The Hickok Pruning Lopper, also called a tree shear, is a deceptively simple piece of equipment, its design masking thousands of hours of laboratory and field testing necessary to bring it into production. All that simplicity is based on some very sophisticated principles of cutting dynamics.The Lopper as Lever First, start with the principle of the lever, one of man’s oldest tools. The lopper—or scissor-type lever—is a Class I lever with its fulcrum or pivot poin …