AWD bikes
It is not really a brand new technology but the All Wheel Drive system in motorcycles never fails to evoke interest. Yamaha had launched two wheeled drive motorcycles a few years back and it enjoyed huge success in the form of a Paris Dakar victory. It was a 450cc bike and the power on the front wheel proved decisive when the riders had to tackle sand dunes and mud. It was a hydraulically driven front wheel and the power never exceeded 15 per cent of the engine’s total power.
Now, a Philadelphia based company Christini, has started marketing a two wheel drivetrain for motorcycles. The drivetrain supplies power from the engine to the front wheel of motorcycles. A second chain turns the front wheel so that riders can get through sand, snow, mud or uneven terrain more easily. The system, which was invented by Steve Christini, can be retrofitted on many off-road motorcycles and the company is looking forward to make the technology available to street bikes also. And it will sure make the ride much safer. All wheel drive holds many advantages like better control, stability, handling and cornering.
The biggest advantage for the rider is that he can avoid the front wheel from washing out from under him. As and when the washing out situation occurs, the power on the front wheel pulls it out.
The concept of all wheel drive sounds rather simple but that is hardly the case. Many large manufacturers have tried out different combinations for powering the front wheel of a motorcycle but never met with much success and so the all wheel drive system never proved commercially viable. The difficulty was in how to deliver power to the front wheel without disrupting steering and handling.
A chain fitted on one side of the hub pulls the front wheel, and hence the rider, in one direction. The hydraulic system works as proved by Yamaha but it consumes lots of power.
The Christini system has been inspired by the drivetrain of a helicopter and it has been adapted to the fork of a motorcycle. In a helicopter, the engine turns a gear. Instead of turning a chain (and a wheel) directly, that gear is attached to two other gears, which turn separate chains that then power the two rotors.
In Christini’s drivetrains, a chain runs between the main cog and gear inside the head tube. The head tube then transfers power to two separate drivetrains on the left and right of the fork. Like on a helicopter, the drivetrains spin in opposite directions, but both work to turn the wheel forward.
In ordinary motorcycles, steering is accomplished by a central bar inside the head tube. The steerer effectively connects the fork to the handlebars. Since the gears are in the head tube in the Christini system, the steerer is attached to the forks.
The system does not mean permanent two wheel drive. The drivetrain starts functioning when the front wheel and the back wheel are spinning at different speeds. When that occurs, the system begins to power the front wheel and then shuts off again after the wheel rpms equalise.
This article was taken from : indiatimes.com