So I was sitting here all day and got a little bored seeing that I have answered a few questions about lockers and such I thought maybe I would do a little write up on different rear ends so that maybe it will shine some light on them.
1. When you are driving on the street and go to make a turn one wheel will “speed up” in order to make up for the lag. With an open or limited slip (L/S) in the rear end you don’t have a problem. Now if you go and lock this same rear end then you will feel a pull, this is because one wheel is trying to get ahead of the other. This is great for off-roading or when you need complete traction but not here, you run the risk of snapping a shaft and doing greater damage to your truck.
A few definitions-
1. - Limited slip differential- The main advantage of a limited slip differential is shown by considering the case of a standard (or "open") differential where one wheel has no contact with the ground at all. In such a case, the contacting wheel will remain stationary, and the non-contacting wheel will rotate freely—the torque transmitted will be equal at both wheels, but will not exceed the threshold of torque needed to move the vehicle, and thus the vehicle will remain stationary. In everyday use on typical roads, such a situation is very unlikely, and so a normal differential suffices. For more demanding use, such as driving in mud, off-road, or for high performance vehicles, such a state of affairs is undesirable, and the LSD can be employed to deal with it. By limiting the angular velocity difference between a pair of driven wheels, useful torque can be transmitted as long as there is some traction available on at least one of the wheels.
Types- Two main types of LSD are commonly used on passenger cars; torque sensitive (geared or clutch-based or cone-based as shown in figure at top of page) and speed sensitive (viscous/pump and clutch pack). The latter is gaining popularity especially in modern all-wheel drive vehicles, and generally requires less maintenance than the mechanical type
2.- Differential locks (when engaged properly) guarantee equal wheel speed on all 4 wheels. Spinning wheels are prevented. For the rear of your vehicle if you “lock it” and drive on the street you will feel a pull, this is because one wheel is trying to get ahead of the other.
• Types- Automatic lockers lock and unlock automatically with no direct input from the driver. Some automatic locking differential designs ensure that engine power is always transmitted to both wheels, regardless of traction conditions, and will "unlock" only when one wheel is required to spin faster than the other during cornering. They will never allow either wheel to spin slower than the differential carrier or axle as a whole. The most common example of this type would be the famous "Detroit Locker," also known as the "Detroit No-Spin," which replaces the entire differential carrier assembly. Others, sometimes referred to as "lunchbox lockers," employ the stock differential carrier and replace only the internal spider gears and shafts with interlocking plates. Both types of automatic lockers will allow for a degree of differential wheel speed while turning corners in conditions of equal traction, but will otherwise lock both axle shafts together when traction conditions demand it.
o Pros: Automatic action, no driver interaction necessary, no stopping for (dis-) engagement necessary
o Cons: Intensified tire wear, noticeable impact on driving behavior (most people often tend to under steer).
Some other automatic lockers operate as an "open", or unlocked differential until wheel spin is encountered and then they lockup. This style generally uses an internal governor to sense a difference in wheel speeds. An example of this would be GM's "Gov-Lok."
Some other automatic lockers operate as an "open," or unlocked differential until high torque is applied and then they lockup. This style generally uses internal gears systems with very high friction.
• A "selectable" locker allows the driver to lock and unlock the differential at will from the driver's seat. This can be accomplished via compressed air (pneumatics) like ARB's "Air Locker" or vacuum, electronic solenoids (electromagnetic) like Eaton's "ELocker" and Nissan Corporations electric locker found as optional equipment on the Frontier (Navarra) & Xterra, or some type of cable operated mechanism as is employed on the "Ox Locker."
o Pros: Allows the differential to perform as an "open" differential for improved driveability, maneuverability, provides full locking capability when it is desirable or needed
o Cons: Mechanically complex with more parts to fail. Some lockers require vehicle to stop for engagement. Needs human interaction and forward-thinking regarding upcoming terrain. Un-skilled drivers often put massive stress on driveline components when leaving the differential in locked operation on terrain not requiring a locker.
The internal spider gears of an open differential may also be welded together to create a locked (spooled) axle; however, this method is not recommended as the welding process seriously compromises the metallurgical composition of the welded components, and can lead to failure of the unit under stress. If it is desirable to have a spooled axle, the better option is to install either a mini-spool, which uses the stock carrier and replaces only the internal components of the differential, similar in installation to the lunchbox locker, or a full spool which replaces the entire carrier assembly with a single machined piece. A full spool is perhaps the strongest means of locking an axle, but has no ability to differentiate wheel speeds whatsoever, putting high stress on all affected driveline components.
Spool- A spool rear end allows no differential rotation. A spool consists of a pinion & ring gear only, the center is solid, making the axles act as one piece. A mini-spool is similar, replacing the usual differential side gears and spider gears with a solid piece, retaining the factory differential carrier. Spool rear ends are used to achieve a similar effect to an LSD on some street and race cars. This arrangement is popular in 'drifting' where drivers aim for flamboyance rather than speed. Those that use the car for "drifting purposes" often generate their own "custom differential" by welding-solid a standard open differential to produce a homemade spool.
It is also preferred by drag racing enthusiasts for 2 main reasons. A straighter launch is achieved because power is split precisely evenly between the wheels. High horsepower vehicles with a spool generally are still aiming straight even with wheel spin. However, turning is more difficult because of the lack of the required speed differential (the outside wheel has a greater distance to travel than the inside wheel and thus has to rotate faster to compensate). They can also be made stronger, for a given size and weight. Because of the solid center design and lack of side gears, cross pin and spider gears, a spool can take much more abuse. This is especially important for drag racers that are shocking their drive trains with hard launches and sticky tires.
Well this is what I have come up with so far feel free to chime in if I missed something, or need to correct some. I used Pirate4x4, Wiki, personal knowledge to write this up.