A dumper is a type of motorized vehicle that is typically used to move materials around a construction site. The configuration of a dumper usually involves the driver sitting at the back of the vehicle, while the materials container is on the front. This container may be powered by electric motors, hydraulics, or operated manually. Most dumpers are four wheeled, diesel powered vehicles, though some are fitted with rubber tracks to offer better traction. In addition to hauling and dumping materials, a dumper may also function as a tractor if a towing eye has been attached.
Traditional dump trucks typically have a closed cab that sits at the front of the vehicle and a dump bed at the rear. A dumper, however, uses a reversed layout and usually lacks any sort of a closed compartment for the driver. The front part of a dumper that can contain materials is referred to as a skip. This skip is typically able to tip forward so that the materials contained within it can be dumped out, which is where the vehicles derive their name. Most skips tilt forward to dump the materials, though some are available that can lift the materials up before dumping or swivel from side to side.
Dumpers can also resemble front loaders, which are another type of tractor. Unlike a front loader, the skip of a dumper usually can not function as a scoop to gather materials. Instead, construction debris or other items are placed into the skip by another machine, sometimes by a backhoe or front loader.
Most dumpers are diesel powered, and early models often used a single cylinder engine that was started with a hand crank. These early units could usually carry between one and two tons of material (900 to 1,800 kg), and the skips were operated manually. The driver could release a latch that let the skip tilt forward and dump its contents. Since there were no hydraulics involved, the skip then had to be lifted back into place manually.
Later designs can handle upwards of ten tons (9,000 kg) and typically use hydraulics to operate the skips. Dumpers are still commonly powered by diesel engines, though larger, multiple cylinder motors are typically used. Most dumpers steer by articulating in the middle, which is known as pivot steering. Even though modern dumpers typically do not have closed cabs, they commonly use some form of rollover protection for the safety of the driver.