That which is shown in the video above, could well be the origin of the Robson-Drive. It is the very much simplified variation of a genuine all-wheel drive, even with a certain locking effect. With the HydroDrive we've already shown one for the front axle. But of course, neither can replace all the functions of the real all-wheel drive. The Robson- Drive is suitable for all twin-axles where only one of them is driven.

Here you can see just how complicated the all-wheel drive becomes, when not only the front axle, but also the twin rear axle is to be driven. The middle axle is particularly affected, which is clearly shown below. It must guarantee that its own axle is driven and simultaneously, transfer the power to the rear axle.

This can be seen in the cut-away picture below. In the casing of the final drive, the torque is transferred through a differential gear, both to the left shaft and also passed on to a flange, which allows the connection of the Cardan shaft to the rear. The left shaft then carries a bevel gear, which meshes with a very slightly larger crown wheel. It then goes on via the differential gear to the wheels, where the rotation speed is reduced and the torque is increased. In this construction it must be noted, that the rotation speed to the wheels of the last axle does not differ.

Now have a close look at the trailing axle below. What can clearly be recognised by the image above it, is that the axle is hollow. Apart from that, it can also be hydraulically raised. If they can now, together with a driven axle and the roller working on the tyres, give additional driving force, it would of course mean an enormous weight-saving. How the connection according to Robson works, can be seen in the video below.

The manufacturers of especially heavy pickup-truck constructions are also interested in this system. What they then need, is a higher pay load or a higher permissible gross weight. This can be achieved by fitting a twin rear axle. Providing it is driven, like e.g., in the Mitsubishi L200, the Robson-construction can also transfer torque to the additional axle. Allegedly, the roller can endure speeds of up to 120 km/h, but only for a short period of course. 07/15