2 Wheel Drive and its roots (in Englisch)
What has proved successful in the car world is now a reality in the motorcycle world! 2WD for motorcycles has just as many advantages as 4-wheel drive on cars. Yamaha recently introduced their 2WD TT600R to the media, and this revolutionary dirt bike got a great response from the journalists who tested it. After racing a 2WD TT600R in several rallies from Sweden to Sardinia, the bike has proved to be superior to conventional models, particularly under difficult conditions, such as on mud, sand, gravel and wet surfaces.
How does it work?
Yamaha’s 2WD system is, like most good ideas, quite simple. A hydraulic pump driven from the gear output shaft delivers hydraulic pressure to a small motor built into the bike’s front wheel hub. The system is light, has no mechanical parts and can be used on virtually any standard chassis .
How does it drive?
The beauty of the Yamaha 2WD system is that it is totally automatic - the rider does not need to adjust it or turn it on and off. Power is only applied to the front wheel when the rear wheel starts to slip, and the amount of power delivered to the front wheel increases and decreases according to the amount of slip being experienced at the rear wheel. It is a self-regulating system which allows you to ride the machine almost like any "normal” motorcycle. But unlike a conventional off road motorcycle which often corners with a sliding rear wheel, the Yamaha 2WD system allows the rider to go around corners in a much more accurate line. In addition to its more efficient cornering, this system also increases straight line stability – and because the 2WD system substantially improves traction, the machine will accelerate faster than a conventional motorcycle on a slippery surface. Yamaha believe that this 2WD system has many benefits both in the Enduro world and also in other areas.
Go wherever you want
Just imagine, with 2WD you can explore difficult off-road terrain that you would never dare go on your standard Enduro bike! And you would be able to go places where most conventional one-wheel-drive bikes would get stuck. Since 2WD pulls as well as pushes the machine through corners, you will not experience rear wheel sliding - in the most extreme conditions you will just experience a controlled slide with both wheels. This system undoubtedly offers many advantages in all riding conditions, and would be particularly advantageous on wet roads and on slippery surfaces such as cobblestones.
Chronology of 2WD development
Yamaha Motor Europe initially studied 2WD back in 1992. First of all the company considered the more obvious mechanical systems such as shaft or chain drive to the front wheel. However, after initial testing it became obvious that mechanical front wheel drive was not a realistic solution. These systems were just too heavy and also suffered from high frictional losses that soaked up too much of the machine’s power output. In addition to these problems the shaft and chain drive designs adversely affecting the motorcycle’s steering characteristics, and so development of a mechanical 2WD system was shelved. YAMAHA then commissioned Öhlins to develop a prototype hydraulic drive system.
Based in Sweden, Öhlins is a part of the Yamaha Group, and has extensive experience with hydraulics for shock absorbers and other applications.
The Swedish engineers soon came up with a simple but effective solution using a compact hydraulic drive unit, and in 1998 two YZ250 motocross machines equipped with 2WD entered the Swedish National Gotland Rally, where Yamaha test rider Torleif Hansen won his class on one of the new 2WD prototypes.
The next success for Yamaha’s new system came at the Sardinia rally, where the Italian Belgarda Yamaha Team entered a 2WD TT600R. Again the machine won its class with rider Antonio Colombo, demonstrating the enormous potential of the new system.
More in the future
It is no wonder that Yamaha’s product planners are already thinking about the many different applications for 2WD in the near future, and some Enduro models would undoubtedly benefit from the system. Have a look at the illustrations. Just imagine how these concepts would set new benchmarks in the world of motorcycling!