System, All Wheel Drive, abbreviated AWD have long been used to improve patency of the crossovers on the roads and in adverse weather conditions.
They can be responsible for the distribution of torque from the motor to the wheels front and rear axles. This driver is often installed on machines with a leading dash.
While the rear axle is finds connect on demand when there is a slippage of the front wheels. This system is divided into mechanical and electronic control. And in this lies the main difference.
In the “mechanical” system uses the center differential. For example, with a Torsen limited-slip works on the basis of the changing friction of mechanical parts, which leads to a redistribution of the torque between the axles. This type of drive is distinguished by improved reliability and performance even under heavy loads. And of the minuses is possible to allocate the inability to intervene in the operation of the actuator driver and the relatively slow speed of response.
In electronically controlled actuator for transportation of the unit to the rear wheel meets the center clutch with the clutch pack, which is under the control of the electronics shrink, which leads to a redistribution of torque to the rear axle. In a similar type of drive electronics evaluates many factors: wheel slip, the speed of the unit, steering angle and more. Because of this, the accuracy of the allocation time increases.
The comfort of use of this system is that variations in its operation can be set. Because of many crossover drivers have the opportunity to adjust the programme of work of a full drive, making fine-tuning it to the peculiarities of the road surface: sand, dirt, rocks or wet grass. Other advantages of electronically controlled systems, it is possible to highlight the precision and rapidity, low fuel consumption and less load on the motor as on a good road system applies to traffic only to the front axle.
However, have similar systems and problems: for example, it is not equipped with a next lower gear, and the role of the locking cross-axle differentials imposed on the stabilization system and traction control ABS.
On top these systems are not designed to withstand loads and harsh environments.