In the motor vehicle area, the ball-joint was responsible for quiet revolutions, of course, out of sight, under the car bodywork. At the birth of the motor car, there were no ball-ends which could be reliably held by a socket. Apparently it's not that simple to machine a surface to last an entire working life with one precisely limited grease filling.

It all started before the motor car, with the production of ball-bearings for bicycles. In this case also, it all comes down to absolute roundness and the use of certain tricks in the assembly of bearings. In the motor car, the first ball-joints appeared on the tie-rod ends. Drive shafts still have long universal joints.

They were always bolts in bushings, first of all, without- and then fitted with needle bearings which are susceptible to failure and require servicing. The front-wheel drive had to wait a long time before it got ball joints which could transfer the torque under all conditions homogeneously. The first ones wore out very rapidly.

It quickly became clear that the sealing also played an important role. Then, roughly in the seventies, the outdated kingpins were replaced by a ball-head at the top and at the bottom (see figure 3). More than thirty years later, this would still be the case in bus front axles, on which the demands are far higher.

Figure 1 above shows an older tie-rod joint where one can still imagine what the production and assembly was like. The ball and also the ball-head part which faces the rubber, have to be particularly resistant to wear- and-tear. In this case it was mounted from the other side and securely sealed through a strong cap with a partly beaded edge.

The cap is pressed by a strong spring onto the ball-head which enables, free of play, movement in almost all directions. Still today, a cone is joined to the ball-head holding this joint together, even without a nut. As can of course be seen, someone intentionally mounted the castle-nut the wrong way round and then secured it with a split-pin.

If, by tightening the castle-nut, the cone is firmly clamped to the steering arm, one would best use a ball-joint extracting tool for removing it. It engages with the (not visible here) opening between the steering arm and the tie-rod end, by screwing down the threading, eventually the cone is levered apart.

Previously, without an extracting tool, this job was sometimes done quite grossly, using a heavy counter-brace (hammer) and knocking with a lighter hammer on the grommet, this caused the cone to eventually spring apart. Indeed, one misguided hammer blow meant that a new seal was necessary. 01/10