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Steering linkage
Along with their use of different gear sets, steering systems also use different steering linkages - the system of connecting parts and pivots between the steering gear and steering arms.
In rack-and-pinion systems, the steering linkage consists of two inner tie rods and two tie rod ends covered by rubber boots to protect their assemblies from dirt and debris. The inner tie rods attach to the steering rack ends, while the outer ends attach to the suspension arms on the steering knuckles. This setup connects the rack directly to the steering knuckle.
Recirculating ball-type steering gears require a more complicated linkage to transmit the rotary output of the sector shaft to the back-and-forth movement of the wheels. In most steering linkage arrangements, one end of the center link is supported in the Pitman arm, while a frame-mounted idler arm supports the other end. The idler arm pivots in a support attached to the frame when the steering linkage moves back and forth.
The center link connects to the tie rods, which connect to the steering arms. In these setups, the steering arms are part of the steering knuckle spindle assemblies. When the steering arm moves, the steering knuckle assembly rotates on the suspension control arm ball joints.
Most rear-wheel drive vehicles and pickup trucks with recirculating ball steering have a special linkage setup called parallelogram linkage. This linkage features a center link that always moves parallel to the axle. Parallelogram steering linkages may be mounted either on the front or rear of the vehicle.
Tie rods are used in linkages for both steering systems because of their movement capabilities. Tie rods are ball and socket devices. A spring or plastic spacer holds the ball in position in the socket, while the ball attaches to a tapered stud. The tapered stud fits into a taper in a steering arm and is held in position by a threaded nut. The ball and socket allows up-and-down movement between the tie rod and the steering arm as the vehicle goes over bumps. Tie rod length is adjusted via threaded sleeves, which are locked by clamps.
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