Why do trucks lift their rear wheels?

Meet Alice: this is a sloth.

Sometimes even something as mundane as a truck can baffle your brain. Especially if it’s a truck with raised rear wheels. What, one wonders, did they climb? Is this a way to transport spare wheels or evidence of a technical malfunction of the car?

Certainly not both. And in general, this is not just some kind of “raised wheel“! It is a whole mechanism that even has its own name – sloth. In a nutshell, it is needed in order to increase the permitted carrying capacity of the vehicle. After all, the more axles a truck has, the more increased obligations in tons it will take on.

Sloths put not only on trucks, but also on trailers

For example, in Russia, each axle of a truck should not have more than 7–7.5 tons of load. Thus, a two–axle truck cannot carry more than 15 tons, but a three–axle truck is allowed to carry over 20 tons. Do you dare? This is where the sloth comes in handy, turning a two–axle car into a three–axle one.

True, three axles are needed for a truck only when fully loaded, while empty it is more convenient and economical for it to ride on four wheels. So the handling is better and the fuel consumption is lower. Depending on the design, the driver can control the sloth by lowering or raising the roll axle with a button, or the sloth is triggered by itself, reacting to the level of weight load.