Study of a variable-ratio transmission
Red-chalk elliptical toothed cam driving a lantern pinion
Drawn in red chalk and oriented upside down, this sheet is a study of a variable-ratio transmission, as the e-Leo caption states. An elliptical, oval toothed wheel meshes with a small lantern pinion, so that the effective gear ratio rises and falls as the oval turns; a separate star-shaped pinion and a slender pivoting arm are sketched above. The forms are lightly drawn and partly overlap. Additional faint construction lines are present but not transcribed.
On this page
Elliptical toothed cam and lantern pinion
An oval, egg-shaped wheel is toothed around its rim and drives a small lantern (cage) pinion. Because the oval presents a changing radius to the pinion, the transmission delivers a variable ratio through each revolution.
Continuously varying gear ratio
The point of the study is that a non-circular gear changes the ratio of turning between the two shafts as it rotates, rather than holding a fixed ratio. A star-shaped pinion and a pivoting arm are drawn above as related parts.