hamaxopodes

HAMAXO´PODES(ἁμαξόποδες), in Latin ARBUSCULAE, appear to have been cylindrical pieces of wood, placed vertically, and with a socket cut in the lower end, to receive the upright pivot fixed above a wheel or above the middle of the axis of a pair of wheels, which could thus turn horizontally in every direction. One use of this sort of socket was to unite the axis of the fore-wheels of a chariot to the body (ἁμαξήποδες, Pollux, 1.144, 253; ἁμαξίποδες, Hesych. s. v.); another use of it was to attach the wheels of a testudo to the framing in such a manner that the machine might easily be moved in any direction: in fact, the arbuscula and the wheel together formed a castor or universal joint (Vitr. 10.20, s. 14.1, ed. Schneid.). Newton (ad loc.) supposes that, for the latter purpose, a single piece of timber would be both clumsy and insufficient, and that the arbuscula must have been a sort of framing. (See his figure, No. 114; Ginzrot, Wagen und Fahrwerke, 1.91, fig. 3.)