DT-A is the prototype of an all-wheel-drive motorcycle to be used as an adventure enduro, or at rallyes. DT-A was developed over a period of 10 years. Except for a few standard-type components, such as the engine, the rear wheel including the swing arm, and the brakes, the motorcycle is our own design and product. The aim was to provide a fully-fledged additional front wheel drive for motorcycles of every performance level. Enough power should be transmitted at every speed. With normal use, handling the motorcycle should not be impaired .
The result is a motorcycle that differs strongly from a conventional design with a telescopic fork. With our DT-A the front wheel is guided by a swing arm which also brings up the transmission. In order to realize all the advantages of the concept, almost every component had to be re-designed and re-arranged, beginning with the mere frame. Thereby the DT-A can tap the ful potential in terms of lightweight design and mass centralization, after turning away from the telescopic fork. Compared to the motorcycle used for reference, the KTM 990 Adventure, the weight could be reduced by no less than 40kg .
The first test drives confirmed the excellent driving performance of DT-A, due to the reduced mass of the vehicle. The newly conceived wheel suspension did not show anything irritating. On the contrary, the suspension of the front wheel responds even more sensitively than the conventional telescopic fork.
The front wheel suspension
The front wheel is guided in a swing arm .The steering axis is spanned by two ball-and-socket joints, whereas the first one is centralized in the hub of the front wheel and the second one is positioned above the front wheel. The former is carried out as a specially developed constant velocity joint, of which the output shaft is fixly connected to the front wheel. The input shaft is lead out parallel to the rear wheel centerline and pivoted in the swing arm. It is coupled to the transmission output shaft via belt drive and chain drive. A free wheel clutch in the drive train is engaging the transmission to the front wheel automatically as soon as the rear wheel’s slip excels 5%. That means under normal driving conditions ,i.e. on tarmac, the front wheel is moving along without being driven. Not before the rear wheel loses traction, the transmission will be clutched in. With a lever at the handle bar one is able to permanently disconnect the transmission. Because of the stable purely mechanical drive train without detour the efficiency of the DT-A is very high and there are no problems deriving from energy loss at high speed / high performance
The drive joint
An ‘obvious’ cardan joint would not be suitable to transmit forces, since pulsating torque oscillations would appear with increasing steering angle. These oscillations would retroactively effect the steering and the drive train. Also the layout of automobile constant velocity joints would lead to a resetting momentum to the steering because of the high friction inside the joint. The DT-A makes use of a specially designed constant velocity joint, which transmits the driving torque with low friction. Only this development facilitates high steering angles (carried out up to 35°) without generating pulsating torque oscillations with repercussion to the steering. This constant velocity joint provides for transmission of high performance at low weight, the unsprung masses are comparable to a conventionally suspended front wheel. The steered masses are significantly lower.
Fact sheet Prototyp DT-A
KTM LC8 990 Adventure 74kW (100HP)
triangulated tubular frame, welded on a specific fixture
Fairing, seat support
Front wheel suspension
swing arm guided front wheel
Carbon unidirectional laminate
artificially aged aircraft Aluminium alloy
Dimensions and weight
Weight ready for use without fuel
Unsprung masses, front wheel, rotating
Unsprung masses, front wheel, non-rotating
27 l in 3 tanks
Suspension travel F/R
280 mm / 280 mm
Rake angel/ ground trail