Today's article will focus on a rotary engine with reciprocating piston movement and a rotating crankcase. Since we are talking about a rotary engine with reciprocating piston movement, we will not discuss the Wankel engine, even though it belongs to the group of rotary engines, because its rotary piston revolves around an eccentric shaft.

We will, therefore, be interested in a completely different type of engine, which is a rotary engine, the pistons of which perform a reciprocating movement and whose crankcase rotates (rotates) together with the entire engine.

A multi-shaft engine is a type of piston internal combustion engine equipped with multiple crankshafts. The multi-shaft construction enables the realization of single-piston, two-piston (engine with counter-rotating pistons), and multi-piston engines.

A multi-shaft engine is always equipped with more than one crankshaft. According to the number of shafts, this motor is more precisely called, for example, a two-shaft motor, a three-shaft motor, a four-shaft motor, and so on.

A reciprocating internal combustion engine is a type of combustion engine equipped with a piston, the task of which is to mediate the conversion of thermal energy generated by a chemical reaction into the mechanical work of the engine.

Under the term piston combustion engine, we can imagine a classic engine with reciprocating motion of the piston or a less used engine with a rotary piston and thus the Wankel engine.