Four Wheel Drive Notes
Notes: Four Wheel Drive
FourWheel Drive
Lets start with the oldschool version. 4WD, sometimes also referred to as Four by Four, or
4×4, is typically used on offroad vehicles – or at least vehicles with offroad pretensions.
There are as many versions of 4WD as there are words in this article, so I am going to stick to the basics in explaining it.
Power goes from the transmission to what is known as a transfer case. This snarl of gears splits power between the front and rear axles so that maximum torque is going to each wheel.
It was good enough to beat the Nazis, and it’s still good enough to hurl your Jeep over a big pile of rocks. Despite its heroic heritage, however, it has some problems.
When the transfer case splits power evenly, it ensures that each wheel turns at the same speed. This is deeply problematic when doing things like turning. You see, for a car to make a turn, the inside wheel has to turn more slowly than the outside wheel, which is covering more ground. If the vehicle can’t do this, the inside wheel loses traction and it spins freely. This, as you might be able to guess, isn’t great for moving forward efficiently.
There are a couple of ways that modern 4WD systems get around this. For starters, most modern 4WD systems are only on when you activate them. This can be done electronically or by using that weird secondary level that usually sits forgotten next to your coffee cup. That way, you can use 4WD at low speed in snow or mud, but enjoy the drivability of regular twowheel drive in normal conditions.
The other, more refined 4WD systems are activated with buttons or switches, rather than a rudimentary lever, and include multiple settings for the 4WD system. These systems usually have a 4WD ‘High’, which splits power less evenly and allows what’s called ‘limited slip’ between the inside and outside wheels. This corrects the locked, spinning inside wheel problem to a point. Typically, however, High 4WD is recommended
FourWheel Drive
Lets start with the oldschool version. 4WD, sometimes also referred to as Four by Four, or
4×4, is typically used on offroad vehicles – or at least vehicles with offroad pretensions.
There are as many versions of 4WD as there are words in this article, so I am going to stick to the basics in explaining it.
Power goes from the transmission to what is known as a transfer case. This snarl of gears splits power between the front and rear axles so that maximum torque is going to each wheel.
It was good enough to beat the Nazis, and it’s still good enough to hurl your Jeep over a big pile of rocks. Despite its heroic heritage, however, it has some problems.
When the transfer case splits power evenly, it ensures that each wheel turns at the same speed. This is deeply problematic when doing things like turning. You see, for a car to make a turn, the inside wheel has to turn more slowly than the outside wheel, which is covering more ground. If the vehicle can’t do this, the inside wheel loses traction and it spins freely. This, as you might be able to guess, isn’t great for moving forward efficiently.
There are a couple of ways that modern 4WD systems get around this. For starters, most modern 4WD systems are only on when you activate them. This can be done electronically or by using that weird secondary level that usually sits forgotten next to your coffee cup. That way, you can use 4WD at low speed in snow or mud, but enjoy the drivability of regular twowheel drive in normal conditions.
The other, more refined 4WD systems are activated with buttons or switches, rather than a rudimentary lever, and include multiple settings for the 4WD system. These systems usually have a 4WD ‘High’, which splits power less evenly and allows what’s called ‘limited slip’ between the inside and outside wheels. This corrects the locked, spinning inside wheel problem to a point. Typically, however, High 4WD is recommended