hear is a reprint of a article I wrote a few years abck that may help
Traction control
A subject in itself, this is designed to be a base of knowledge to be read and clarify types of traction control and laying a base of what is what.
First let us look at why a vehicle needs a differential. Any surface you travel has a shear factor, that factor is at what point traction is lost and the surface releases the surface traveling on it, The more modern our society the more we engineer surfaces to travel our vehicles over and the more we need our wheels to have the ability to move at different speeds. Going strait down a road both wheels on an axle will turn at the same speed as they are traveling at the same speed, however throw in a curve or a bump on one side, and the wheels need to turn at different rates to keep the axle in a strait line. The lower amount of shear and the more that is needed. A vehicle on a sandy or dirt road needs it less than a vehicle on a modern highway, however manufacturers know that all vehicles will be used on a low shear surfaces and need a diff to keep parts from breaking and tires from wearing prematurely. The main reason for this is because in a turn the outside wheel needs to turn faster than the inside tire.
Most vehicles come from the factory with what is called an open differential. These were designed to let cars turn as sharply as possible. But they were not designed to use torque as efficiently as possible. A open Diff uses the least amount of torque possible. Remember torque is not constant, and a diff, open or locked transfers 50 percent of the torque to either wheel. A open diff just has to provide enough torque to get the free wheel spinning. That is all, the stuck wheel still gets the same amount of torque, but that is not enough to make it spin. Now on a paved road, that is not a problem, but in a high shear surface that means you can get a wheel spinning and go nowhere as the tire that needs more torque to turn cannot have it delivered to it as the spinning tire is dictating how much torque gets delivered to the axle.
In steps traction control, and there are a lot of types of these.
Limited slips are some of the easiest to get, A lot of factories will put these in vehicles designed to see off road or high performance on the street. Basically there are 2 different types of these, clutched or geared, they both do the same thing but differently. What is required of one is to put enough resistance on the free spinning side of a axle to develop enough torque and both sides of the axle spin at an even speed. That is why they are called
Limited slip, they may need an amount of time to react, but all in all they will and can pull a vehicle out of a lot of places others will get stuck.
Lately electronic traction controls are growing in popularity and with the advances they are making in both computer and the devices they will be our future, but until they are perfected to a level we will still be dependent on other forms. These use either the antilock brake system like the Toyota system ATRAC, or viscous couplings etc. However they work, once you have used one you see why I say the future will change everything we think of about traction control.
Lockers are the subject of today. Since we have affordable selectable lockers we have spent the last 10 years thinking they are the shiznit. The most basic form of a locker is a spool. You just remove the diff part of the axle and put in a part that locks both shafts together. No matter what both wheels will spin at the same speed. The torque developed is the amount to turn the stuck wheel. However this is why open diffs where first developed as it is not very user friendly except in high shear surfaces. Ever heard of a Lincoln locker? That is welding the diff gears together, no not the ring and pinion, the carrier ones, so that it works as a spool, popular with the low budget crowd.
Since spools have major downsides they invented the auto locker, these come in either lunchbox or full types. Lunch box lockers are usually cheaper to install and full lockers need gear setup but are normally much stronger than the lunchbox style. However your wheeling style will dictate what type you will need. Auto lockers work as a spool when you are going strait but have a built in release for turns, they are an acquired taste as the quirks they have can upset a few drivers, others love them for the simple stupid always there function they provide. I am a huge fan of Detroit Lockers.
Selectable lockers have come on strong in the last decade, with cable, electric and air controlled lockers you can have the best of both worlds, an open diff for the road and a full locked diff for the dirt. Some of drawbacks can be the support systems or the lag time they can take to kick in, but these are getting better all the time. Selectable lockers tend to cost the most, and need gearing setup, but overall they seem to be the system of choice.
So, Now if you are out in the dirt, and need both tires to turn at the same speed, weather you are crawling slowly up a rock, or have one tire in mud, you know your options and the next question will be “how do I wheel and what do I need to do that?” Traction control makes it easier to go further down the trail, and knowing how each type works will make you know what you need.
