For clarity, the figure shows the drive diagram:
- 1 - front axle differential
- 2 - rear axle differential
- 3 - intermediate differential
- 4 - cardan shaft
Operating procedure
Engine power is transmitted through the gearbox and intermediate differential directly to the front axle differential, and from it through the cardan shaft to the rear axle differential.
Intermediate differential, thanks to a complex mechanism of worm gears on a slippery road without driver intervention, automatically locks the drive.
In the usual way of driving, in dry road conditions, it distributes engine power evenly to all wheels of the front and rear axles. interrupting the traction force, it begins to automatically block these wheels, while redistributing the engine power to the wheels of the other axle, where grip is more stable.
As you can see, the distribution of drive power to the wheels is not always uniform, it depends on road conditions, primarily on the degree of adhesion of the front or rear wheels to the road surface.
The rear axle differential lock can be engaged and disengaged manually. This lock is designed primarily for smooth starting and acceleration of the car in difficult road conditions and is automatically deactivated when picking up a speed of about 25 km / h. The anti-lock braking system (ABS) is disabled during this time.
Advantages of all-wheel drive
The advantages of Quattro all-wheel drive over conventional vehicles are as follows:
Traction power
Permanent all-wheel drive significantly increases the traction power of the car, especially in conditions of snow drifts, icy conditions, when accelerating and driving uphill.
Overcoming the above conditions on the Quattro is less risky than on other car models. At the same time, this does not give the right to take risks, to try to slip through difficult sections of roads at high speed, being afraid to get stuck there. They must be crossed slowly with stops.
Acceleration (overclocking)
On slippery roads, the simultaneous four-wheel drive instead of two significantly reduces the possibility of wheel slip, improves tire grip on the road surface, and thus contributes to a faster acceleration of the car.
Driving performance
Of decisive importance for the driving characteristics of the car, especially on slippery road sections, is the rigid kinematic connection of the wheels with the road surface. In cars with a drive to one axle, with a sharp increase in speed on a slippery road, the drive wheels slip, which greatly weakens the kinematics and affects the driving performance of the car. Simultaneous four-wheel drive also increases the lateral forces of the centrifugal forces and thus increases the vehicle's stability.
Tire wear
Quattro has a probability of wheel slippage several times lower than similar models with a single axle drive. This in turn affects the timing of tire wear.
The tire wear life of Quattro under the same operating conditions is significantly longer than that of cars of the same class with two-wheel drive.
Application of winter tires
Thanks to the all-wheel drive, the vehicle remains stable on conventional series-produced tires even in winter driving conditions. At the same time, to improve driving performance and braking effect during this period, it is more expedient to use winter tires.
Application of snow chains
Snow chains enhance the traction power and braking effect of the car in winter conditions, therefore, if necessary, they can be used.
Drive system control
Unlike cars with a mechanically controlled drive system, the Quattro has all system control carried out automatically, without driver intervention. This contributes to the practical elimination of errors associated with the human factor, does not distract the driver, and helps him to focus on the overall driving.
Only the rear axle differential lock is manually disengaged, and then only if the vehicle is stuck on the road. In motion at a speed of about 25 km / h and this lock is turned off automatically.
Driving on paved roads
Permanent all-wheel drive ensures reliable vehicle stability even on wet and slippery roads.
The automatic blocking device of the intermediate differential, depending on the road conditions, the degree of kinematic grip of the wheels, timely redistributes the engine power to the axle where the grip of the wheels with the road is better and thus ensures the maximum traction power of the machine even in the most adverse road conditions.
At the same time, if it happens that the car is stuck and stopped, drive out using the rear axle differential lock. Turned on manually.
When driving at high speeds in wet weather, the front wheels of even an Audi-Quattro can lift off the road imperceptibly (aquaplaning effect).
Therefore, be careful - choose the speed taking into account real road conditions.
Moreover, despite the very good efficiency of the braking system, keep in mind that it largely depends on the degree of grip of the wheels with the road. Therefore, in rainy weather or icy conditions, do not abuse the high technical characteristics of the car, especially for a sharp acceleration to maximum speed.
Driving on unpaved roads
Remember - Quattro is not an all-terrain vehicle. Being such does not allow ground clearance. At the same time, thanks to the permanent all-wheel drive, the presence of an intermediate differential lock, it can go where other cars do not go - off-road, sand, snow, gravel, etc. Under normal engine operation, the rear axle differential lock should not be used under these conditions. It turns on only when the car is stuck or on the verge of it.
Note: The rear axle differential lock is intended primarily for starting the vehicle from a standstill and its initial acceleration in difficult road conditions. At a speed of about 25 km / h, it automatically turns off.
Below this speed, blocking can be disabled manually. If the rear differential lock is not disengaged in a timely manner, it will adversely affect the accuracy of vehicle maneuvering (for example, when parked on a dry pavement or when passing through tight, sharp curves, etc.).
At the time of engagement of the rear axle differential lock, when the wheels are directly rigidly connected to each other, the anti-lock braking system ABS is automatically disabled, since autonomous control of the braking forces separately for each wheel becomes impossible.
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