How do you test a fifth wheel?

In today’s blog post, we will answer the following question: How do you test a fifth wheel? We will explain why it is important to do a pull test on a fifth wheel. We also tell you how to properly hitch a fifth wheel. 

How do you test a fifth wheel?

Testing a fifth wheel trailer, also known as a tug test or pull test, is essential to make sure that the trailer is properly and safely connected to your towing vehicle. Doing a pull test is quick, easy and necessary in order to ensure both your safety and that of other drivers!

Here’s how you can test a fifth wheel trailer:

  1. We start off by putting a wheel chock on the backside of the front tire or you could do it on the backside of the rear tire, it doesn’t matter.
  1. Next, back the truck up so that it is aligned with the pin box of the trailer. Depending on the landing gear that you have on your fifth-wheel, lower the trailer so that the pin box just touches the fifth wheel plate. This will cause the RV to raise slightly as the fifth wheel plate slides under the pin box. 
  1. Next, put the truck in reverse and slowly back up until the pin box engages with the fifth wheel hitch and the jaws lock. You could also lower the pin box just enough so that it engages with the fifth wheel plate that you raised. This is necessary to remove the stress on the landing gear.
  1. Continue retracting the landing gear until you have about a one half inch gap between the bottom of the foot of the landing gear and the wood block(wheel chock). This allows the fifth-wheel to settle on the blocks gracefully.  
  1. Keep in mind that if the hitch lets go when you do the pull test this prevents the RV from landing on the bed of your trailer and crushing it.  Finally, relocate the wheel chock to the front of the tire and then do the pull test.
  1. You may have to move the vehicle forward, just slightly, to take the pressure off the wheel chock. This is okay as long as you only move forward just an inch or so. As long as the landing gear has room to land back on the blocks that’s fine!
  1.  Now you’re ready to do the pull test. Simply put the truck into forwarding gear, give it a little gas and if the fifth wheel is properly secured to the hitch then the truck will not move. 
  1. Finally put the truck in reverse and back up far enough so that you can retrieve all the blocks.Then you’re good to go!

If this is the first time of towing a fifth wheel trailer or you just failed a pull test, keep reading to understand how to properly hitch a fifth wheel trailer to your towing vehicle, and how to adjust the hitch height. 

How to correctly hitch a fifth wheel trailer

While the mechanical connection is very different from a conventional trailer bumper setup, the wiring is exactly the same. A round seven-bolt plug terminates a seven-conductor harness on the trailer, which is in turn mounted to a corresponding socket on the towing vehicle. Therefore, wiring a fifth wheel trailer hitch is a relatively straightforward project. 

Things you will need:

  • Cable Plug
  • Zip ties
  • Knife
  • Wire Stripper Screwdriver
  1. Purchase a seven-conductor length of trailer cable; it should be as long as the fifth-wheel trailer, plus 12 feet. Trailer cable is readily available at auto parts stores, recreational vehicle dealers, and companies that install trailer packages.
  1. Level the fifth wheel trailer towing, flat place where all-around access is protected from traffic. Block the wheels.
  2. Lay the cable on the ground next to the fifth wheel trailer. Use zip ties to secure the front near the mechanical fifth wheel connection, leaving approximately three feet of cable hanging loose.

Use a utility knife to cut about 2 inches from the outer end sheath, being careful not to damage the insulation of the seven inner wires. Use wire strippers to remove about a half inch of insulation from each of the seven inner wires.

  1. Use a screwdriver to loosen the clasp holding the case in place from a round seven-pin plug, then remove the case from the internal terminal hub and slide it – small hole first – through the wire. 

Connect the wires to the terminals in the following combinations: white to terminal one, blue to terminal two, brown to terminal three, black to terminal four, yellow to terminal five, green to terminal six, and purple for terminal seven – in the center. Reset the case and bra.

  1. Route the cable back underneath the fifth wheel trailer, following the frame rails and chassis, with a zip tie approximately every 10 inches to secure where it will not be susceptible to damage or create a tripping hazard. It matters little which side of the trailer the cable runs underneath.
  1. Use the knife to separate the outer casing on the shaft, and separate the white and blue wires. Attach the white wire to the chassis and connect a branch of the white wire to the output side of the electric brake circuit, these circuits are accessed at the rear of the wheel hubs at the 12 o’clock position. Connect the blue wire to the upstream side of the electric brake circuit.
  1. Continue to route the cable back to the rear of the fifth wheel trailer and connect the remaining cables from the rear light clusters. The colour-coded wires are connected in a conventional way as follows: green wire to the right turn (passenger side) of the circuit, the yellow wire to the left turn (driver’s side) of the circuit, brown wire to the circuit of taillights and white wire to ground circuit. 

The purple wire is intended to serve an auxiliary function, such as turning on the reversing lights.

How do you adjust the height of a fifth wheel hitch?

It is possible to adjust the height of a fifth wheel hitch in just a few simple steps.  The hitch system between a towing vehicle and a trailer needs to be configured correctly so that the two can work together safely. The towing vehicle must be capable of supporting the weight of the trailer. 

Adjusting the hitch height on the towing vehicle and trailer will help you create a strong connection in the trailer hitch coupler, which will help reduce the risk of the trailer separating from the towing vehicle.

Here’s how to adjust the height of a fifth-wheel hitch step by step:

  1. Use a rag, cleaning brush, and wire thinner to clean the bolt holes and other areas where the hitch ball will sit. The wire brush will make removing cocky road debris a simpler task because it will tear the dirt up.
  1. Use the tape measure to determine the distance between the towing vehicle and the ground. Also measure the distance between the trailer and the ground.
  1. Adjust the height of the trailer hitch by changing the tension of the trailer spring bars. The trailer and the towing vehicle must be fixed at the same height. The spring bars can be located along the frame A of the trailer.
  1. Loosen the nut and lockwasher under the hitch ball. Raise or lower the hitch ball so that the trailer hitch can be sitting on top of the ball. Retighten the lock washer and bolt after the balloon has been adjusted to the required height.
  1. Place the trailer hitch on top of the hitch ball and lower the trailer onto the hitch ball so that the hitch coupler engages.

The bottom line

Pull testing a fifth wheel is easy to do and there isn’t really a reason why you shouldn’t take a few minutes to do this every time you hook your trailer to your towing vehicle. It is needless to say what would happen if you didn’t secure the fifth-wheel properly!

Please feel free to get in contact if you have any questions or comments on the content. 

FAQ on How do you test a fifth wheel?

How does the fifth wheel hitch work?

A fifth wheel hitch l works by locking a kingpin in the lockjaw. The kingpin is similar to a hitch coupler and is attached to the semi-trailer, while the locking jaw acts as the receiver for the hitch

How do I reduce the weight on my 5th wheel hitch?

To reduce the weight on your 5th wheel hitch, simply move all your luggage in the back of the trailer. If you want to increase the weight on your 5th wheel hitch, just do the contrary – move the things to the front of the trailer. 

Can a fifth wheel hitch be removed?

Yes, a fifth wheel hitch can be removed.  A fifth wheel, or gooseneck, hitch sits in the middle of the sturdy truck bed, where it can support more weight in that area. This also makes it easier to turn around tight corners. 

What is a fifth wheel hitch?

A fifth wheel hitch is specially designed for the beds of vans and flatbed trucks. With a towing capacity between 5500 and 9000 Kg and a weight capacity between 550 and 770 Kg, 5th wheel hitches are installed just above and above the rear axle of a truck. 

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