在一些特殊的工作场合，如河道清淤工作，希望挖掘机有尽可能大的挖掘半径和挖掘深度。采用长臂挖掘机施工代价较高。因为工作装置的重力将产生倾翻载荷，而一定重量的机型具有一定的允许倾翻载荷。所以，挖掘半径、挖掘深度和斗容量都受到制约。英国Prestan公司于80年代末推出 In some special workplaces, such as river dredging, it is hoped that the excavator will have as large an excavation radius and depth of excavation as possible. The use of long-arm excavators is costly. Because the gravity of the working device will produce a tipping load, a model with a certain weight will have a certain allowable tipping load. Therefore, the radius of excavation, depth of excavation, and bucket capacity are all restricted. UK Prestan Corporation launched in the late 1980s