The Unimog Dual-mode Road-Railer
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Image Gallery ( 18 images )September 20, 2006 The potential benefits of an affordable dual-mode road-rail vehicle are immense and we’ve featured previous concept vehicles in this vein from Hokkaido, Toyota (a very clever hybrid eco-friendly transit system) and Silvertip Design’s stunning Bladerunner. Now Unimog special-vehicles division has taken the wraps off a production road-railer at the Innotrans 2006 show in Berlin. Unimog’s exhibit features eight road-railer models illustrating numerous implementation scenarios on both road and rail. These include a Unimog road-railer for cost-effective shunting or manoeuvring of hauled loads of up to 1000 tonnes, a vehicle equipped with an access-platform for overhead-line maintenance and an auxiliary vehicle with crew's quarters and hydraulic equipment for rerailing derailed wagons. The vehicles are equipped with hydraulically lowerable guide wheels, with the drive on the rails being provided by the vehicle's wheels. A broad range of special railway equipment is optionally available for the Unimog road-railer, including an inductive train control system.
“In our view, the use of road-railers will become increasingly prevalent over the coming years,” explains Holger Doth, who is responsible for the road-railer segment at DaimlerChrysler AG. “That’s why we see the Innotrans 2006 show as the perfect platform for presenting our product range to an international audience of specialists.”
Advantages and capabilities of the Unimog road-railer
It uses its immense tractive power to shunt or manoeuvre heavy hauled loads, clears snow from rails and roads, grinds rail tracks, cleans tunnels, cuts clearances and maintains overhead lines. And it is highly flexible thanks to an ability to transfer rapidly between road and rail. The Mercedes Benz Unimog is capable of all this and much more. Plus it makes sound economic sense: in terms of both purchase price and running costs, it is far superior to its track-bound counterparts.
The compact design of the axle and the special-purpose wheels and rims make the Unimog ideal for use on both conventional or wide-gauge tracks (1435 to 1676 mm). On the rails, it is driven directly by the vehicle’s wheels; the guide wheels are only used to prevent derailing at speeds of up to 50 km/h. The advantage here is that the Unimog can fully utilise the high friction coefficient between the rubber wheels and the steel track. A finely graduated transmission system with eight forward and reverse gears, permanent all-wheel drive and differential locks ensure optimum transfer of the engine power (175 kW/238 hp) into maximum pulling power on the rails and enable shunting with a hauled load of up to 1000 tonnes at a speed of up to 25 km/h in both directions. A hydrodynamic torque converter, which multiplies the starting torque by a factor of 2.5, ensures smooth moving-off when towing or shunting heavy loads.
The Unimog is also optionally available with radio remote control, allowing the operator to carry out coupling and decoupling work without the assistance of a second person. Furthermore it is possible to control the Unimog from the head of the train when shunting in reverse mode, without the need for a second driver in the cab.
On-tracking made easy
The Unimog road-railer is able to quickly reach its destination by road and then transfer to the track at an embedded rail section of around five metres in length (e.g. a level crossing). As soon as the vehicle is positioned correctly, the guide wheels are lowered hydraulically – and that’s all there is to it. It takes less than three minutes for the Unimog to get ready for action on the track.
That is not the limit of this Unimog's capabilities, however; at suitable points, it can also be transferred to an open section of track. This is possible thanks to a hydraulic turntable. Furthermore, all-wheel drive and differential locks enable the Unimog to be transferred to the track even at access points in difficult terrain. After completing its work on the rails, the Unimog can be moved back onto terra firma just as quickly before being driven on to the next job site.
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