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While no current-era automobile front suspension incorporates a physical kingpin, the axis defined by the steering knuckle pivot points acts a "virtual kingpin" about which the wheel turns. ( July 2011) ( Learn how and when to remove this template message) Unsourced material may be challenged and removed. Please help improve this section by adding citations to reliable sources. Although the kingpin was no longer an identifiable physical component, suspension geometry was still designed in terms of a virtual kingpin along a line between the ball joint centres.
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In the 1950s and 1960s, such independent suspension became commonplace through light cars in all price ranges. The hub carrier extended vertically to span the ends of both wishbones, with a ball joint at each end. Rather than using separate pivots for both the up-and-down motion of the suspension and the steering swivel, the use of a spherical ball joint that could move in two degrees of freedom allowed the same joint to carry out both functions. This performance also encouraged the reduction of unsprung weight.
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Independent front suspension developed through the 1930s, for high-performance cars at least, often using double wishbone suspension. Kingpins were always clamped in the centre and the swivel bearings at the ends, to increase the lever arm and so reduce the bearing load. Most commonly the centre of the kingpin was fixed in the axle and the hub carrier was forked to fit over this, but some vehicles, including the Ford Model T illustrated, used a forked axle and a kingpin fixed into a single piece carrier. The kingpins were now fixed to the axle ends and the hub carriers pivoted upon them. Ackermann steering has the two advantages that it reduces tyre scrub, the need to drag tyres sideways across their tread when turning the steering, and also it reduced bump steer, suspension and road bumps tending to upset the steering direction. The beam axle between them remains fixed relative to the chassis, linked by the suspension. Some early cars also used centre pivot steering, although it became apparent that it was unsuitable for their increasing speeds.Īckermann steering separates the steering movement into two pivots, one near the hub of each front wheel. Similar centre pivot steering was used by steam traction engines, the kingpin being mounted on the 'perch bracket' beneath the boiler. This located the axle from side to side, but the weight of the wagon was carried on a circular wooden ring turntable surrounding this. Originally, with the 'turntable' steering of horse-drawn wagons, this was a single pin on which the moveable axle was pivoted beneath the wagon's frame. The term is also used to refer to part of a fifth wheel coupling apparatus for a semi and its trailer or other load. The kingpin (also king-pin, king pin and k pin) is the main pivot in the steering mechanism of a car or other vehicle. The steering kingpin at the ends of the forked beam axle on a Ford Model T
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