The most common type of steam winder is the two-cylinder double-acting horizontal engine driving direct on the drum shaft. These engines, which are made with cylinders up to 42 in (1.1 m) in diameter and with a 84-in (2.1-m) stroke, possess the merit of simplicity and ease of control. The two cylinders act on cranks set at 90 degrees to each other and are large enough for either to start the engine from rest against a full load, since one may happen to stop at dead center (i.e., with the piston at the end of its stroke, in which position it can exert no turning moment on the crank).