The traditional rectangle dump box is still an attractive alternative in select applications. "You do have that full floor. You are going to get maximum spread with it," says Paulsen.
Miller adds that a traditional rectangular dump box offers a lower center of gravity and shorter side heights for the same capacity compared to half-round of semi-elliptical bodies.
Traditional rectangular bodies also allow the use of double-wall construction. "In situations where the application is extreme and they are concerned with the outside appearance of the body, a double-sided body keeps visible damage to the body on the inside," says Miller.
But most rectangular bodies require additional bracing. "On a typical square body, either vertical or horizontal side braces are used to support the sides," says Miller. "In severe applications, both are used to add strength." This adds weight. The flat floor of the traditional dump body is also more susceptible to dents and dings from direct impacts.
And the shape and construction may result in an opportunity for corrosion. "On the traditional, there are more corners, more welds, more opportunities for corrosion to start," says Paulsen.
With the half-round body, the steel is actually formed into a semi-circular shape. The curved floor of the half-round body stands up to impacts better than the flat floor of a traditional rectangular dump body. "It is a strong body," says Gettis.
The curved shape means that the force generated by the material is deflected when it is dropped into the body, as opposed to a flat floor that takes a direct impact. This design doesn't require crossmembers, which translates into a lighter body that can handle more payload.
Clean-out is enhanced, as well. "It also promotes a cleaner dump cycle, meaning that material is less likely to stick in the body when dumping," says Miller.
In addition, the shape of the half-round body affects loading and dumping. "The half round puts the load in the center of the body," says Gettis. When you dump the material, it remains in a concentrated pile. "It comes out in the center if you want to keep it in little piles."
However, the half round has limitations if you plan to haul equipment or pallets in the bed. "If you ever want to put anything in your dump bed, you don't have a flat floor," says Paulsen.
Like the half round, the semi-elliptical dump body does not use crossmembers. "The semi-elliptical body has the ability to absorb a pounding and an impact throughout the whole body," says Pick. "The elliptical curve provides memory for the body itself."
Impact forces are deflected in a similar fashion as the half-round body. "If you put a rock in there, it is never going to hit anything square, so the material is not going to take the full blow of the hit," says Paulsen.
The shape of the semi-elliptical also strikes a balance between the traditional rectangular and half-round dump bodies. "You are still going to have flat floors," says Paulsen. "You are still going to be able to haul stuff with it." But it will not offer as much floor space for pallets and larger equipment as a traditional rectangular body.
The shape does mean the load will be carried slightly higher. "Because of the elliptical design, it does raise the load 'center of gravity' on the truck," says Miller. "And in order to maintain a desired cubic yard capacity, it requires the side height of the body to be a little higher. Both are minimal concerns when weighed against the advantages."
The case for crossmembers
Weight versus durability is always a concern, especially when considering crossmembers.
"The drawback to adding crossmembers is additional weight that reduces payload capacity," says Miller.
But there are ways to eliminate crossmembers without affecting the life. "Eliminating the crossmembers, if done correctly, does not sacrifice either durability or longevity," says Miller. "Elliptical-styled dump bodies have a one-piece floor that is made of higher strength steel that allows for the elimination of the crossmembers."