Recently I had rented a post hole digger and had the choice to either transport it in the back of the truck or tow it. I opted to tow it. The fellow and the rental place came out with this unit, which I thought was pretty slick. The wheels and axle (Figure 1 and Figure 2) stay on the machine, while the tow bar detaches.
Figure 2 shows the axel is a bolt on unit to the machine.
Figure 3 shows the detached tow bar.
The pins in Figure 4 hook into the S-shaped part of Figure 1.
The machine is then lowered so that its secondary attachment point (Figure 6) bolts onto the tow bars secondary clamp (Figure 5).
I don’t know the name of the manufacturer, but I thought it to be a slick setup.