A differential locker (or diff locker) forces both wheels on an axle to spin at the same speed, regardless of traction differences, effectively providing maximum power to both wheels.
Here's a breakdown of how they work:
What is a Differential?
Before understanding a diff locker, it's important to know what a differential does. In a vehicle, the differential allows the wheels on the same axle to rotate at different speeds. This is crucial when turning, as the outside wheel has to travel further than the inside wheel. A standard or "open" differential achieves this by allowing torque to flow to the wheel with the least resistance.
The Problem with Open Differentials in Low-Traction Situations
In slippery or off-road conditions, an open differential can become a liability. If one wheel loses traction (e.g., is on ice or in the air), it will spin freely, and very little, if any, power will be sent to the wheel with traction. This is because the differential always sends equal torque to both wheels, and the wheel spinning freely requires almost no torque.
The Solution: A Differential Locker
A diff locker overcomes this limitation by essentially locking the two axle shafts together, forcing them to spin at the same speed. This ensures that if one wheel loses traction, the other wheel will still receive power, allowing the vehicle to move.
Types of Differential Lockers
There are two main types of differential lockers:
-
Automatic Lockers:
- These lockers engage automatically when one wheel loses traction and begins to spin faster than the other.
- They typically use internal mechanisms, such as gears or clutches, to detect wheel slip and lock the axle shafts together.
- Once traction is regained, the locker may disengage automatically, allowing the wheels to differentiate again. Some require one wheel to spin faster for disengagement.
- Examples: Detroit Locker, Automatic ratcheting lockers
-
Manual Lockers:
- These lockers require the driver to manually engage and disengage them, usually via a switch or lever.
- They offer more control over when the differential is locked, but require the driver to anticipate when locking is needed.
- Examples: Air Lockers (ARB), Electric Lockers (Eaton E-Locker)
How Each Type Works in More Detail:
| Type | Engagement | Disengagement | Mechanism | Advantages | Disadvantages |
|---|---|---|---|---|---|
| Automatic Locker | Automatic (Traction Loss) | Automatic (Traction Regained or Wheel Speed Difference) | Gears, Clutches | Simple operation, always ready when needed | Can be noisy, unpredictable on-road handling |
| Manual Locker | Driver Controlled | Driver Controlled | Air Actuation, Electric Solenoid | Driver control, predictable handling, selectable | Requires driver input, must remember to engage/disengage |
When to Use a Diff Locker
Diff lockers are typically used in off-road situations where traction is limited, such as:
- Mud
- Sand
- Rocks
- Snow
- Ice
They can also be helpful in certain on-road situations, such as when one wheel is stuck in a ditch or on ice. However, it's important to use diff lockers with caution on paved roads, as they can negatively affect handling and tire wear.
Potential Drawbacks of Using a Diff Locker on Paved Roads
- Reduced Steering Control: Because both wheels are forced to spin at the same speed, turning can become difficult, especially at higher speeds.
- Increased Tire Wear: Forcing both wheels to spin at the same speed on pavement can cause tires to scrub and wear unevenly.
- Driveline Stress: The locked differential puts additional stress on the axles, gears, and other driveline components.
- Harsh Ride: Ride quality and handling can suffer significantly.
In summary, a diff locker enhances traction in challenging conditions by forcing both wheels on an axle to rotate at the same speed, overriding the differential's normal function. Choosing between automatic and manual lockers depends on driving style and intended use. It is crucial to understand their impact on on-road handling and maintenance.
