By locking one caster wheel of a four-wheel jack against swivelling without inhibiting its ability to roll freely along a supporting surface, and by then steering an oppositely trailing or leading caster wheel with a tow bar or other suitable handle, the jack can be readily steered into tight places and under low overhanging structures even with relatively heavy loads supported thereon as the two remaining caster wheels become effective "slaves" to their respective, most laterally adjacent locked or steered wheels. The tow bar for the steered wheel and the lock for the locked wheel are readily attached to and removed from their respective wheels without the aid of tools or special fasteners.
