1,600 Pounds Over on the Drives with Six Loose Pallets
A shipper has loaded 43,000 lb of canned goods into your 53-foot van: 20 pallets double-stacked in the nose, and 6 single pallets standing about 5 feet from the rear doors, not touching each other and not tied off. You scale the rig, a 3-axle tractor with sliding tandem and a trailer with sliding tandem, and get: steering axle 11,850 lb, drive tandems 35,600 lb, trailer tandems 29,550 lb, gross 77,000 lb. Your limits are 12,000 lb on the steering axle, 34,000 lb on each tandem, and 80,000 lb gross. The trailer tandems are pinned at the 43rd hole of 55, counting from the front. The six loose pallets weigh 2,400 lb each. It is 20 minutes to your appointment and the scale is 2 miles from the dock.
1. Which axle group is illegal, which direction do you slide the trailer tandems, and why is that the right direction?
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Add it up first: 11,850 plus 35,600 plus 29,550 equals 77,000 lb, so gross weight is legal. The drive tandems are the problem at 35,600 against a 34,000 limit, 1,600 lb over. The steering axle at 11,850 is legal but only 150 lb under its limit, and the trailer tandems at 29,550 have 4,450 lb of room.
Slide the trailer tandems forward, toward the kingpin. That shortens the lever between the trailer axle and the kingpin, so the trailer axles take a larger share of the trailer's weight and the tractor takes less. It pulls weight off the drives and off the steering axle at the same time and puts it on the trailer tandems, which are the only group with room.
Do not guess the amount. Move forward in steps, since a hole commonly moves a few hundred pounds depending on load and spacing, and re-weigh all three axle groups after each adjustment. Watch two limits as you go: trailer tandems must stay at or under 34,000 lb, and the steering axle must not fall so light that steering and brake balance suffer.
If you run out of holes, the load itself, not the axles, has to move rearward.
2. What does the law and good practice require for the six loose pallets, and what would you actually install?
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Six pallets at 2,400 lb each is 14,400 lb of unsecured cargo, and the fact that they are not touching anything is the problem: nothing blocks them from sliding forward under braking, sideways in a turn, or rearward under acceleration. Cargo must be secured against tipping and against horizontal movement, and friction between pallets alone is not securement.
The rule of thumb is that the tiedowns securing the cargo must have an aggregate working load limit of at least half the cargo weight: 0.5 x 14,400 equals 7,200 lb. That is a floor, not a target, and it assumes a good friction surface and reasonable strap angles.
Practical fix for palletized goods in a van:
- Block forward movement with a rated load bar or bulkhead against the pallets.
- Add load bars or straps at the rear so nothing can shift back into the doors; a shifting pallet can burst them open in a hard stop.
- Use load-lock bars or straps at each row, and strap over the whole row rather than individual pallets.
- Keep cargo out of contact with the doors.
- Re-check straps after the first 25 to 50 miles, since pallets settle.
3. After the fix, what else about weight distribution and load placement should you think about on this load, including what the scale ticket cannot tell you?
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With 20 pallets double-stacked in the nose and only six singles at the rear, the load's center of gravity is far forward. That is why the drives carry 35,600 lb and the trailer tandems only 29,550. Forward-biased loads feel stable in a straight line, but they load the drive tandem, shorten tire life, and on a shorter-wheelbase tractor can push a steering axle past 12,000 lb.
Once you slide the tandems and re-weigh, look at the whole picture, not just the violated axle. A legal gross weight with one axle over its limit is still an overweight violation, and a steering axle that is too light reduces steering grip and lengthens stopping distance. Brake balance also changes: the axle group carrying more weight does more of the stopping.
What the scale ticket cannot tell you is whether the load will stay where it was weighed. If those rear pallets slide backward under braking, weight shifts off the drives and onto the trailer tandems, and a couple of thousand pounds moving the wrong way is enough to undo your scale ticket and change how the rig handles in a panic stop.