Model: Q02 Gear Teeth Profiles: Four-Tooth Spur Gear With Circular Rack
Reuleaux called this pair "double pin gearing. In this system, one gear can be made with very few teeth. Hence the velocity ratio can be made very high. In this case both pitch circles become rolling circles as shown in Figure 586 of Reuleaux's 'The Constructor' 4th Edition. Thus the tooth profiles are parts of epicycliod curves. The teeth on the four tooth pinion are severely undercut with a circular arc. Such gears were sometimes used in hoisting machinery.
Francis Moon 2001-00-00