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Trucker's Journal

I've been a trucker since November, 2004. Before that I was an accountant for many years. I'm having fun and actually making more than I did before. Go figure....

Location: Midwest, United States

Saturday, April 14, 2007

Moving tandem axles

In response to a request, here's the lowdown on weight distribution on the trailer. Each type of axle/tire combination is allowed a certain weight limit and the overall limit for the truck/trailer combination is also regulated by law. For most trucks with single steer axles and twin drive axles together with a trailer with tandem axles, the limit overall is 80,000 pounds. The steers are allowed 12,000, and both the dual axle sets are allowed 34,000. You may very well be at or under your allowed gross weight but have one or more axles overweight. I'm sure you have driven by the weigh stations on the interstate and seen the parking lot behind the building occupied by a truck or three and wondered why they are there. From the scuttlebutt I've heard, the most common reason is a log violation and the second most common is weight violations. Most truckers are aware of their "tare" or empty weight with a truck/trailer combination (mine is about 32,500 pounds most of the time) and can add their freight weight to that to see if it's legal. However, many don't bother to get their axle weights to see if they are axle legal also.

Here's where the moving of the axles comes in. If you are legal overall but your rear axles are overweight, you need to redistribute it toward the front. How can that be done? Well, remember when you were young and played on a see-saw which could be moved in the middle? If you and your friend stayed there on either end but moved the middle, you would have to work harder on one end to push and vice versa on the opposite end. So it is with the axles. If you are over on the rear, you need to reduce the rear weight by moving the axles back, placing more of the total trailer weight on the front of it. You do that by setting the trailer brakes and pulling the pin which locks the axles in place. You then move the truck and trailer forward while the axles sit still. The holes are generally placed so that each one changes the weight by about 400#, so if you're 1,000 over on the rear, you would move forward about 3 holes. If you're over on the drive (dual truck) axles, you do the opposite by backing up.

After you move them and relock the pin, you need to reweigh to see if you are indeed legal now. At many truck stops, the scales give you axle weights with separate platforms, but on a single platform scale, you need to get a total weight, then progressively pull off the scale with one axle or set of axles at a time to get weights and then do the math to see if you have done what you need to do.

Many states allow up to 1,000 over on any axle or set but some don't, so you're best to get it right. If you can't move it enough, then you have to get reloaded with the freight moved around inside the trailer and start the weigh/move process all over again.

On older trailers, you sometimes can't unlock the pin and move them, so many truckers try to avoid scales. The problem with that is that if you are caught doing it, your fine will be higher!

Another thing to remember is that some states regulate the length of the wheelbase of the trailer--in Michigan where I'm based, the distance from the kingpin (on the trailer where it mates with the fifth wheel on the truck, usually 3 feet from the front of the trailer) to the center of the axles at the rear can be no more than 40' 6". There's a lot to "juggle" to get your weight and length right.


Blogger Garbage Goddess said...

I have been trying to figure out how to explain differences in weighing when we ship out recycling and knew there was a relation to where the weight was on a truck to the axle and location. Your post is one the clearest, simplest explanations I have found. THANK YOU!

5:39 PM  
Blogger Unknown said...

So useful information about the truck. Thanks for sharing this.

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1:29 AM  
Blogger Amelia said...

Thanks for the nice information.This will help a lot of users.You can place trailer orders online on the website of Tramp Trailers by selecting the features that you want whether it is the type of trailer, axle number, axle weight, size and colour of trailer, you can choose them all.Find more about at here Tandem Trailer

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