Snow pushers are typically mounted on wheel loaders, skid steers, or backhoes. Backhoes are usually employed together with loaders and bulldozers. Hydraulic systems use high fluid pressure, such as the hydraulic actuators for bulldozers and backhoes. Backhoes and bulldozers worked weeks to dig hundreds of feet of ditching for these utilities. Although less common, compact backhoes are often attached to compact utility tractors. Backhoes attach to a three-point hitch on farm or industrial tractors. Prisoners serve as pallbearers, chisel names in headstones, and dig graves using shovels and backhoes. Backhoes and dump trucks gradually removed the debris and sand from San Blas. In 1947 Wain-Roy Corporation developed and tested the first actual backhoes. The SCT also readied 60 machines, including backhoes, in case of landslides. The trenches were then filled by the special floating backhoes that dug them. Most backhoes are limited to much lower speeds. The first and popular Case Corporation introduced their backhoes in 1957. However, backhoes still are in general use.