What is the Differential Lock in a Tractor and How to Use it?

What is the Differential Lock in a Tractor and How to Use it?

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Like most things, you don’t realize you need them until you do. There are a decent number of arguments about choosing a tractor with a differential lock versus not having one and getting it cheaper but not as effective on off-road tracks, mud, or even snow. Now, what is the importance of the differential lock on a tractor and how does it work?

In a tractor, a differential-lock is a device inside the differential that allows both axles to be locked together. Just do this on extremely slippery surfaces. Tractors use locking differentials to maintain traction, particularly when driving on soft, muddy, or rough surfaces. 

A lot of agricultural and military vehicles have lockers. On some farm tractors, the operator may step on a pedal with his or her heel to lock the differential as required.

Today, we explore the importance and function of the differential lock on tractors, and how they impact its performance in sticky situations. We should understand its capabilities and limits. Without further ado, let’s begin and let me tell you an interesting story.

An individual purchased a high horsepower tractor 1500 miles away because it was much less expensive. It was discovered after the arrival that it lacked a differential lock and only lasted a week because it couldn’t pull a load in the hills, so it was sold and moved to a flatter country. In the end, it was not a good deal; it costs more than buying what the local vendors had. So, is it worth it or a waste of money?

What is the differential lock in a tractor?

What is the Differential Lock in a Tractor and How to Use it?

For serious off-road driving, locking differentials are considered necessary equipment. Many of these vehicles have a locking differential on the central differential (between the front and rear axles), the rear differential, or some combination of the three.

The differential lock is the component that transfers torque from the driveshaft to the wheels through a series of gears. It is applied to the wheel with the least amount of resistance. The wheels are driven independently to allow the vehicle to turn smoothly without tire binding and causing chirping. If you start from a complete stop and one of the tires is on a metal cover, this is evident. The vehicle would have a slight tendency to lurch forward.

On tractors which is a farm vehicle with the power and traction to automate agricultural activities, mostly tillage, but now a wide range of tasks. If the differential lock is installed it will enable the vehicle to be unstuck from snow and ice. With the introduction of all-wheel drive and numerous 4WD features, the differential lock has fallen out of favor.

It’s typical for at least one wheel to slip or lift in the air while driving on an especially uneven or slick surface. This is where the “wheel of least resistance” comes into play for us 4x4ers. The diff recognizes that the wheel spinning wildly in the air or on a slick surface is much easier to rotate than the one firmly gripped to the ground. As a result, the wheel with the momentum that could force us out is rendered powerless, while the opposite wheel spins ineffectively.

This is where the all-powerful diff lock comes in handy! The diff is “locked” and starts to drive both wheels equally when the diff-lock is engaged, whether factory standard or aftermarket. This not only causes the wheel with no traction to continue spinning in the hopes of finding traction, but it also allows the well-grounded wheel to drive.

In a tractor, the differential allows the driving wheels to have different speeds. When spinning, this is important because the outer wheel moves faster than the inner. They would literally “burn rubber” if they were chained together and forced to travel at the same pace. 

One wheel will often slip and lose traction before the other when pulling a heavy load. The differential lock will slide a pin through the differential, stopping one wheel from spinning while the other has no traction. You get more pulling power by locking both axles together, but you can’t switch the tractor. That’s why you only use the differential lock when it’s necessary.

The differential aims to allow the wheels to turn at different speeds so that turning is easier and the grass isn’t ripped up when you’re on a slick surface. However, the same feature will cause one wheel to spin, effectively turning your tractor (or truck, or whatever) into a one-wheel drive vehicle (assuming you’re not in 4WD)

How to use a tractor differential lock?

What is the Differential Lock in a Tractor and How to Use it?

To engage the differential lock, simply step down on the differential lock pedal with your right heel. If the tractor is not moving and the differential gears are not turning, the pedal will not fully suppress.

First, a diff lock should not be used for on-road driving unless additional traction is needed due to weather conditions such as snow or ice. When driving off-road or on rough terrains such as dirt, gravel, mud, or snow, use your locking differential. You’ll only need to use your locking differential when you need more traction, so it’ll only be used for a few moments.

Differential Lock connects the wheel axles to provide the best traction possible on slick roads. A differential-lock can be activated by selecting one of two operating positions: Auto Lock—Press the Auto-Lock switch (A) on the armrest to enter the Auto mode.

Automatic and manual locking differentials are the two types of locking differentials.

1. Automatic Differential

When traction is lost, the automatic diff locks will engage. Once traction is restored, the diff lock will be released. When one wheel must turn faster than the others, some automatic locking diffs will disengage. The disadvantage though of Automatic locking differentials is often blamed for increased tire wear because they do not run as smoothly as normal differentials.

When locking and unlocking as the vehicle negotiates turns, some older automatic locking differentials are known to make a clicking or banging noise. Furthermore, automatic locking differentials can result in a loss of control on ice, while an open differential will allow one wheel to spin while the other remains stationary, without transferring power.

2. Manual Differential

Drivers with manual diff locks have more control over when and if extra traction is necessary. Manual diff locks come in a variety of styles, the majority of which is regulated by a switch on the dashboard or a gear stick. These can be powered by compressed air, an electromagnet, or a wire. The disadvantage though of this type is it’s more complicated because more pieces can malfunction. 

Some lockers enable the vehicle to come to a complete stop to engage. Human interaction is needed, as well as foresight into future terrain. When untrained drivers leave the differential locked on terrain that does not need a locker, they put a lot of stress on the driveline components.

When would you use a differential lock on a tractor?

The differential lock does just as it says, locking the driving wheels together to allow you to go further. You are not required to drive in a completely straight line, but sharp turns are not recommended

In a tractor or a vehicle, the differential allows the driving wheels to have different speeds. When spinning, this is important because the outer wheel moves faster than the inner. They would literally “burn rubber” if they were chained together and forced to travel at the same pace. However, if you’re driving on slick ground, one of your wheels can begin to spin, leaving you with no driving power.

Regardless of traction, the diff lock allows both wheels to turn at the same speed. This is advantageous if you reach rough terrain and one or more wheels leave the field, as maximum power is transferred to the remaining wheels, ensuring that you continue to drive in the desired direction.

If the tractor does not have a differential lock, you can use the left or right brake pedals to stop the spinning wheel, but these pedals must be disconnected from each other. When steering in a curve, the outside drive wheel has more room to turn than the inside drive wheel, so when one wheel has less momentum than the other, it will slip or spin uselessly, causing the tractor to stop. Activating the differential lock locks both wheels together, forcing them to turn, potentially allowing the tractor to continue going.

How fast can you drive with a differential lock on?

It’s never a good idea to race when the differential lock is on.

Running with the inter-axle lock engaged will not affect anything but fuel economy, according to Kevin Rutherford. So, no matter what, the inter-axle lock will lock the axles together for 50 percent power to each axle. Differentials would only lock in the axle’s tires so that they each receive 50% of the power sent to it.

I believe the best is 10-15 mph, but I know some people who go much faster. Off-road, however, they are quicker, the rear tires are already sliding in the dirt, dust, and sand, so it isn’t too difficult.