Have you ever noticed how some dump trucks have strange extra wheels connected to them that seem to be there aimlessly?
Even when installed on the top of the truck, those aren’t backups and aren’t for adornment.
Then, why are they there? You must be wondering why dump trucks have extra wheels. We’ll tell you all about it in this article.
Why Do Dump Trucks Have Extra Wheels?
The weight of a dump truck loaded with gravel can easily exceed the per-axle restriction. So, the additional wheels/axles are lowered to make the truck legal.
They are increased at other times to improve gas mileage and tire wear. This is the reason why dump trucks have extra wheels.
Let’s talk in detail about it. The axle directly behind the dump truck is known as the pusher axle. On the other hand, the axle in the back is known as the tag axle.
Trucks are legally authorized to carry only a certain amount of weight on each axle. The dump truck can legally carry a larger weight with a dead axle.
Each state’s department for transport determines the maximum weight a truck can carry per axle.
Because the weight of a dump truck loaded with gravel might easily exceed the per-axle restriction, the extra wheels/axles are reduced to make the truck eligible.
Although certain commonalities exist, these laws differ from one state to the next.
A single axle, for example, cannot carry more than 20,000 pounds. Also, the tandem axle has a limit of roughly 34,000 pounds.
On the other hand, they are also increased to improve gas mileage and tire wear.
The axle is lowered to enhance the weight capacity or to spread the cargo’s weight over more wheels.
This happens when crossing a bridge with a weight limit. When the axle is not used, it is elevated off the ground to reduce tire and axle wear and boost grip on the other wheels.
In particularly tight bends, lifting one axle also eliminates lateral scouring of the additional axle, allowing the vehicle to rotate more easily.
A dead axle, or lazy axle, is a free-rotating axle that is not part of the powertrain. For example, the rear axle of a front-wheel-drive car can be considered a dead axle.
