Newbies - Tips From the Trainer
Sliding Rear Axles
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|Q||How do you know when to slide the rear axles of your trailer to allow for weight distribution?|
There are a couple of reasons to have to slide the rear axles on the trailer. The obvious and most common reason to slide the trailer tandems is to distribute weight either forward to share more weight with the drive axles or to move weight to the rear to take weight off of the drive axles. The only way to tell where to slide the axles or to determine if you even need to is to weigh the whole truck on a scale. These scales are located at most truck stops with accompanying fees. There are hardly any shippers that have scales to weigh the trucks on their property.
The standard federal legal weight on the interstate is 80,000 pounds gross. That’s everything, truck, freight driver etc. The weight must be spread out on the axles to make things safe and legal. The standard weights are 12,000 pounds on the steering axle, 34,000 pounds on the drive axles and generic tractor-trailer 34,000 pounds on the trailer tandems. There are all sorts of different set ups and weights allowed by different states and different issues if you add more axles. We will just stick to the generic truck you see running down the freeways all over the country.
Another tiny little secret that the schools do not tell you and that mosSo you load a tractor-trailer at a shipper and go to the scale and weigh. If you scale the truck and the axles are at or under the weights above, then you are pretty much legal to go anywhere in the country. There is only one problem with this, which brings us to the other reason that you may have to slide the tandems on the trailer: bridge laws. There are certain states that require the axles on a tractor-trailer be spaced at certain measurements to be legal. So the problem with the weight rules is that you while you can be legal at the right weights, you can still get in trouble for having your axles too far apart or having a wheelbase that is too long.
You can find all of these requirements in most trucker atlases and of course most companies will give you a handout with these requirements. They also have most of their trailers marked with a label to tell you where to place the axles for the different requirements in different states. The basic rule is that you set the axles for the most restrictive state on your route before you load the trailer. This way, if the rear is too heavy, the shipper must reload properly because there is no way that you can slide the axles to the rear and further if it would make your wheelbase too long to be legal. Most shippers do a good job at loading the trailers and there are not too many loads that cannot be scaled legally with a little tweaking here and there. There are some loads though that you cannot be bashful about and telling the shipper and/or your company that you will not pull down the road.
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