Space Needed Between Upper & Lower Fifth Wheel

‍If you’re an RV owner, whether campers, motorhomes, or trailers, it’s important to know how much space is between the upper and lower fifth wheel.

There should be no space between the upper and lower fifth wheel. Inspect all couplings before going on a trip to ensure they're secure and in good condition. If there's space between the upper and lower fifth wheel, you must address the issue before hitting the road.

I understand that safety is a top priority for most drivers, and that's why I've provided you with accurate information on 5th-wheel coupling. With my extensive experience in the RV and trucking industry, I’m committed to providing you with reliable and trustworthy information you can count on. So, read on to learn all about the world of upper and lower fifth wheels!

‍How Much Space Should Be Between the Upper and Lower Fifth Wheel?

So, how much space should be between the upper and lower fifth wheel? When coupling your RV trailer to a truck, it’s important to ensure that there’s no space between the fifth wheels.

In some cases, the maximum space you can have between the fifth wheels is about 1 inch, depending on your jurisdiction’s laws.

This is because any space between the two could indicate that the king pin may be on top of the closed fifth-wheel jaws, which can cause the trailer to come loose easily.

That said, different states have their own regulations. Based on Truck News, here are some examples of the allowed space:

The Proper Positioning of the Fifth Wheel When Coupling

You need to properly position the fifth wheel when coupling to ensure that you don’t have space between the upper and lower fifth wheel. Here are the steps you need to follow:

1. Back your truck up slowly until the kingpin (usually a two to three-and-a-half-inch steel pin) is directly over the center of the 5th wheel.
2. Lower the landing gear until the weight of the trailer is resting on it. Ensure to park your trailer brakes before lowering the landing gear.
3. Once the trailer’s weight rests on the landing gear, release the fifth wheel locking mechanism to open the fifth wheel jaws.
4. Back up slowly until the kingpin is resting on the fifth wheel.
5. Raise the landing gear until it’s clear of the pavement.
6. Double-check that the kingpin is properly seated in the jaws of the fifth wheel.
7. Lock the fifth wheel mechanism.

By following these steps, you can ensure that there’s no space between the upper and lower 5th wheel, which will help prevent any accidents or incidents while on the road.

Acceptable Way of Checking if the Fifth Wheel is Securely Attached

When coupling the tractor to the trailer, it’s crucial to ensure that the fifth wheel is securely attached. One way to do this is by checking how much space is between the upper and lower fifth wheel.

The following steps will help you check if your fifth wheel is securely attached:

1. First, ensure that your tractor is properly aligned with the trailer. You can do this by using the mirrors or by having someone guide you.
2. Next, slowly back up your tractor towards the trailer until you hear the locking mechanism engage. This will indicate that the fifth wheel is securely attached.
3. Stop your tractor and exit the cab once you hear the locking mechanism engage. Then, go to the back of the tractor and look at the amount of space between the upper and lower fifth wheel.
4. The acceptable amount of space between the upper and lower fifth wheel is approximately 1/4 -1 inch. If the space is too small or too large, like two inches to about five inches, you may need to adjust the position of the tractor or trailer.
5. If the space is within the acceptable range, you can connect the air and electrical lines and perform a tug test to ensure the connection is secure.

Remember that it’s essential to check the fifth wheel connection every time you couple the tractor to the trailer. By following these steps, you can ensure that your fifth wheel is securely attached.

Importance of Proper Space

Truck drivers must ensure proper space between the upper and lower fifth wheel. This space is the gap between the two parts of the fifth wheel that can cause a serious injury if not properly maintained. Here are some reasons why maintaining proper space is important:

Proper Coupling

When the space between the upper and lower fifth wheel is not correct, it can cause improper coupling. This can disconnect the trailer from the tractor while in motion, causing a dangerous situation.

Ensuring that there’s no space between the upper and lower fifth wheel will help ensure proper coupling, making your ride safer.

Trailer Maintenance

Proper space between the upper and lower fifth wheel is also important for the maintenance of your trailer. When there’s too much space between the two parts of the fifth wheel, it can cause damage to the trailer's kingpin.

This can lead to costly repairs and downtime. Maintaining proper space can avoid these issues and keep your trailer in good condition.

Inspections

During pre-trip inspections, the following tests should include checking the space between the upper and lower 5th wheels. If there’s too much space, it can indicate that there is an issue with the coupling or the trailer itself.

By catching these issues early, you can avoid potential problems while on the road. For example, you can avoid an out-of-service violation (OOS), which can impact your CDL and your ability to drive commercially.

Always inspect the coupling, check the kingpin, and make sure that the brakes and valves are properly connected before you hit the road.

Testing

Proper space between the upper and lower fifth wheel is also important during testing. When testing your tractor and trailer, you want to inspect everything to ensure that everything is working properly.

Too much space between the upper and lower fifth wheel can cause issues during testing, which could lead to failure of the following tests and delays in getting back on the road.

Safety Concerns

Maximum safety should always be your top priority when it comes to coupling a tractor and trailer. There are several safety concerns to remember during this process, including:

Closed Fifth Wheel Jaws

One of the most important safety concerns to keep in mind is ensuring that the 5th wheel jaws have properly closed around the kingpin’s shank.

If there’s space between the upper and lower fifth wheel, this could be an indication that the jaws have not closed properly. This could result in a loose coupling, which could be extremely dangerous while driving.

Air Lines and Ground

Another important safety consideration is ensuring that the airlines and ground are properly connected. This includes checking the service line, emergency line, and protection valve. You should also check the air tank pressure and make sure that the glad hands are secure.

Coupled Unit

Once the tractor and trailer are coupled, it's important to ensure the coupled unit is secure. This includes checking the fifth wheel locking lever, ensuring the front trailer supports are up, and the trailer rests on the tractor. You should also check the trailer tanks and trailer wheels to ensure they’re in proper condition.

Free Practice Tests

As part of your pre-trip inspection, you should always inspect the coupling. This involves checking for any space between the upper and lower fifth wheel.

You can also take advantage of free practice tests to ensure you understand all CDL topics related to coupling and other safety concerns.