Overweight Axles at a Missouri Weigh Station
You are at a Missouri weigh station with a 3-axle tractor and a tandem-axle trailer. The scale reads: steer axle 12,500 lb (limit 12,000), drive tandems 34,500 lb (limit 34,000), trailer tandems 33,000 lb (limit 34,000). Gross weight is 80,000 lb (limit 80,000). The load is palletized and secure; you cannot shift or remove freight. The tractor has a sliding fifth wheel, and the trailer has sliding tandems. The scale operator tells you to fix the axle weights before you leave. You have a wrench and can slide the fifth wheel and trailer tandems. The next scale is 40 miles ahead. You want to make the smallest safe adjustment and verify it on the scale. The pavement is level and dry.
1. Identify which axles are over or under and propose a sequence of slide adjustments that could bring all axles legal without offloading.
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The steer axle is 500 lb over, the drive tandems are 500 lb over, and the trailer tandems are 1,000 lb under. Gross is exactly 80,000 lb, so the fix must redistribute weight. First, slide the fifth wheel rearward to transfer roughly 500 lb from the steer axle to the drive tandems. That should put the steer at about 12,000 lb and the drives at about 35,000 lb, with the trailer still at 33,000 lb. Second, slide the trailer tandems rearward to transfer roughly 1,000 lb from the drive tandems to the trailer tandems. That should bring the drives to about 34,000 lb and the trailer tandems to about 34,000 lb, with the steer staying near 12,000 lb. The exact slide distance depends on the tractor and trailer geometry, so move in small increments and reweigh after each adjustment. Do not guess a large slide and drive away.
2. Why is sliding the trailer tandems forward the wrong first move here?
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Sliding the trailer tandems forward transfers weight from the trailer tandems to the drive tandems and can also add load to the tractor. That is the opposite of what this combination needs. The drive tandems are already 500 lb over, and moving the trailer axles forward would make them heavier while reducing the underloaded trailer tandems. It might make the trailer scale reading look better, but it would worsen the legal violation on the drives and could add to the steer axle. The correct first move is to shift weight off the steer axle with a small rearward fifth-wheel slide, then shift weight off the drive tandems onto the trailer with a rearward trailer-tandem slide. Always reweigh because sliding too far can create a new overweight axle.
3. After one adjustment, the scale reads steer 12,100, drives 33,900, trailer 34,000. What now?
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The steer axle is still 100 lb over, the drive tandems have 100 lb of room, and the trailer tandems are at the limit. Make the smallest correction: slide the fifth wheel slightly rearward to transfer about 100 lb from the steer axle to the drive tandems. That should bring the steer to about 12,000 lb and the drives to about 34,000 lb while the trailer stays at 34,000 lb. Reweigh to confirm. Do not slide the trailer tandems further rearward, because the trailer is already at its limit. If the fifth wheel is already at the end of its travel or the adjustment cannot be made safely, do not leave overweight; contact dispatch to reposition the load or use a different tractor or trailer. The goal is a legal, verified scale ticket before the next 40 miles.