\Ped"rail`\, n. [See {Pedi-}; {Rail}.] (Mach.)
(a) A device intended to replace the wheel of a
    self-propelled vehicle for use on rough roads and to
    approximate to the smoothness in running of a wheel on a
    metal track. The tread consists of a number of rubber
    shod feet which are connected by ball-and-socket joints
    to the ends of sliding spokes. Each spoke has attached to
    it a small roller which in its turn runs under a short
    pivoted rail controlled by a powerful set of springs.
    This arrangement permits the feet to accomodate
    themselves to obstacles even such as steps or stairs. The
    pedrail was invented by one B. J. Diplock of London, Eng.
(b) A vehicle, as a traction engine, having such pedrails.