Sliding Tandems

For the newbies or not so newbies

Here is a tip on sliding tandems.

Sliding tandems is necessary and required to accomplish three things:

1. To move weight off of the tractor’’s axles rear to the trailer tandem axles.
2. To adjust weight off of the trailer axles and move some of the weight forward to the tractor axles.
3. To set the vehicles “bridge length” to a length that meets the bridge law (axle spacing) requirements of the state you are operating or will operate in.

The standard and allowable weight for a regular five-axle truck and semi-trailer on the Interstate system is as follows:  steer axles 12,000, drive axles 34,000 and the tailer tandems are 34,000. This takes the truck to the acceptable standard weight of 80,000 pounds. A few states out there require less on the axles.  Be aware of where you are going and roads you are traveling.  As a rule, you should be scaling out or weighing all your loaded trailers to keep you from receiving a ticket.  

The weights mentioned are in a perfect world and we all know that’s not happening.  Grossing out at 80,000 pounds is easier said than done.  If you scale the truck and you’re not overweight on the steer axles, and the weights are close to equal on the drive axles and the trailer tandems, you are good to go. Ideally, for safety it is better to have more weight on the drive axles than the trailer tandems.   Slide the axles to the rear to get some weight to move forward to the drive axles if you scale out and the drive axle weights are lighter than the trailer tandems.

Be sure to FIRST check the bridge length requirements to make sure you are not sliding the axles too far to the rear to meet the bridge law requirements! It is important to remember that you can have legal weights on all of your axles and still have a huge potential problem at the weigh stations. If you are legal on these axles and are found to be “over bridge,” you are going to have to get the load moved to allow more weight to be moved forward so you can slide the trailer tandems up to meet the bridge length requirements. In order to do this you’ll need to physically get inside the trailer and move the freight forward!  Now, if the trailer is fully loaded and you are over-bridge and overweight, some of the freight will need to be removed before being allowed to continue. This will likely result in a major violation from your company, plus a pretty hefty fine from the DOT.  Not to mention the lost time to get to your receiver.

Sometimes there is just no way around getting the tandems to weigh less than the drives.  You CAN still legally take the load to where it needs to be, but you must REALLY be more careful when changing lanes and any other side-to-side maneuvers. If these weights are excessively different, you may want to call your dispatch with the problem or refuse the load.  More weight on the drive axles is always preferable.

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