Abstract: Disclosed herein is a lower unit for a marine propulsion device, such as an outboard motor or a stern drive unit, which lower unit comprising a gear case including a torpedo having a fore and aft axis and including a forward portion, a central portion extending rearwardly from the forward portion and having a generally cylindrical configuration concentric with the axis and defined by a radius, and an aft portion extending rearwardly from the central portion and including a circumferentially extending cylindrical sub-portion which is concentric with the axis, and which is defined by the radius, and a circumferentially extending conical sub-portion which is concentric with the axis, which extends for a circumferential length of not more than 180.degree., and which is defined by radii which are greater than the radius and which gradually increase in the direction toward the aft end.

Abstract: A shock absorber adapted for use with the swivel bracket assembly of an outboard motor or the like, is disclosed, which swivel bracket assembly permits rotation of the motor to clear an underwater object if and when a boat strikes such an object. The shock absorber has a two stage operation in that it permits a swivel bracket assembly to rotate and provides a counterforce that is initially lower, and after some degree of rotation, preferably sufficient to have the drive shaft housing clear the object, provides a higher counterforce to continued rotation.

Abstract: A tiller arm for a marine propulsion device, the tiller arm comprising a first end adapted to be connected to a propulsion unit, a second end spaced from the first end, a longitudinal axis, and a selectively actuable switch including annular selectively deformable structure surrounding the axis, deformation of the deformable structure resulting in actuation of the switch.

Abstract: Disclosed herein is a hydraulic circuit for a marine propulsion device, which circuit comprises a sump for hydraulic fluid, a reversible hydraulic pump, a first fluid conduit communicating between the sump and the pump and including a one way check valve permitting flow to the pump from the sump and preventing flow to the sump from the pump, a second fluid conduit communicating between the sump and the pump and including a one way check valve permitting flow to the pump from the sump and preventing flow to the sump from the pump, and a mechanism for opening one of the check valves in response to closure of the other of the check valves.

Abstract: Disclosed herein is an internal combustion engine comprising first and second cylinders and first and second cylinder head cavities respectively aligned and communicating with said first and second cylinders to respectively define compression ratios respectively associated with each of said first and second cylinders, and means for providing each of said first and second cylinders with respectively different compression ratios selected to maximized the power produced in each cylinder without knocking.

Abstract: The two-cycle internal combustion engine has a sump in a lower portion of the crankcase for collecting engine fuel drains and a crankshaft bearing lubrication system including a first conduit means connecting the upper crankshaft bearing in communication with the engine intake manifold, second conduit means connecting the upper crankshaft bearing in liquid communication with the sump and having an intermediate portion or reservoir, and third conduit means connecting the crankcase in communication with the reservoir. A first check valve located between the sump and the reservoir permits fuel drains to flow from the sump upwardly toward the upper crankshaft bearing in response to a suction created in response to the low pressure or vacuum in the intake manifold and prevents backflow from the reservoir to the sump.

Abstract: Silencer apparatus for an internal combustion engine including an intake manifold, the apparatus comprising an air silencer having a lower end including a sump, and a conduit extending upwardly from the sump to the intake manifold for purging the sump of fluid only when the engine is operating.