Not even the manufacturers of motor car trailers make everything themselves. They also make use of suppliers, e.g., for the axles, and definitely, if over 750 kgs, also the brakes. Common trailer axles are mostly rubber-sprung, if they have a total weight of 1500 to 1800 kg, they may have torsion bar- or air suspension. The rubber-springing is explained here.

Of the three axles shown in picture 1, the bottom two are without braking, the example at the top does have brakes. This one differs from the other two in that it has a flange on the trailing arm, to which the drum-brake is mounted. Basically, the construction of the axle is kept very simple, however, in the case of torsion bar- or air suspension, additional shock absorbers are absolutely necessary.

Picture 2 shows that the tandem trailer has two identical axles mounted one behind the other. It is considered to have more directional stability, can cope with heavier loads but also has a higher rolling friction. Technically seen, with the drawbar, the over-run brake mechanism and the two axles, the finished trailer is not far away. With a relatively light-weight basic frame, the drawbar must either be extended through to the rear or solid, stabilizing side-walls must be fitted.

An axle consists of a tube with a torsion spring fixed in the middle. This is made up from flat bars packaged together. The bearings of the torsion spring are, at the same time, the guide-bushings on the ends of the two swinging arms, which are fixed to these by a tapered grubscrew held by a hex-head nut.

The swinging arms have one guide-bushing each for the wheel pivots. The axle tube is joined to the trailer frame by base brackets on the right and on the left. It's insides are completely sealed from the swinging arms by means of O-rings. It has pressure lubrication points where the guide bushings can be filled with grease. 11/13