A trip hammer is a type of machine used to exert a large amount of force on a small area. It uses a heavy weight raised with a lever. When the device is "tripped," the weight falls cleanly onto a predetermined spot. A trip hammer can strike with more power and precision than a handheld hammer because it is guided mechanically and powered by gravity. This machine was in widespread use in the ancient world, including both China and Europe.
Up and down are the only two movements a trip hammer performs. It can be raised in several different ways. Some are mostly manual, raised by pushing down on the opposite side of a fulcrum. More commonly, trip hammers are raised through the action of cogs, powered by some external machine. Historically, water wheels were the primary source of power for trip hammers. Sometimes animals were also used, and during the medieval era, windmills came to be harnessed for the same purpose. By the time of the Industrial Revolution, steam was used.
The force of gravity always lowers a trip hammer. The trigger for this movement can be manual or automatic. A simple device might have a manual release, allowing for one-time or occasionally repeated uses. More sophisticated machines, used for larger-scale purposes such as pulverizing grain, are more automated.
Trip hammers have served many functions. They were some of the most powerful machines available to ancient China, ancient Rome, and Europe in the Middle Ages. The first uses, in China, were generally related to the production of edible grain and may have occurred as long ago as 1000 B.C. The trip hammer wasn't described in writing, however, until 40 B.C. The Romans used these machines for the same purpose, but they also applied them to mining. Trip hammers could shatter large chunks of ore into smaller pieces, facilitating the extraction of gold and silver. They came to be used for other processes, such as treating wool and making paper, as well.
Power hammers, still in use today, evolved directly from trip hammers. They were invented soon after steam was first used in the process of raising the hammer. The logical next step was the use of steam to add additional force to the downward stroke of the hammer. Power hammers now use additional power, compressed air, and other mechanisms to optimize the use of energy and maximize force. Trip hammers are not currently in widespread use, although they are still sometimes constructed.