Question

The engine's changes up-and-down motion into rotary motion?

Answer 1

The crankshaft changes up and down or __ motion of the piston into a more readily usable __ motion. the reduction in volume and increase of pressure of the air or combustible mixture in the cylinder prior to ignition, produced by the motion of piston toward the cylinder head after intake.

Answer 2

James Watt was urged by Boulton to invent some form of rotary motion for his steam engines. The idea was to replace the reciprocating action of the original. In 1781 he did just that. His so-called sun-and-planet gear provided the motion by means of which a shaft produced two revolutions for each cycle of the engine.