Large fly wheel is on driving shaft, small gear at its center meshes with large gear above which in turn meshes with another gear of equal size. The motion of the two connecting rods attached to these by means of crank arms, brings about a straight line drive on the piston rod. This motion is very powerful, due to the transformation of high speed to low speed. This mechanism is used where great pressure is needed and in high power pumps. It was patented by Dr. Cartwright in 1787 and was used mostly on steam engine piston rods.
[Virginia Downward & William M. Clark, 1930]

[Editor’s Note: The Cartwright mechanism was used in early steamboats to drive twin propellers in opposite directions. This model is similar to the Reuleaux-Voigt model S-34. FCM]

Francis Moon 2005-00-00