If ever you have watched, three axles, one behind the other, being dragged instead of rolling over the asphalt in a sharp corner, then you also know just how much the tyres suffer and also where energy and wear and tear can be saved. After all, the towing machine can stand at a 90° angle to the trailer. The misery is then even worse.
Indeed, the solution offered here can also not alleviate the problem completely, an angle as acute as this is not possible for a self-steering trailing axle either. Nevertheless, the savings are immense, mainly as far as tyre wear is concerned, but also the fuel consumption is lower. Of course a great deal depends on the operating conditions. The savings on long distance haulage would, in terms of percentage, be somewhat lower that in urban delivery haulage.
Trailing axles are not exclusive to trailers and semis. Longer trucks and also buses could use them as well. In addition, they are not always self-steering, thus, they can also be fitted. Even if they are steered, when reversing they must be brought into alignment, this is done by compressed air. This is also why, after engaging the reverse gear, one should allow them a little time.
As a matter of interest, self-steering at higher speeds is not always desired, which is why, e.g., at speeds of over 40 km/h, the steering is often locked into alignment. Without this safety measure the directional stability could suffer, among other things, in the event of side-winds. Apart from this, the locking mechanism may possibly, also be used as a steering damper. 11/12