4WD vs 2WD: The Differences Between Part-Time, Full-Time, Automatic & AWD

4wd-jeep-wrangler-unlimited.jpg It can be confusing to know when to use the four-wheel drive in your Jeep and when not to — especially if this is your first 4WD vehicle.

For starters, it will help if you know what the differences are between the various types of drive systems, particularly Jeep four-wheel drive systems.

This is especially true since there is a lot of confusion surrounding the terms 4WD, 2WD, Part-Time 4WD, Full-Time 4WD, Automatic 4WD, All-Wheel Drive, and what it means to shift on the fly.

Following are detailed explanations of these types of drive systems and how they work…

 

How Four-Wheel Drive Works

Many people think that 4×4 means all 4 wheels are driven at the same time. But this isn’t necessarily the case.

When your vehicle negotiates a bend in the road, the differential in the axle compensates for the fact that the outside wheel travels farther than the inside wheel does. Therefore, it allows a speed differential to exist between the 2 wheels.

Since energy always takes the easiest route, the differential abides by the laws of physics in this case.

So, if one of your wheels is on a slippery surface (like ice) then all of the energy will be sent to that wheel and away from the wheel that currently has good traction. However, as a result, you will lose all forward motion!

When 4WD mode is engaged on your Jeep, the front and rear axles are locked together, so at least one wheel on each axle can be driven by the engine effectively.

You can force a 4×2 vehicle to act similar to a 4×4 by gently pressing the brake pedal. This slows down the wheel that’s spinning and transfers energy to the wheel that has traction.

Read: Is it time you got a four-wheel drive Jeep?


Types Of Drive Systems

4wd-jeep-wrangler.jpg

Your Jeep will have one of these configurations. You should know which type of Jeep 4×4 systems yours has. There are pros and cons to each.

The following information will also be helpful if you’re trying to understand how four-wheel drive works, or how other vehicles differ from yours based on their drive systems:

 

  • 4×4 (4WD) – The first figure is the number of wheels. The second figure is the number of “powered” wheels. 4WD is commonly used to describe a vehicle with four-wheel drive.

    Jeep’s official 4×4 glossary of terms.

     

  • 4×2 (2WD) – As with 4×4, the first figure is the number of wheels. The second is the number of “powered” wheels. However, with 4×2, engine power is transmitted to only 2 wheels — usually the rear wheels. 2WD is commonly used to describe a vehicle with two-wheel drive.

    Owning A 4×2 Jeep – An Oxymoron?

     

  • Part-Time 4WD (PT 4WD) – This refers to a four-wheel drive system that operates on-demand and drives all 4 wheels by locking the front and rear axles together via a shift lever. It usually includes 2 speed ranges (Hi and Lo). Part-time 4WD systems must be operated in 2WD mode on dry pavement, because they’re designed to be used only in special situations when extra traction is required.

    How To Use Part-Time 4WD

     

  • Full-Time 4WD (FT 4WD) – This is a four-wheel-drive system that can be operated continuously on all surfaces. It powers all 4 wheels at all times. A full-time 4WD system may include the option of part-time operation (allowing you to shift into 2WD on dry pavement, for example) and may or may not have Hi and Lo speed ranges.

    Full-Time 4WD vs Part-Time 4WD

     

  • Automatic Four-Wheel Drive (Auto 4WD) – A drive system that automatically engages 4WD as needed. When internal monitors sense differences in individual wheel speeds (indicating that a tire is slipping), then 4WD is automatically engaged.

    The Difference Between AWD and Automatic AWD

     

  • All-Wheel Drive (AWD) – A full-time single-speed system designed to supply drive power to all 4 wheels consistently. The percentage of front/rear power delivery varies from system to system.

    How To Choose An AWD Vehicle vs A 4WD Vehicle

     

  • Shift on the Fly – A drive system that allows manual shifting from 2WD to 4WD Hi without coming to a stop. Most drive systems have a recommended speed limit at which you can engage the system. Typically, it’s below 60 mph.

    Check out Jeep’s official 4×4 basic FAQs

 

Lynnette Walczak

I like to help people find unique ways to do things in order to save time & money -- so I frequently write about "outside the box" ideas that most wouldn't think of. As a lifelong dog owner, I often share my best tips for living with and training dogs. I worked in Higher Ed several years until switching gears to pursue things I was more passionate about. I've worked at a vet, in a photo lab, and at a zoo -- to name a few. I enjoy the outdoors via bicycle, motorcycle, Jeep, or RV. You can always find me at the corner of Good News & Fun Times as publisher of The Fun Times Guide (32 fun websites).

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Fun From Around the Web

  • http://www.19994runner.com/ 19994Runner

    for a starter on 4WD, it is advised to find the difference between the 4WD systems that are being made by the Japanese. The figure 4×4 is not obvious to many people. The first figure defines the number of wheels total while the second one defines the number of them attached to the engine.

  • Jack

    NEVER FORGET-FWD goes better in snow. BUT -it doesn’t STOP any better.When I had a pushbutton 4wd, I only used it when I was I was STUPID (to get me out).No snow in Nayarit Mx. ie: 2wd (unless lotsa mud). THINK y drive smart. Jack