An operation system for a piston-type expander includes: a first engaging member which is fixed to an output shaft of the piston-type expander, rotates together with the output shaft, and has a first slanting surface; a second engaging member which is rotatably disposed on the output shaft, and has a second slanting surface; and a drive device which, while keeping a rotation direction of the second engaging member around the output shaft fixed, moves the second engaging member in an axial direction of the output shaft to press the second slanting surface onto the first slanting surface, converts a pressing force of the second engaging member in the axial direction into a rotational torque of the first engaging member and the output shaft at a contact surface of the first and second slanting surfaces, and causes the first engaging member to rotate together with the output shaft.

An operation system for a piston-type expander includes: a first engaging member which is fixed to an output shaft of the piston-type expander, rotates together with the output shaft, and has a first slanting surface; a second engaging member which is rotatably disposed on the output shaft, and has a second slanting surface; and a drive device which, while keeping a rotation direction of the second engaging member around the output shaft fixed, moves the second engaging member in an axial direction of the output shaft to press the second slanting surface onto the first slanting surface, converts a pressing force of the second engaging member in the axial direction into a rotational torque of the first engaging member and the output shaft at a contact surface of the first and second slanting surfaces, and causes the first engaging member to rotate together with the output shaft.

An internal combustion engine includes a cylinder block defining a cylinder and a crankshaft rotatably received by the cylinder block. The crankshaft includes a crankshaft gear and is configured to rotate along a longitudinal axis of the crankshaft. The engine further includes a piston configured to reciprocate within the cylinder between spaced stroke termination points defining a stroke of the piston. The engine also includes a connecting rod operably coupled to the piston. The connecting rod includes a gear configured to engage the crankshaft gear, wherein the crankshaft gear and the gear of the connecting rod are configured to engage one another, such that as the piston travels within the cylinder, the connecting rod rotates the crankshaft via engagement between the crankshaft gear and the gear of the connecting rod.

An internal combustion engine includes a cylinder block defining a cylinder and a crankshaft rotatably received by the cylinder block. The crankshaft includes a crankshaft gear and is configured to rotate along a longitudinal axis of the crankshaft. The engine further includes a piston configured to reciprocate within the cylinder between spaced stroke termination points defining a stroke of the piston. The engine also includes a connecting rod operably coupled to the piston. The connecting rod includes a gear configured to engage the crankshaft gear, wherein the crankshaft gear and the gear of the connecting rod are configured to engage one another, such that as the piston travels within the cylinder, the connecting rod rotates the crankshaft via engagement between the crankshaft gear and the gear of the connecting rod.