1911 Encyclopædia Britannica/Axle
AXLE (in Mid. Eng. axel-tre, from O. Norweg. öxull-tre, cognate with the O. Eng. æxe or eaxe, and connected with Sansk. áksha, Gr. ἄξων, and Lat. axis), the pin or spindle on which a wheel turns. In carriages the axle-tree is the bar on which the wheels are mounted, the axles being strictly its thinner rounded prolongations on which they actually turn. The pins which pass through the ends of the axles and keep the wheels from slipping off are known as axle-pins or “linch-pins,” “linch” being a corruption, due to confusion with “link,” of the Old English word for “axle,” lynis, cf. Ger. Lünse.