How Does a Crossbow Work?

By Paul Bright

Crossbows are a weapon of choice for hunters that like the feel of an arrow but want the ease of using a gun. Crossbows have been around for thousands of years, first as a weapon but now as an item of sport. The basic crossbow design starts with the holding stock, which resembles the stock of a rifle. On the stock is a slot wide enough to hold the crossbow's arrow, which is known as a bolt. Bolts are smaller than arrows but are much heavier, sometimes even made of metal. At the front of the stock is the bow, which is attached horizontally. The string of the bow draws back to the end of the bolt and is held in place by a special lever called a sear. The sear is attached to a trigger.

Weapon of Choice

Crossbows are a weapon of choice for hunters that like the feel of an arrow but want the ease of using a gun. Crossbows have been around for thousands of years, first as a weapon but now as an item of sport. The basic crossbow design starts with the holding stock, which resembles the stock of a rifle. On the stock is a slot wide enough to hold the crossbow's arrow, which is known as a bolt. Bolts are smaller than arrows but are much heavier, sometimes even made of metal. At the front of the stock is the bow, which is attached horizontally. The string of the bow draws back to the end of the bolt and is held in place by a special lever called a sear. The sear is attached to a trigger.

Early Bows

The first crossbows were invented in two places, China and Mongolia, at the same time. The first crossbow was mentioned around 500 B.C. in Chinese literature. The famous terra cotta army statues found in Emperor Quin Shi Huong's tomb also contained crossbows. In European history, crossbows were used in warfare during the Battle of Hastings. Crossbow-wielding warriors were able to defeat longbow archers despite the limited range of crossbows, because they carried more velocity when firing bolts and required less training time.

Mechanics and Variations

When the trigger is pulled, the crossbow string is released and pushes the bolt forward at high rates of speed. Modern crossbows can fire up to 405 feet per second, according to bowtecharchery.com (see Resources below). That works out to be about 276 mph. This velocity comes from the draw of the bow. Crossbows may have shorter bows than those of longbows, but the kinetic energy is much stronger because of the compact nature and reliance on mechanical methods to hold the bolt in place versus human strength for a longbow. Crossbows with a 700-lb. draw fire at the same feet-per-second velocity rate as longbows with 80-lb. draw weight. Variations of the crossbow include recurve crossbows, which carry more power, but are noisier and can add more wear and tear on the crossbow parts. Compound crossbows require less strength to hold because the pulley system is like that of compound longbows. The pulleys do more work of adding velocity to the bolt when the trigger is pulled. The Chinese even invented a repeating crossbow that used a gravity-fed box to constantly load arrows into the bolt-holder.

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