A powered load-moving tractor unit for moving a wheeled load comprises a tractor body with two powered ground-engaging tractor wheels steerable by a tiller and a draw bar for connecting the tractor body to the load through a releasable load hitch. To steer the load, the tractor body can be moved pivotally about a vertical axis relative to the draw bar. That vertical axis is defined by the two halves of a turntable mounted on the tractor body directly over the axis of rotation of the steerable ground-engaging wheels. The draw bar is rigidly connected over the top half of the turntable and extends down the front of the tractor body to the load hitch. The load hitch comprises telescopically inter-engageable elements on the draw bar and the load, and a latch mechanism that is remotely releasable from the end of the draw bar remote from the load hitch.