King pin angle, virtual or physical, is sometimes referred to as it's acronym KPA, or alternatively king pin inclination (KPI), or steering axis inclination, SAI. This virtual king pin angle remains a fundamental design parameter. While no current-era automobile front suspension incorporates a physical king pin, the angle of the pivot points of the steering knuckle constitute a "virtual king pin" about which the wheels turn. Unverifiable material may be challenged and removed. Please help improve this article by adding citations to reliable sources. This section does not cite any references or sources. The nipple at the front of a semi-trailer to connect to a fifth wheel coupling on a tractor unit is also known as a kingpin, which usage is analogous to the original horse-drawn wagon and traction engine steering use. (The functionally analogous, similar looking and very robust joint between the chassis and boom on a backhoe is however referred to as a king post.) Dana produced the king pin version of the D60 axle until 1991. 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.Īlthough they are largely obsolete, kingpin suspensions have the advantage of being able to carry much heavier weights, which is why they are still featured on some heavy trucks. ![]() ![]() 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. ![]() 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. Any replacement part needs to be reliable enough that the vehicle can be used in the usual situations with confidence.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. ![]() While Morrisman may know that the pins were soft and needed to be checked every say 500 km, or know not to get airborne in the vehicle because the landing shock is too much, a future owner or even someone else driving the vehicle on loan may not. In this case while it may be tempting to not harden and grind the pins (or even use a less suitable material), it has potential safety impacts. As an example, when I set up my grinders, even though they are 3 phase from a VFD, I set pulley ratios so that if the VFD was removed by a future owner in say in 50 years time the wheels will not run over speed. If you are making vintage vehicle kingpins from EN36A do they still need to be hardened and ground?.It's individual preference of course, but when looking at using/ making a replacement part that is used in a situation that is safety (or even function) critical I always try to make it so that the part does not become an unknown weakness.
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