Power hammers are mechanical forging hammers that use a non-muscular energy source to lift the preparatory hammer to strike and accelerate it over the work being hammered. Also called "open die power forging hammers". They have been used by blacksmiths, bladesmiths, metallurgists, and manufacturers since the late 1880s, replacing the travel hammers.
A typical hydraulic hammer consists of a frame, an anvil and an alternate piston that holds a hammer head or die. The workpiece is placed on the lower anvil or die and the top die or head punches the workpiece. The electric hammer is a direct descendant of the firing hammer, which differs in that the power hammer stores potential energy in an arrangement of mechanical links and springs, in compressed air or steam, and by the fact that it accelerates the piston in the path Descending. This provides more strength than simply allowing the weight to drop. Predecessors such as travel hammers, steam hammers, board or belt hammers, used the power source to lift the hammer or hammer head, but to drop it only under gravity.
The power hammers are classified by weight of moving parts acting directly on the workpiece. This includes the weight of the parts that may consist of upper trunnion, piston, mechanical coupling arms and spring (s) or piston, piston and associated connecting rod (s). The specific design elements are dictated by the power source. The largest electric hammer was powered by steam and was rated at 125 short tons (113 tons).