Hydraulic tools use fluid pressure for smoother performance and higher force than air- or electric-powered tools. Torque wrenches apply a set force to tighten and loosen fasteners. Cable cutters shear cable without flattening, splaying, or fraying the ends. Cable crimping heads compress connectors onto cable. Pipe cutters snap through cast iron, tile, and other soil pipe. Pipe benders curve conduit and pipe to the desired angle. Impact wrenches produce a rotate-and-thrust action to turn fasteners and drill holes. Impact hammer drills spin and vibrate bits to cut holes in concrete, steel, and other materials. Chain saws and pruners cut back overgrowth and remove dead branches from trees and shrubs. Paving breakers use their heft and power to demolish concrete and other hard materials. Sign post drivers sink poles and posts into the ground. Tampers pummel loosely packed fill to compact it. Valve exercisers repeatedly open and close valves to prevent stiffening or seizing.