US Patent 9132902 Marine drive system and method

An improved marine drive system for a marine vessel includes a longitudinally extending drive shaft assembly, a hydraulic cylinder and piston assembly pivotally attached between the drive shaft assembly and the vessel. The cylinder has a first fluid filled cylinder chamber that retains a coiled spring that urges a translatable cylinder piston through a second fluid cylinder chamber to extend the piston rod from said hydraulic cylinder lowering the drive shaft assembly. Fluid lines in communication with switch controlled valves allow for selective evacuation of fluid from the first fluid filled chamber to reduce fluid pressure to move the piston in response to fluid pressure in the second cylinder chamber to collapse the spring to retract the rod to raise the drive shaft assembly. An additional fluid line and switch controlled valve allows for selective removal of fluid from the second fluid filed chamber to reduce fluid pressure to move the piston in response to the spring to extend the rod to lower the subsequently raised drive shaft assembly.