Four-wheel drive systems use a transfer case to lock the front and rear axles together, splitting power equally. This setup maximizes traction in severe off-road conditions, deep snow, or mud. Because the axles are locked, driving a traditional part-time system on dry pavement causes driveline binding and tire scrub.
Heard on the job
Make sure the customer knows not to engage 4WD on dry highway pavement or they'll grenade the transfer case.
Also heard as
- four-wheel drive
- four-by-four
Do not mix it up with
- 4x4: 4WD refers to the drivetrain mechanism, while 4x4 refers to the entire vehicle having four wheels and four driven wheels.