In the late 1960s, LEGO introduced a steering mechanism to some of the Legoland series of vehicles that used a special set of pieces to give the front wheels some range of movement.
The system was made up entirely of specialized parts with the exception of the printed 1×2 brick that was used as a handle at the top.
A typical combination is shown below, as it was used in the 730 Steam Shovel with Carrier set from 1973.
A rod (part 799) connected the special wheel holder brick (part 800) through a tongued vehicle base (part 804 in this model), then through two plates modified with a hole near the center (parts 709 and 711 here). The rod and wheel holder are usually inventoried on Bricklink as the complete assembly 799c800.
The underside of the vehicle base was molded with a space to hold the two small pegs on the top of the wheel holder. This controlled the range of movement to keep the wheels from rubbing on the sides of the model. In practice, this system didn’t hold up to heavy play and the wheel holders are often found with one or both of the pegs sheared off, as shown on the black wheel holder below.