Eaton MLocker Differential Turns 50

Eaton MLocker differential. 

Eaton's Vehicle Group is celebrating 50 years of MLocker differential production. The mechanical locking differential provides drivers with best-in-class traction without the need for pushbuttons, shift knobs, or other driver intervention, and is applicable to vehicles with both internal combustion engines and electrified vehicles (EVs). 

“We’re happy to celebrate this important milestone for the MLocker differential, which is built on the success of its predecessor, our popular Posi differential,” said Mark Kramer, business unit direct, ePowertrain, Eaton’s Vehicle Group. “The unique design and proven quality of the MLocker differential have made it the differential of choice for global full-size pickups and sport-utility vehicles, and even a recently launched electrified urban truck in the Asia-Pacific region.”

Utilizing a self-contained, automatic engagement mechanism, the MLocker differential engages in low-traction situations when a wheel speed difference (compared to the other rear wheel) of 100 revolutions per minute (RPM) or greater is detected. Automatic locking takes less than a fraction of a second, improving traction and providing the driver with increased safety and confidence when traveling on wet or icy roads, gravel, mud, and dirt. The MLocker differential is also compatible with existing anti-lock brake and vehicle stability systems, which simplifies OEM integration.

During normal driving conditions, the MLocker differential functions as a light-bias, limited-slip differential. When a low-traction situation occurs that causes a wheel speed difference, a flyweight mechanism opens to engage a latching bracket, triggering a self-energizing clutch system until both axles turn at the same speed (full lock), thereby preventing further wheel slip. Unlocking occurs automatically and the differential resumes normal operation.

The MLocker differential has undergone modifications over its long production run, but the foundational design and concept have remained constant. 

“Functionally it’s the same design, but we have made a lot of improvements over the years. Our initial concept has weathered the test of time, although it’s been consistently improved to meet the needs of the industry,” said Keith E. Morgensai, an engineering specialist who has been involved in MLocker differential engineering and evolution for more than 40 years.

“It’s deceptively simple, but there is an awful lot of engineering that went into its development,” Morgensai said.

Since launching the MLocker differential, Eaton’s Vehicle Group has continued to add to its differentials portfolio that offers solutions for all user profiles.