Australian Car Guide

Rubery Owen Powered Trailer and Land Rover Forward Control 101".

The Land Rover 101" and Rubery Owen powered trailer make a six wheel drive combination. More details of this particular vehicle, which is a prototype, can be found at http:// 4wd.sofcom.com/ Mil/ LandRover/ FC101/ prototype.html. It was originally brought to Australia for Army trials in the 1970's, but has long since been fitted with a mini-bus body for outback tours.

The trailer has a Land Rover axle complete with differential and, in this case, free wheel hubs. Its propeller shaft can be seen beneath the trailer tow bar.

The production 101 uses the LT95 transmission with full time four wheel drive and centre differential as found in the original Range Rover. The LT95 was designed with the 101 and powered trailer in mind and permits the use of a "hot shift" power take off (PTO): this PTO rotates at the same speed as the prop-shafts regardless of whether hi-range or lo-range is selected. The trailer therefore does not need its own transfer case.

Prototype 101's came with a part-time four wheel drive system and could drive the powered trailer only in lo-range.

The towing point is mounted in the centre of the 101's rear chassis cross member. A conventional army style tow hook (left) can be fitted for use with ordinary trailers and other army vehicles. The tow hook is attached by the chain which carries teeth to latch over a flange on the chassis cross member and another on the hook thus clamping them together. Releasing the wing nut allows the chain to be unwrapped to detach the tow hook and its flange.

Removing the conventional tow hook reveals the power take off drive. Inside this socket is a splined drive shaft which supplies the power, taken from the transfer case PTO unit via a propeller shaft, to the Rubery Owen trailer.

Forces between the 101 prime mover and the trailer, which can of course include both pushing and pulling, are transmitted through a flange on the trailer coupling which is locked in place by the chain mentioned before.

The powered trailer cannot use any ordinary tow bar, instead it carries a fitting to lock into the power take off drive socket. The trailer's drive shaft passes down the centre of this fitting which must articulate relative to the trailer. A yoke on the trailer allows 60 degrees of movement in pitch and yaw and 360 degrees in roll (not recommended).

Land Rover conducted various experiments with powered trailers using simpler, more conventional tow bars which had more restricted movements but they were felt to be insufficiently "soldier proof".

The drive shaft must contain one or more joints to allow for changes in angularity between the 101 and the trailer. Twin universal joints are used. Taken together, these effectively form a constant velocity joint which would be important at large angles of deflection or high speeds. This arrangement also allows for some "play" in the tow bar yoke.

The 101 with trailer forms an articulated six wheel drive (6WD) which has some advantages over a rigid one. It is almost impossible for the unit to get "cross axled". In fact the trailer almost always has its full weight sitting on its wheels regardless of terrain and is most unlikely to loose traction. In comparison, a four wheel drive that happens to get supported on diagonally opposite wheels can loose traction, unless axle diff' locks are fitted, because one wheel on each axle is unweighted.

For whatever reason, the powered trailer did not go into volume production. Cost may have been an issue as it is certainly complex. There are also reports of it causing roll overs: If the combination is jack knifed, the trailer can exert a strong side-ways push on the 101 at a height of nearly three feet and this can be sufficient to roll the latter in some conditions.

- © L. A11ison

Another trailer, showing the drive and also a rather "rough" yoke.

Go to the Land Rover FC101 and FC101 prototype pages

Thanks to Mike Ford and Rod Genn for providing pictures and information.