A king pin is a unit designed to move the steering wheel of a car within the limits set by the steering mechanism. A spherical hinge is the cornerstone of the pivot.
In the modern sense, the pivot is a structural element of the wheel swivel mechanism, designed to give it the required degrees of freedom. This concept unites mechanisms of different design, united by a common purpose. In one form or another, the kingpin is part of almost all wheeled vehicles.
Development of the design of pivots
Initially, the pivot was a rod on which the common pivot axis of the front pair of wheels of the horse-drawn carriage was fixed. When the first cars appeared, the pivot was understood as an individual pivot axle, on which a wheel was mounted using a pair of roller bearings.
Since the middle of the 20th century, the traditional design of the pivot mechanism for turning car wheels has been replaced by spherical and hemispherical hinges. This solution made it possible to simplify the design of the pivot, allowing, due to the presence of one element, to ensure both the rotation of the wheel and its rotation. The wheel turns in accordance with the driver's control signal via the steering gear.
Application on modern cars
Modern spherical hinges of pivot parts have increased reliability and the ability to work for a long time in intensive mode without intermediate lubrication. The pivots of this design are widely used as suspension elements for off-road vehicles and carrying capacity. They are used in slewing gears in trucks, pickup trucks and off-road vehicle parts. Driving performance of the vehicle depends on such characteristics of the king pin as pitch and roll angles.
When a noticeable backlash appears in the pivot pair, the unit requires replacement. The cause of wear can be driving on roads with poor-quality or damaged surfaces, lack or leakage of lubricant, imbalance of wheels. The replacement king pin is supplied as a separate assembly unit, the design of which is individual for each vehicle. Grease is put into the contact cavity of the king pin.
In cars of new designs, a MacPherson-type suspension is used, the design of which allows the wheels to perform pivotal movements due to the mobility of the shock absorber. In this case, the pivot is called the imaginary axis of the wheel, around which it turns according to the driver's control signal.
