Britannica Sources used in this answer

How were wheel-and-axle devices used to raise water from wells?

Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

A diagram displays six types of simple machines with labeled illustrations: inclined plane, wedge, screw, lever, wheel and axle, and pulley, each shown with real-world examples like ramps, axes, screws, seesaws, door handles, and pulleys lifting objects. — simple machine Six simple machines for transforming energy into work.

The wheel-and-axle is a simple machine that functions by using a circular frame (the wheel) revolving on a shaft (the axle) to modify motion and force. In its earliest form, this device was likely used to raise water buckets or other weights from wells.123

To perform this task, the device utilized large- and small-diameter drums mounted on the same shaft, with ropes wrapped around them. The bucket of water was attached to a rope on the smaller drum, while the operator applied force by pulling a rope on the larger drum.21

This arrangement provided mechanical advantage, which is the ratio of the force applied to the force required to lift the load. By pulling the rope on the larger drum, the operator could overcome the weight of the water bucket on the smaller drum with less effort than would be required to lift the bucket directly. The mechanical advantage in this system is determined by the ratio of the radius of the large drum to the radius of the small drum.241