Torsen-type: Automatic Torque Biasing Helical Differential
This differential is best known under the name: "Torsen diff"
The function of the Torsen Differential must not be confused with the "Limited Slip Differential" (LSD).
The Torsen differential was originally invented for front wheel driven cars, where the LSD could not be used (because the LSD will make unwanted and dangerous jerks in the steering).
The Torsen Automatic Torque Biasing senses which wheel has the better grip, and automatically biases the power to that wheel. It does this smoothly and constantly, and without ever completely removing power from the other wheel. Power is transferred automatically without the use of friction pads or plates seen in other limited-slip designs.
Unlike a conventional plate-type limited slip unit, the Torsen unit relies on gears rather than clutch plates for its operation. That means, it is much smoother in operation because, unlike a conventional plate-type LSD, it never locks harshly when the Slip-Limit is reached. Rather, it automatically biases the torque away from the spinning wheel across the axle, in a constantly varying degree.
The Torsen-ATB performs like a conventional (open) differential, until there is a loss of traction. Only then, will the torque transfer occur - when it is needed.
PRELOAD
This specific Torsen-ATB is furthermore equipped with a Preload (available in different torque settings (Preloads)). This is an extra feature added to this model.
Look at the Preload-value this way: If one wheel is in the air, you normally loose traction. But if you were using the Torsen-ATB with the Preload feature, the wheel with contact to the ground would receive torque equal to the Preload-value.
A higher Preload-value will: A lower Preload-value will:
Lift the start-point you see in the diagram, giving more Torque at zero and low Traction.
Increase the wear of the Preload-parts. Don't spin the wheels more than necessary when the Traction is < 10 %, and this will not be a problem.
Lower the start-point you see in the diagram, giving less Torque at zero and low Traction
Decrease the wear of the Preload-parts
When used in LADA Niva:
The Torsen-ATB differentials require a certain amount of resistance at the ground (i.e. traction) in order to start the torque transfer. The Torsen-ATB differential will as minimum always transfer the Preloaded torque if the spinning wheel is off the ground or on an extreme slippery surface. If spinning occurs, often a slight application of the hand-brakes, while carefully applying power, will slow the spinning wheel enough to allow the ATB differential to transfer even more torque to the other wheel.
In low traction situations, like snow and mud, the Torsen-ATB is known to perform very well.
One of the biggest advantages this Torsen type is, that it is a 'fit and forget' design:
You do not need to concentrate on when to lock and unlock, just drive and steer, the Torsen will fully automatically take control of the traction
Unlike a conventional plate-type LSD, the Torsen unit requires no special maintenance or rebuilds
Is long-lasting since there are no plates or clutches to wear out
Retains the standard method of lubrication - No special LSD-oil is required
If speed/time is important, you would be better off, with a fully automatic solution like the Torsen-ATB
The Torsen-ATB is used in luxury cars (and now available to LADA !) to improve safe driving in bad weather conditions
This Torsen differential is made in Russia.
The factory's main products are Torsen Differentials for VAZ, UAZ and GAZ.
The factory also produces batches of LSD for VAZ.
The factory holds the patent for this type of differential in Russia, and use only certified steel and staff in the production. The heat treatment of the gear-parts are also produced in batches and quality inspected before they are assembled.
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