Recirculating ball steering gears is used on many trucks and SUVs today. The linkage that turns the wheels is slightly different

The recirculatingball steering gear contains a worm gear. You can image the gearin two parts. The first part is a block of metal with a threaded hole in it. Thisblock has gear teeth cut into the outside of it, which engage a gear that movesthe pitman arm (see diagram above). The steering wheel connects to a threadedrod, similar to a bolt, that sticks into the hole in the block. When the steeringwheel turns, it turns the bolt. Instead of twisting further into the block theway a regular bolt would, this bolt is held fixed so that when it spins, it movesthe block, which moves the gear that turns the wheels.

High Duty Truck recirculating ball steering gears