Weight Distribution, Axle Limits, and Load Securement
Weight Distribution, Axle Limits, and Load Securement
This domain tests axle limits, bridge formula basics, and load placement. With multiple trailers, weight on the dolly and rear trailer matters as much as weight on the tractor.
Limits
- Federal gross vehicle weight limit: 80,000 lb.
- Single axle: 20,000 lb; tandem axle: 34,000 lb.
- The bridge formula limits weight over a group of axles based on spacing.
- State and posted limits may be lower; check signs.
Distribution
- Place heavy freight over the trailer axles, not at the rear.
- Do not overload the converter dolly; it has its own rating.
- Balance the load so no axle is over its limit.
- Check axle weights at a scale.
Securement
- Use tiedowns with an aggregate working load limit at least half the cargo weight.
- Secure cargo so it cannot shift forward, back, or sideways.
Worked example
A load puts 36,000 lb on a tandem axle. That exceeds the 34,000 lb limit. Shift freight forward or reduce the load before moving. A heavy rear trailer also adds weight to the dolly and lead trailer.
Traps
Ignoring the dolly's weight rating, loading all freight at the rear, and assuming the gross weight is the only limit.