Abstract: A steerable axle assembly having an axle with a generally vertically extending bore therein, a kingpin that is non-rotatably positioned in the bore in the axle in such a manner that the kingpin is longitudinally engaged by the bore so that the kingpin can not drift upwardly in the bore, the kingpin having upper and lower cylindrical portions that receive first and second tapered roller bearings, respectively, the first and second tapered roller bearings being retained, respectively, in apertures in upper and lower yoke arms of a steering knuckle. The first and second tapered roller bearings are adjustably preloaded by an externally threaded bearing adjuster that is threaded into an internally threaded portion of the aperture in the upper yoke arm of the steering knuckle.