Steering & Suspension: Steering Systems: Steering arms & components
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Forward control vehicle steering

Summary
Forward-control vehicles mount the steering system forward of the front axle and steering linkage. A drag link connects the Pitman arm to a relay lever, which is connected to the track rod.
Forward control vehicle steering

In forward-control vehicles, the steering system is mounted in front of the engine and wheels. The steering box is mounted on the subframe, with the Pitman arm vertical.

A drag link transfers movement of the Pitman arm to a relay lever which has 2 arms, one connected to the drag link, and the other to the idler, by the track rod.

The longitudinal movement of the drag link pivots the relay lever. This transfers the motion through the track rod, to the idler arm, and through the tie-rods to the wheels.

In 4-wheel-drive vehicles with a beam axle, the single track rod connects the steering arms on each wheel assembly, across the vehicle.

In this design, the drag link is connected to an arm on the front of the left-hand wheel assembly. Movement of the Pitman arm is transferred through the drag link to the left-hand wheel, and through the track rod, to the right-hand wheel.

The steering box is offset from the steering column, so 2 universal joints and an intermediate steering shaft are used.

Off-road vehicles of this type, without power assistance, often use a steering damper.

It resembles a shock absorber, and operates on a similar principle. It’s mounted between the track rod and either the rigid axle, or the vehicle frame.

When the vehicle is driven over rough terrain, its purpose is to prevent shocks being transmitted through the steering linkage and back to the steering wheel.

With rack-and-pinion steering, the linkage is simpler, since the rack itself is part of the linkage. Movement of the steering wheel is transferred through the steering column, intermediate shaft, and universal joints, to rotate the pinion, which moves the rack from side to side.

A tie-rod with a ball swivel at each end of the rack relays the movement directly to the steering lever on each wheel assembly.

The rack can thus be considered as the centre track rod of a 3-piece track rod system.

The steering lever or steering arm, is linked to the tie-rod, or track rod, by a flexible ball joint that allows for suspension movement, and steering rotation.

The lever, the stub-axle and the stub-axle carrier can be forged as one piece, and can be referred to as a knuckle.

They can also be made as separate units, and assembled to form one piece.

Each steering system makes provision for adjustment of the linkage, to achieve the manufacturer’s recommended toe-setting.

The track rods or tie-rod ends are threaded, to provide for their lengthening or shortening.