Leonardo da Vinci׳s studies of friction

• This paper reports the first detailed chronological study of Leonardo׳s work on friction.
• Leonardo first stated the ‘laws’ of sliding friction in 1493.
• The widely-reproduced drawings from his notebooks date from 7–12 years later.
• His research was motivated by numerous practical mechanical problems.
• Leonardo holds a unique position as a pioneer in tribology.

Based on a detailed study of Leonardo da Vinci׳s notebooks, this review examines the development of his understanding of the laws of friction and their application. His work on friction originated in studies of the rotational resistance of axles and the mechanics of screw threads. He pursued the topic for more than 20 years, incorporating his empirical knowledge of friction into models for several mechanical systems. Diagrams which have been assumed to represent his experimental apparatus are misleading, but his work was undoubtedly based on experimental measurements and probably largely involved lubricated contacts. Although his work had no influence on the development of the subject over the succeeding centuries, Leonardo da Vinci holds a unique position as a pioneer in tribology.