Locking Differentials
What is a locking differential?
Locking differentials (generically referred to as “lockers”) can lock the axles together to provide 100% of available torque to the wheel with traction. During turns, a locking differential operates like an open differential - the wheels can rotate at different speeds. However, when traction is needed, the axles can be mechanically locked together forcing the wheels to rotate at the same speed. This is especially helpful in off-roading situations when one wheel is off the ground or on an otherwise very low traction surface. When locked, the wheel in the air doesn’t receive any torque because there is no traction and the wheel on the ground receives all the torque, allowing the vehicle to move.
Eaton makes several locking differentials, including the ELocker, Detroit Locker, and MLocker.
How do locking differentials work?
Automatic locking differentials:
Like the name says, automatic locking differentials require no driver action and automatically lock the axles together when torque is applied.
Some, like the Eaton MLocker, (commonly found on GM pick-up trucks and SUVs) normally operate as an open diff, and lock automatically upon loss of traction (under 20 miles per hour), then unlock when conditions allow.
Others, like the Detroit Locker, are normally locked, automatically unlocking during turns and re-locking when conditions allow.
Driver-selectable locking differentials:
Driver-selectable locking differentials require the driver to activate a switch, usually located on the dash, which activates the locking mechanism. Some lockers use a lever and cable to lock the axles together.
Eaton ELockers use a simple pushbutton and electromagnetic assembly to actuate the engagement collar, which locks the axles.
Others use air (known as air lockers) and utilize a vacuum diaphragm to actuate the clutch, which locks the axles. These have some added installation complexity and cost due to the required air compressor and airline plumbing.
Are there any disadvantages to a locking differential?
Some lockers are known for being noisy and harsh on the street, with sometimes unpredictable impacts on handling, especially in corners and wet/ice/snow conditions, but the ability to have fully locked axles is worth those trade-offs for some drivers. These types of lockers are primarily used in racing situations.
Drop-in or “lunchbox lockers” replace the stock spider gears or limited slip clutches with a locker section and are an easy to install, lower cost option. However, they are not as strong as a traditional locker because they rely on the OEM carrier and reliability could become an issue if power adders, larger wheels and tires, and other modifications are made to the vehicle.
