A dump truck works by using hydraulic pistons that lift the dump box at a steep angle, allowing whatever is in the dump box to fall into whatever pile the dump truck designates. Another type of dump truck uses a panel held in place by hydraulic cylinders in the dump box. The cylinders push the panel to the back of the dump box, forcing the contents of the box through a tailgate.
The main body of many dump trucks is similar to a flatbed truck and has one axle under the cab and up to three axles under the dump box. The dump box usually has a tailgate with a top hinge that opens on its own when dumping contents. Many trucks use hydraulics over pneumatics, while their internal combustion engines are either gasoline or diesel powered. The engine powers the dumping mechanism, while a power take-off tethered to the transmission powers the hydraulics.
In order for the dumping mechanism to work, the truck must be running. There are several safety measures implemented in the operation of the truck, including the requirement that the transmission is in neutral before the power take-off engages. A lift dumping mechanism is the most popular mechanism for dump trucks. However, many construction companies prefer the panel dumping mechanism because it does not require vertical clearance before dumping.