How a Eaton G80 locker works

Auto Tech: Locking differentials

Eaton G80 locking differential. Click image to enlarge

By Jim Kerr; photos by Chris Chase



Drive axle, rear axle, differential: they are all terms we use when describing the unit that directs the engine’s power from the transmission to the tires. Differential may be the best term to use, because the drive wheels have to turn at different speeds when the vehicle goes around a corner. The differential allows this. It also splits the torque to the drive wheels, which is great when the tires are on good traction surfaces, but put one wheel on ice or loose dirt and you can easily become stuck. That’s where Eaton’s locking differential comes in useful.

Locking differentials lock both wheels together when additional traction is needed. This is usually done on rear axles only, because locking the front axle makes it very difficult to steer. Mercedes G500’s have offered an electric locking front axle, and combined with the locking rear axle, it is perfect for getting the vehicle over fallen logs and out of deep mud holes, but switch it off if you want to turn.

Dana and Eaton are two manufacturers of locking axles. Both have been around for decades. You can find Dana locking axles in a variety of larger trucks and delivery vans. They are designed for heavy-duty use and they have been used in everything from Canada Post delivery vans to one-ton Dodge trucks. Eaton has been making locking axles for both light duty and heavy-duty vehicles since 1973, and you only find them in GM vehicles.

Eaton recently demonstrated the advantages of a locking differential in a rear-wheel drive pickup over even the best four-wheel drive system and four wheel traction control. The vehicles were positioned with one wheel on dry pavement and the other rear wheel on a set of rollers to simulate a start with one wheel on ice. An object placed in front of one front wheel simulated driving up a curb or out of a rut. Then the driver attempted to drive each vehicle away.

Without a locking axle, the wheel on the rollers would spin but the vehicle wouldn’t move. Even with traction control, which brakes the spinning wheel to cause torque to transfer to the other side, there wasn’t enough traction to cause the vehicle to climb over the obstacle.







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