source can be transmitted to the propeller as a rotary force in a first rotational direction, a second shift position in which the first hydraulic clutch is disengaged and the second hydraulic clutch is engaged so that the rotary force from the power source can be transmitted to the propeller as a rotary force in a second rotational direction which is opposite the first direction, and a neutral position in which both the first hydraulic clutch and the second hydraulic clutch are disengaged so that the rotary force from the power source cannot be substantially transmitted to the propeller; an oil pump to generate hydraulic pressure; a first valve located between the oil pump and the first hydraulic clutch to open and close communication of oil between the oil pump and the first hydraulic clutch; a second valve located between the oil pump and the second hydraulic clutch to open and close communication of oil between the oil pump and the second hydraulic clutch; a third valve located between the oil pump and the first and second valves to open and close communication of oil between the oil pump and each of the first valve and the second valve; and a control device to control the first valve, the second valve, and the third valve.