Four-wheel drive is a form of drivetrain. A four-wheel drive vehicle has two or more axles, which provide power to four wheel ends. These vehicles have a transfer case, which means the front and rear drive shafts will be locked together when the four-wheel drive is engaged.
Benefits of Four-Wheel Drive
Four-wheel drive is ideal for driving in situations when there is low to very little traction. For example, if you frequently drive in snow, or take your vehicle off-road, you will greatly benefit from four-wheel drive. Some modern vehicles engage four-wheel drive automatically, so you do not have to do anything to turn it on. The automatic system normally turns on when one or more of the wheels start slipping. Other vehicles have the option of turning four-wheel drive on and off. The benefit of turning it on and off is to improve the fuel economy.
4WD vs. All-Wheel Drive
Not all four-wheel drive vehicles are considered all-wheel drive. There is a difference between the two, which we will look at. The term all-wheel drive is applied to drivetrain systems that include a differential between the front and rear drive shafts. All-wheel drive vehicles comes with anti-slip technology and work well on all surfaces. Four-wheel drive vehicles have a transfer case, which is different than the all-wheel drives’ differential. This is the main difference between the two types of drivetrains.
Problems with Four-Wheel Drive
Heavy loads that four-wheel drive vehicles carry are more likely to cause sagging springs in the suspension. These sagging springs can lead to chassis damage. If the four-wheel drive vehicle was used to pull boats or for driving off-road, there may be rust around the bottoms of the door. Four-wheel drive vehicles require more maintenance because of the extra parts, such as the differentials, transfer case, etc. Check the maintenance record to ensure these were properly maintained over time. The chassis can take a beating over time due to neglect or hard driving. Check for cracks where the chassis outriggers join the main frame. Also, check for dents or rust, which also indicates the vehicle was used roughly.
Four-wheel drive vehicles are convenient and can provide more traction on slippery roads or while off-roading. Four-wheel drive is different than all-wheel drive, so it is important to know the difference when purchasing a vehicle.
This article originally appeared on YourMechanic.com as 3 Essential Things to Know about Four-Wheel Drive (4WD) and was authored by Valerie Johnston.