Chevy Captiva AWD
AWD “Active on Demand” – especially on Captiva – is a 4×4 system that distributes power to all wheels in accordance with the needs or road and driving conditions.
For example, if an engine produces 100 PS power, for the 4×4 system, each wheel is getting power evenly, with 25 PS. That is, the proportion of rear and front wheel to move the vehicle the same: 50:50.
With the “Active on Demand” can be changed to the proportions 60:40 or 70:30. Remarkably, to change the division, do not need to be done by the driver. The car itself that will determine, when and where to distribute power to each wheel as needed. So, deserve proud!
Distribution of torque to the wheels according to road and driving conditions, needs to be done because it could have been one of the wheels slip or not to touch the surface of the road in certain conditions. For example, slippery road surfaces or one wheel lifted.
Full vs. Part Time
Formerly, AWD or 4×4 technology, either full-time (permanent) or part-time (can be changed from x4x into 4×2 or vice versa), caused quite a dilemma.
In the “Full-Time” (FT), each vehicle is started, the engine must crank the four wheels, both in off-road or in on-road (asphalt road).
Well, the FT pavement conditions are not favorable. Fuel consumption to be wasteful. The reason, the switching component of power-driven machinery to many. Energy losses also increase.
In “Part-Time” (PT) is also a problem. The system must be equipped with a “transfer case” (some call it “the middle axle”). The task of this section, make work a 4×2 vehicle or a 4×4 course.
Some producers when i ni PT 4×4 system creates a more simple operation. The driver simply press the button to switch the system from one state to the other driving conditions. Apparently, this method is considered not practical because the weight of heavier vehicles because of the size of the middle axle big enough.
Clutch On
Well, look at the basic AWD Captiva, technically similar to the FT. The reason is, between the rear axle and the front is only connected by a coupling as permanently. There is no middle axle.
Even so, before the rear axle or differential, Chevrolet added component called “Active Coupling”. Language kitanya, active couplings. Remarkably again, the clutch is working actively on the “brain” or controlled by a computer.
Furthermore, the computer gives commands to the active clutch berdasaran information received from sensing devices or sensors mounted on a car that serves as the eyes, ears, nose, skin or other sensitive devices in humans.
After receiving the information from these sensors, computer processing and then ordered the clutch to work, in humans can be compared with the foot.
The task of the clutch went on the resulting engine torque to the rear axle. But the energy transmitted to the rear wheels, can vary according to field conditions or the road.
Clutch works when, front or rear tires slip. To make sure the tires slip one of the tires based on the difference in rotational speed of each wheel is equipped with sensors. Or it could also, the clutch to distribute torque evenly to the front and rear wheels to know, rotational speed front and rear wheels together.
For this, the system also use information from other parts, ie the engine computer, the control body (body control) and brake controls which work electronically or EBC (electronic brake control).
Clutch Magnet
Active clutch clutch consists of sheets like those used on motorcycles. Gazette clutch is also suppressed in the oil.
In the active clutch, there is another major component, which was controlled by components, namely a series of magnetic couplings (given the new electricity became a magnet). Magnetic clutch is able to transfer torque to the rear wheels from 0 to 2530 Nm.
The transfer clutch torque in accordance with instructions received from the computer or through which the surface conditions. For example asphalt, sand, mud and so on. Control performed continuously.
On smooth road conditions, the division of labor for the front axle and rear is 50:50. But if the road surface behind the slick tires or sand, the ratio changed. Torque to the rear wheels is reduced or terminated the same and only used for the front wheels. Thus, the engine power to drive large vehicles and the maximum stay.
Safer
Capabilities as mentioned above, not only helps traction and stability on sandy roads, also in wet or muddy surfaces. Fixed maximum traction on slippery roads. Similarly, the ability to climb and accelerate the vehicle from rest.
Stability is also better at high speed because the car continued to be controlled. In fact, symptoms of oversteer or understeer, can be prevented because the Chevrolet also install ESP (Electronic Stability Program) on this AWD Captiva.
Driver more comfortable working alone because this SUV is equipped with a 5 speed automatic transmission, tiptronic. Want to add workers or casual, live transmissions to touch the stick forward or backward!
Compensation of all the advantages that have been mentioned earlier, is the extra components and weight of the vehicle. When basic vehicle using front wheel motion, it is as an additional coupling components (propeller shaft), the active clutch, axle (differential) back, and an active rear axle (the wheel).
With no such component, other than add weight, rotating components also requires energy.Means greater energy consumption than degnan 4×2. This last factor is what causes Chevrolet rely on diesel engines with big torque at the last variant of this Captiva.
However, compared with the old AWD system, this latest version is much more practical light.Complex is the electronic control system.
Because the active clutch work depends on electrical energy, as well as control systems, the source of electricity in the car, the battery plus alternator must always be maintained in healthy condition and work optimally.
