英语翻译
one additional part is required to the complete a basic engine.Because it is necessary to push the piston down th cylinder more than once,in between down strokes it must be returned to the top of the cylinder.To do this,a heavy flywheel is mounted to the end of the crankshaft .When the piston is forced downed,the crankshaft turns,and the flywheel turns with it.Because the
flywheel is heavy ,it does not slow down easily.Its momentum keeps the crankshaft turning .The rotation of the crankshaft then pushes the piston back up to the tpo of the cylinder.