The short version is: move the trailer tandems toward the axle group that is too heavy. If the drives are heavy and the trailer tandems have room, slide the tandems forward, toward the tractor. If the trailer tandems are heavy and the drives have room, slide them back, toward the trailer doors.
A practical scale-house process
- Read the steer, drive, trailer, and gross weights from the same ticket.
- Identify the group that needs weight removed and confirm the other tandem group can receive it.
- Check how much rail is available in the needed direction.
- Make a conservative whole-hole move and confirm all locking pins are seated.
- Reweigh. Use the actual change instead of assuming the first rule of thumb was exact.
When a trailer has no useful position numbers, count from the frontmost usable locking hole and write down the starting position. CDLMath treats that as position 1. Sliding forward lowers the position number; sliding back raises it. A consistent count matters more than matching somebody else's trailer markings.
A slide trades weight between the drive and trailer tandem groups. It does not reduce gross weight. It also normally does not fix a steer-axle problem. If both tandem groups are heavy, freight may need to be reworked or removed rather than shifted.