A peritrochium is the wheel component in a classic wheel-and-axle lifting mechanism, historically known as an axis in peritrochio. By wrapping a rope around the larger circumference of the wheel and another around the smaller axle, a small force applied to the wheel can lift a heavy load on the axle. This arrangement provides a mechanical advantage proportional to the ratio of their radii.
Heard on the job
The textbook demonstrates how the peritrochium reduces the effort needed to raise the load.
Insider tip
You will rarely hear this word on a shop floor, as engineers simply refer to the assembly as a wheel and axle.