This section is from the book "The Home Cyclopedia Of General Information", by Charles Morris. Also available from Amazon: Home Cyclopedia of Necessary Knowledge.
[L.] The rubbing of one body against another. It may be caused by a sliding motion or a rolling motion. Friction clutch or coupling is an engaging or disengaging gear for revolving shafts, pulleys, etc.; they being so pressed together as to revolve in company. Friction-wheel transmits motion by surface friction instead of by teeth.
 
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