Pivot: will it or not?

It would seem that this anachronism has long been left in the past and there is nothing to remember about it. The time when you had to regularly stick around with a syringe in your hands under the chassis is long gone. However, not everything is so simple: if we talk about cars, you can really meet this node only on old cars. But, for example, quite a modern UAZ Patriot, GAZelle Business, partly Next, as well as some trucks in their design have this part. Let it be in a modified form, but the principle of its work remains the same.


How old the kingpin is, who invented it and when, is not known for certain, but it was used with might and main on horse-drawn carts. And when motor transport appeared, for a long time it was the only mechanism that guaranteed the rotation of the steered wheels.


Now this node is found on large trucks, SUVs. What is this part, how does it work, what is included in its maintenance and what was it replaced with?

What does the king pin in the suspension

By design, this is a massive metal rod around which the steering knuckle rotates. Plus, additional details: plain and rolling bearings to reduce friction, gaskets, seals in the form of rings. If the kingpin is placed on the drive wheels, then its design changes slightly: a hole is drilled in its axis through which the drive shaft passes. The main advantage of the pivot system is its strength, which ensures a solid load capacity and a long service life (with regular and competent maintenance). For example, this unit was on the Toyota Land Cruiser HZJ81. But there are also disadvantages: the massiveness of the part, which is worse compared to ball bearings, kinematics, and the need for regular maintenance.


This is not surprising: the kingpin has to work in unenviable conditions: it perceives transverse, longitudinal loads and is leaky at the same time. All dirt and sand, just water, fly onto this poorly protected part, turning into an abrasive. And, if instead of lubrication there is bare metal, the assembly will not last long.

Main types of kingpins

The most simple and reliable design has a through node. In the bridge, it passes through its lower and upper parts, where it connects the steering knuckle to the beam. The main disadvantage of such a kingpin is the possibility of its installation only in front-wheel drive cars. The element passes through the beam and therefore it is no longer possible to put half shafts or other additional elements. The through kingpin is made in the form of a narrow cylinder, a rod made of extra strong steel (the profile is the same or variable) with channels (grooves, holes) for the passage of oil. The part is fixed with a side pin.


A split kingpin connects the knuckle to the beam in two places on each side. The design here is a little more complicated: the rod has its own profile. Both the separate and through assembly are mounted using bronze (sometimes steel) bushings. Rolling bearings may also be used.

mixed designs

As the global automotive industry developed, ball bearings began to be installed on passenger cars. At first, they were looked at with skepticism: they say, these devices are unreliable. Indeed, their resource has decreased, as well as the maximum carrying capacity. Therefore, there was a “transitional” period, when a certain “hybrid” of pivots and ball parts was installed on cars. An example is the Nissan Bluebird U14 (some of its versions).


Here, the fist in its lower part is spinning on a ball bearing, and at the top there is already a king pin. Other options were also used, when the rod was equipped with hemispheres at both ends. They, in turn, were inserted into special "pits" on metal balls.

Signs of kingpin wear

Its untimely replacement can lead to sad consequences: the car will lose control. Therefore, if the following symptoms appear, it is recommended to immediately diagnose the chassis:

✅ when driving, the car pulls to the side and the tires wear out unevenly (provided that the camber / convergence is done correctly)
✅ knock when driving in the front of the suspension
✅ Steering wheel hard to turn

It is necessary to change the pivots on both sides of the axle. Increased wear of the part is typical for machines that are constantly used off-road, where there is a lot of dirt and sand.


In such cases, the frequency of maintenance should be increased. And how to extend the life of the node?

syringe

This process can be safely considered a "classic of the genre." Most trucks and cars in Soviet times (and some still) had a pivot system. For its maintenance, the purpose of which is to drive lubricant into the assembly, a syringe-supercharger (greaser, oiler) was required.


The best option is a plunger tool, but not everyone could buy (in Soviet times “get it”). Modern products of this kind are not cheap, and questions may arise about quality. By the way, working with such a supercharger is not very convenient: you have to “find” a suitable position, especially if there is no viewing hole.


Another option is the use of the so-called. Janet syringe used for catheters. True, there is a snag here: there is no tube that needs to be put on the grease fitting. The inquisitive mind of the Soviet motorist found a way out here too: a hose is taken from the bicycle pump and screwed in instead of the “zirka” (the thread fits). The second end must be cut off and inserted into the syringe.

How to lubricate the kingpin

Today, special tools are sold for these purposes. However, someone uses LITOL-24 or SHRUS-4 in the old fashioned way, which, by the way, is very problematic to lubricate through a syringe. Others prefer liquid lubricants such as TAD-17. There are even exotic options, rooted in times of scarcity. This is when graphite grease is brewed together with nigrol in a 1: 1 ratio. It's hard to say whether it's better or worse than store-bought ones. But the main thing is different: you need to inject the pivots regularly, and the frequency depends on the operating conditions.


For GAZelles, in theory, it is recommended to do this every 15 thousand kilometers, although experienced owners of these cars inject pins after 6-8 thousand km. For the Volga, these figures are even smaller: in the summer every 2-3 thousand km, and at least once in the winter months.

Will there be no more pivots?

In "mass order" this knot began to gradually "go out of fashion" for a long time - back in the late 50s. Car manufacturers decided to install ball joints that are more flexible in terms of kinematics. They do not require (or in rare cases) lubrication, they are tight. And the pivots remained mainly on powerful trucks, SUVs, and some models of commercial vehicles.


Another area of ​​​​application of the described part is the coupling device of trucks - the so-called. "saddle". It can be flanged or not, bolted or screwed. These designs do not yet have a worthy alternative. So, albeit in a modified form, the kingpin is still used to this day.