|wheel and axle|
|a simple machine for raising weights in which a rope unwinding from a wheel is wound onto a cylindrical drum or shaft coaxial with or joined to the wheel to provide mechanical advantage|
wheel and axle
basic machine component for amplifying force. In its earliest form it was probably used for raising weights or water buckets from wells. Its principle of operation is demonstrated by the large and small gears attached to the same shaft, as shown at A in the . The tendency of a force F applied at the radius R on the large gear to turn the shaft is sufficient to overcome the larger force W at the radius r on the small gear. The force amplification, or mechanical advantage, is equal to the ratio of the two forces (W:F) and also equal to the ratio of the radii of the two gears (R:r).
Learn more about wheel and axle with a free trial on Britannica.com.