how does an SUV that has auto4wheel drive know when to go into 4wheel drive?

Question

we have a ford escape that has atuo 4x4 and straight 4x4 .when its in auto4x4 how on earth does it know when to go into 4x4 and when to stay in 2wheel drive ?

Answer 1

The same way the ABS system works, it has wheel sensors that measure each wheels speed and it can sense when there is a difference and the wheels are spining and then it sends a signal to the electric clutch to energize and pull in the 4X4.

Answer 2

It actually doesn't go into 4-wheel drive. It's done in the transfer case with a type of heavy fluid (oil) clutch. When all wheels are spinning at the same speed everything sort of freewheels along with the main drive wheel. If that wheel starts to slip the heavy oil trys to pull the other wheels along with it giving you a boost in traction. This creates much easier driveability and less tire wear than locking into full 4-wheel drive.

Answer 3

The on board computer knows or is suppose to tell the car when to go into 4 wheel drive by reading the tires and how they are divining on the road. It's automatic.

Answer 4

Your car has sensors in each wheel that measures rotation, sensors on the brakes on each wheel, sensors on the transmission that measures engine rpm. Sensors on your steering wheel as well.

When one of the drive wheels while on 2WD starts to slip (on the Escape 2WD mode is Front Wheel Drive), the sensors detect it. Computers then check your throttle inputs. If you are accelerating and increasing power, the computer engages the remaining wheels and go to 4WD mode.

Answer 5

Auto 4x4 when two or more wheels slip a computer tells.

Answer 6

,
the anti lock brakes notice the wheel spin,
and tell the computer