An “L-shaped” bushing assembly having a retainer pin sleeve and axle sleeve. An “L-shaped” retainer pin is fitted to the retainer pin sleeve and provides a handle piece that projects through the walls of the bushing assembly and wheel that is maneuverable to retract and release the retainer pin and wheel from a grooved axle. The L-shaped retainer pin and bias spring are alternatively mounted in single and multi-channel slots to facilitate retainer pin mounting and/or containment of the retainer pin at a storage position. The retainer pin sleeve slots and/or a transverse open slot facilitate cooperation of a wheel removal tool with the retainer pin(s).