4x4 Vehicles, Diff Lock and Traction Control

Question

Please explain the difference between having central diff lock in a 4x4 compared to having central diff lock + traction control. Would the vehicle with only the central diff lock be able to go on the same terrain as the vehicle that have both. What about axle twisters.

Answer

A very interesting question, because I think that not a lot of people without the experience and knowledge will know the answer.

All permanent 4x4 vehicles, such as the land Rover Defender 110, Land Cruiser SUV’s  and a few other models have a central differential as well, to compensate for the possible “wind-up” that would have occurred between the front and rear axels if there was no centre differential, as part of the   gearbox. With the central diff-lock engaged you will have a 50/50 distribution of power to your axels, but in an “axel-twist situation it is still possible that your 4x4 will stand still, should one wheel each on the two axels (on either sides of the vehicle, i.e. left front and right rear), lose traction and will simply spin, with the opposite wheel on each axel standing dead still.  Now this is where traction control will come in handy! The vehicle will detect when traction is lost and will use the ABS Braking system to brake the spinning wheel and in the process transfer power to the wheel on the opposite side of the axel that has good traction. That is why some of the traction control systems on the market is noisy, because of the ABS doing its thing to get you through obstacles and in particular, axel-twisters.

A 4x4 driver that is competent and have good throttle control,  with a vehicle fitted with traction control, can drive almost the same places as 4x4 drivers with vehicles fitted with front and rear differential locks! Inexperienced drivers sometimes “tap –off” the throttle when they feel or hear that there is a little bit of wheel spin, where the computer need to pick up the wheel spin, in order to activate the traction control. So good throttle control is essential for the traction control to work optimal.

To answer your question, no, a vehicle with only a centre diff-lock will not be able to drive the same terrain as one with traction control as well. You will need a lot more momentum to get the vehicle through obstacles, which might result into lots of wheel spin, which is bad for the environment and is a huge contributor towards erosion.

Hope that answer your question.

Regards

Andre Botha (4x4 Overland Tour Guide & Assessor GP 3431)
Just 4x4 Adventures