|Classification Hand tool|
|Used with Wedge; hammer wrench|
A sledgehammer is a tool with a large, flat, often metal head, attached to a lever (or handle). The size of its head allows a sledgehammer to apply more force than other hammers of similar size. Along with the mallet, it shares the ability to distribute force over a wide area. This is in contrast to other types of hammers, which concentrate force in a relatively small area.
The word sledgehammer is derived from the Anglo Saxon "slægan", which, in its first sense, means "to strike violently". The English words "slag", "slay", and "slog" are cognates.
The handle can range from 50 centimetres (1 ft 8 in) to a full 1 metre (3 ft 3 in) long, depending on the mass of the head. The head mass is usually 1 to 3 kilograms (2.2 to 6.6 lb). Modern heavy duty sledgehammers come with 10 to 20 pounds (4.5 to 9.1 kg) heads. Sledgehammers usually require two hands and a swinging motion involving the entire torso, in contrast to smaller hammers used for driving in nails. The combination of a long swinging range, and heavy head, increases the force of the resulting impact.
Sledgehammers are often used in destruction work, for breaking through drywall or masonry walls. Sledgehammers are seldom used in modern mining operations, particularly hand steel. Sledgehammers are also used when substantial force is necessary to dislodge a trapped object (often in farm or oil field work), or for fracturing concrete. Another common use is for driving fence posts into the ground. Sledgehammers are used by police forces in raids on property to gain entry by force, commonly through doors. They were and still are commonly used by blacksmiths to shape heavy sections of iron. The British SAS counter terrorist team used sledgehammers to gain access to rooms during the 1980 Iranian Embassy Siege. However, today they use a tool called a "dynamic hammer".
Another iconic use of sledgehammers is for driving railroad spikes into wooden sleepers during rail construction. When the two ends of the Union Pacific railroad were joined at Promontory, Utah, Leland Stanford hammered a golden spike into a tie with a silver hammer. Sledges used to drive spikes for rails had curved heads that came down to a "beak" that was only about one inch across. The shape meant that drivers needed to be accurate, and spot where the spike hit was often not much larger than a dime. Anything larger would hit the plate or the tie. The curved head kept the handle away from the rail, as the spikes were driven with the rail between the spike and the driver. These are often called spike mauls.
A drilling hammer, club hammer, lump hammer, crack hammer, mini-sledge or thor hammer is a small sledgehammer whose relatively light weight and short handle allow single-handed use. It is useful for light demolition work, driving masonry nails, and for use with a steel chisel when cutting stone or metal. In this last application, its weight drives the chisel more deeply into the material being cut than lighter hammers. Club hammers are common on the British inland waterways for driving mooring pins into the towpath or canal bank.
Post mauls are similar to sledgehammers in shape, but are meant to drive wooden fence posts or tree stakes into the earth. Newer mauls have broad, flat circular faces that are significantly larger in diameter than the body of the head (where the handle attaches). Older post mauls are significantly larger than sledgehammers like their newer counterparts except the outside diameter (body) of older post maul designs remained the same large diameter as that of the faces of the hammer from one side to the other side. Sledgehammers usually have octagonal faces that are the same diameter or slightly smaller than the body of the head, and they are not nearly as large in overall diameter as a post maul.