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What Are Full Lockers On A Semi Truck? (Solved!)

Have you wondered how semi trucks are able to control their traction when they drive in slippery conditions?

Many semi trucks make use of full lockers. If you want to find out more about full lockers, read on to find out…

Here’s a quick answer to What are Full Lockers on a Semi Truck:

Full lockers are used to lock the axles of a semi truck together. A full locker will lock the right-hand side wheel to the left side wheel. This will ensure that they rotate at the same speed to provide better traction in adverse weather conditions.

What does it Mean when a Semi Truck Has Lockers?

If a semi truck has full lockers, it means that it is capable of locking its axles. This will prevent the wheels from spinning and losing traction.

The right-hand side wheels will lock in the same position as the left-hand side wheels. This allows them both to spin at the same speed.

There are several uses for full lockers on a semi truck, and they are an essential feature to have handy.

Full lockers will help the semi truck gain more traction and prevent the wheels from slipping on the surface of the road.

What are 4 Way Lockers?

4-way lockers are the most common forms of full lockers found on semi trucks. The other form is 3-way lockers.

There is an essential difference between the two and how they can help your semi truck.

3-way lockers will only lock the rear axle, whereas 4-way lockers will lock both the front and the rear axles together.

This is helpful to get as much traction and power down on the road as possible when you need it most.

How do Full Lockers on a Semi Truck Work?

Full lockers are operated by the drivers from the cabin of the semi truck. They can be engaged and disengaged at the push of a button. In some cases, they might be activated by flipping a switch.

Once the full lockers are engaged, the semi truck will lock its axles. This means the right-hand side wheels will be locked to the left-hand side wheels.

In other words, the right side wheel will turn at the same speed as the left-hand side wheel. This will prevent the wheels from rotating at different speeds.

It helps gain more traction and prevent the tires from slipping.

How Fast can you Drive your Semi Truck with Full Lockers Engaged?

Locking your axles will not prevent you from driving faster. However, it is highly recommended not to go over 25 miles per hour with the full lockers engaged.

Firstly, there is no need to drive with the full lockers engaged when running at speed, they are only needed at lower speeds.

Driving with the full lockers on will increase fuel usage. This is because the engine is working harder to spin the axles while they are locked. When the axles are not locked, the power can easily be split between different wheels.

Another reason not to use the full lockers while driving at higher speeds is that it will severely impact the semi truck’s ability to go around corners.

When a vehicle goes around a corner, the outside wheels need to turn faster than the inside wheels because they need to cover more ground in the same amount of time. This is called the Ackermann theory.

When the axles are locked, both wheels on the left and right-hand side are forced to move at the same speed, and therefore your semi truck will struggle to turn.

This will also have a massive impact on your tire wear. When the axles are not locked, they are free to rotate as they are needed.

However, if they are fixed, they might be wearing excessively because they always need to rotate at the same speed as the others.

How do you Switch on the Full Lockers on a Semi Truck?

The full lockers on a semi truck are controlled from within the cabin by the driver. They can be engaged and disengaged by a button or a switch.

In most cases, it will be accompanied by a ‘lock’ and ‘unlock’ symbol, or one similar to the 4×4 symbol in a pick-up truck.

If a semi truck has a 3-way full locker, it will have one switch in most cases to lock the rear axle.

If a semi truck has a 4-way full locker, it will have two different switches to control the front and the rear axles separately.

When should you Use Full Lockers on a Semi Truck?

Full lockers are helpful when it comes to semi trucks, and drivers need to use them in several different scenarios.

The first scenario is adverse weather. Full lockers will be needed to prevent the wheels from slipping and losing traction in heavy rain or snow.

Having the full lockers on will allow the semi truck to pull away from a stop cleanly and smoothly rather than spinning the tires and sliding around.

Full lockers are also helpful when it comes to sand and mud. Being able to lock the axles together and get them spinning at the same speed will help you in these slippery conditions.

Often, semi-lockers are also needed when going uphill and downhill. Due to the extreme weight that semi trucks usually carry, they can experience a loss of traction when driving on steep gradients.

Locking the wheels will help the semi truck to ascend or descend much easier.

Are Full Lockers, Differentials, and Power Dividers the Same Thing?

Full lockers and differential locks have the same purpose. Both can lock the wheels on the same axle together.

However, these differ from a power divider. The power divider can lock two axles together to ensure that they are running at the same speed.

In other words, a power divider locks the front and rear axles together, while the differential locks the left and right sides of one axle together.

While the power divider might lock the front and rear axles together, it does not necessarily control the left and right sides of the axles.

Is it Necessary to Have Full Lockers on a Semi Truck?

It is not necessary to have full lockers on a semi truck. However, it can be extremely helpful when you are in a challenging situation.

Due to the large size and weight of semi trucks, they can cause many problems when they become stuck. For example, if they were to become stuck in the mud, they could end up blocking a lot of traffic.

It can also be difficult to tow them out of these situations, especially if they cannot lock their axles and put their power down to help the tow truck.

There is also somewhat of a safety risk involved using a semi truck without full lockers in adverse weather.

If there is heavy rain or snow, the semi truck could quickly lose traction and cause an accident that might cost you even more money.

How do you Tell if a Semi Truck has Full Lockers?

The easiest way to tell if a semi truck has full lockers is to check the cabin and look for the switch. However, in some cases, the full lockers might not be working.

The best way to check if they are working is to jack the semi truck up and turn the full lockers on. Try to turn the right-hand side wheels.

If you can easily spin the right-hand side wheels, then the full lockers are not working correctly. If the right-hand side wheel does not turn at all, then the full lockers are working.

This is because the full lockers will lock the right-hand side wheel to the left-hand side, and it will only turn if the left-hand side wheel is turning.

Can you Put Lockers on a 2WD?

You can only put 3-way lockers on a two-wheel-drive semi truck, however, they will not be as effective.

This is because the 3-way lockers can only lock one axle, which is the driven axle. In other words, the axle where the engine power is sent to.

Can you Put Lockers on a 4WD?

Full lockers work best on a four-wheel drive semi truck. The four-wheel drive system will allow you to lock both axles if needed and provide much better traction.

3-way lockers can also be used on a four-wheel drive vehicle, but they are much less effective that 4-way lockers.

How do you Maintain Full Lockers on a Semi Truck?

The full lockers are often neglected when maintenance is being done on a semi truck. However, if they are not maintained, they could cause you severe headaches.

Without proper maintenance, the full lockers could fail altogether. This could result in them not engaging correctly or locking the axles entirely.

The element that needs to be checked on the full lockers is the gears, which locks the wheels together. These can take the strain and become damaged over time.

The full lockers also need a fluid change. This can be done anywhere between 50,000 and 100,000 miles.

How to Know if the Full Lockers on Your Semi Truck Works?

It can be difficult to tell if the full lockers on your semi truck are working while you are driving. There simply is no way to tell.

The best way to check that they are working is to lift the semi truck. It is best to lift all four wheels off the ground, however, you could also jack the semi truck up to have one axle off the ground.

You need to make sure that the full lockers are engaged, and then try to turn the right-hand side wheel that is off the ground.

If it is locked in place, then the full lockers are working properly. However, if the wheel is still turning comfortably, the full lockers are not working, and you should get them checked out.

Is it Expensive to Fix the Full Lockers on a Semi Truck?

The cost of a new full locker on a semi truck can go up to $1000 per unit. The labor costs can also become expensive since it is a more complex job than usual.

However, if the gears need replacing or a fluid change is required, the cost will be significantly less.

It is essential to prevent as much damage from being done to the full lockers as possible.

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