| Anyone that's driven their 4WD over uneven | | | | loses traction and begins to spin faster than the |
| terrain has likely experienced "wheel slip" -- a loss | | | | other, the clutches engage on the non-moving |
| of traction caused when one front and one rear | | | | axle shaft and equalize the torque applied to both |
| tire loses contact with the ground. The result was | | | | shafts therefore restoring traction. These types |
| an immobile vehicle with its ungrounded tires | | | | of LSDs work great on the street or for getting |
| spinning twice as fast as they normally do while | | | | out of mud. Their downfall is that they need to |
| the grounded tires remained firmly in place doing | | | | spin very fast for the clutches to engage. This will |
| nothing. The reason for this is because of the | | | | eventually cause the clutch plates to wear out |
| axle's differential which, under normal driving | | | | and require replacing. In addition, they typically |
| conditions, transmits equal torque to both wheels | | | | require a special lubricant for the clutches. Popular |
| on the axle yet allows them to rotate at different | | | | products in this line are the Detroit Tru Trac, |
| speeds (such as when turning a corner). This is | | | | Eaton Posi, and Auburn Limited Slip. |
| accomplished with an internal unit of gearing | | | | Light-duty and Heavy-duty Lockers |
| referred to side gears or spider gears. The | | | | These are often the preferred choice over |
| remedy for this traction loss is to "lock up" these | | | | clutch-type LSDs. Just like the above mentions |
| gears thus forcing both tires to rotate in unison. | | | | units, these also replace the side and spider gears, |
| This is accomplished with a limited slip differential | | | | however they're replaced with ratcheting-style |
| (LSD) commonly referred to as a locker or | | | | teeth. This allows the vehicle to be street |
| locking differential. There are many types of LSDs | | | | driveable, yet offers superb off-road |
| available. This article will explain their differences. | | | | performance. This provides a tolerable medium |
| Spools | | | | for drivers that want a locking differential, but still |
| A spool is not technically a locker, but its ultimate | | | | do the majority of their driving on streets. These |
| purpose is to function as one. A spool is a unit | | | | types of lockers offer great performance for |
| that replaces the differential's side and spider | | | | their price, and are likely the most popular type of |
| gears essentially creating a solid axle. This forces | | | | locker in off-road use today for that reason. |
| both tires to always spin at the same rate. The | | | | Popular products in this line are the Detroit Locker |
| advantage of this is guaranteed traction, but it | | | | and E-Z Locker by Tractech, Lock-Rite by |
| comes at the expense of premature tire wear if | | | | Powertrax, and the Quick Lok by Genuine Gear. |
| the vehicle spends most of its time on pavement | | | | Air Lockers, Electric Lockers, and Manual Lockers |
| because one tire will always "skid" when turning | | | | These are the most advanced types of LSDs |
| sharp corners. It's also important to make sure | | | | because offer both the comfort of an open |
| each tire has equal air pressure or they will wear | | | | differential with the ability to fully lock at the |
| down unevenly and cause a loss in fuel economy. | | | | driver's control. Air lockers utilize compressed air |
| A spool is not typically recommended unless the | | | | to lock the gears, electric lockers use an electric |
| vehicle will spend the majority of its life driving | | | | solenoid, and a third kind uses a cable for |
| off-road where traction is essential (especially for | | | | engagement. These types of LSDs are the most |
| rock crawling, mud, and steep hills). A spool is the | | | | expensive, however consumers should be advised |
| least expensive way to professionally lock the | | | | that they get what they pay for. They offer |
| axle. | | | | superb performance in any situation whether |
| Trac Locs and Limited Slips | | | | on-road or off. Popular products in this line are the |
| These are units that utilize a series of clutches | | | | ARB Air Locker, Eaton E-Locker, Auburn ECTED, |
| that engage against the side gears. When one tire | | | | and OX Locker. |