A wheel assembly comprising a wheel 80 mounted on a bracket 92 wherein the bracket 92 is rotatable about an upwardly extending axis 82 and a locking mechanism controlled by a solenoid to selectively prevent rotation. The solenoid may be a latching solenoid such that no power is consumed in its rest positions and a spring may be provided to bias it towards the locked position. The bracket 92 may have opening into which a locking member can selectively extend and the opening may be surrounded by a guide surface which slopes downwardly such that movement up the slope works against a biasing force. The wheel 80 may be used on a stretcher and with a remote activation device provided on a handle. Also disclosed is a lifting mechanism with cross members engaging rails and coaxial actuators for pivoting support members.
