pup A truck and pup is very similar to a transfer dump. It consists of a standard dump truck pulling a dump trailer. The pup trailer, unlike the transfer, has its own hydraulic ram and is capable of self-unloading. Superdump truck A super dump is a straight dump truck equipped with a trailing axle, a liftable, load-bearing axle rated as high as . Trailing behind the rear tandem, the trailing axle stretches the outer "bridge" measurement—the distance between the first and last axles—to the maximum overall length allowed. This increases the gross weight allowed under the federal bridge formula, which sets standards for truck size and weight. Depending on the vehicle length and axle configuration, Superdumps can be rated as high as GVW and carry of payload or more. When the truck is empty or ready to offload, the trailing axle toggles up off the road surface on two hydraulic arms to clear the rear of the vehicle. Truck owners call their trailing axle-equipped trucks Superdumps because they far exceed the payload, productivity, and return on investment of a conventional dump truck. The Superdump and trailing axle concept were developed by Strong Industries of Houston, Texas. Semi trailer bottom dump truck A semi bottom dump, bottom hopper, or belly dump is a (commonly) 3-axle tractor pulling a 2-axle trailer with a clam shell type dump gate in the belly of the trailer. The key advantage of a semi bottom dump is its ability to lay material in a windrow, a linear heap. In addition, a semi bottom dump is maneuverable in reverse, unlike the double and triple trailer configurations described below. These trailers may be found either of the windrow type shown in the photo or may be of the cross spread type, with the gate opening front to rear instead of left and right. The cross spread type gate will actually spread the cereal grains fairly and evenly from the width of the trailer. By comparison, the windrow-type gate leaves a pile in the middle. The cross spread type gate, on the other hand, tends to jam and may not work very well with coarse materials. Double and triple trailer bottom dump truck Double and triple bottom dumps consist of a 2-axle tractor pulling one single-axle semi-trailer and an additional full trailer (or two full trailers in the case of triples). These dump trucks allow the driver to lay