Crossbows developed from hand bows as a more user-friendly option for launching arrows in combat, hunting, and recreational target shooting. While simplification of use also meant a more complex and expensive device than a typical bow, it also meant that just about anyone could pick up a crossbow and be able to shoot accurately with just as little practice. In contrast, for example, typical English longbow archers practiced for many years to effectively use their weapons.
The Components of Crossbows
At their most basic, crossbows consist of a few key parts: the prod, string, tiller, lock, and trigger. There are a number of variations among these components accross European historical crossbows.
The prod is the bow of the crossbow, and the element which, when bent, stores the energy which is used to propel the arrow - or bolt - when released. Early crossbow prods were simply made from single pieces of wood, just like many hand bows. However, the tensile strength - and thus shooting power - of these wooden prods was limited, and they were eventually replaced with prods constructed from a combination of wood, animal horn, and sinew. These bows could be tremendously powerful, sometimes up to 1000lbs in draw weight. They were, however, very susceptible to changes in temperature and moisture which could reduce their effectiveness - and they were also very expensive and time-consuming to produce. Thus, as metallurgy and blacksmithing advanced, steel prods were introduced, which were equally (if not frequently more) powerful than their composite forebears, and relatively quick and cheap to produce. Modern crossbow prods are often made from fiberglass and carbon fiber. At the Modern Armbruster, we use hardened and tempered steel and aluminum prods, as well as fiberglass, in order to reduce the cost and manufacturing time of our crossbows.
Most strings on medieval and Renaissance European crossbows were made from plant-based materials, usually either linen or hemp. These strings were constructed from dozens of individual strands wound together, which increased the tensile strength of the string and also provided a good stout surface to connect with the back of the bolt and push it forward upon release. At the Modern Armbruster, we provide strings made from modern Dacron, a light and strong synthetic fibre used widely in modern archery.
The tiller, or stock, is the largest structural element of the crossbow on which the bow, lock, and trigger are mounted. Tillers developed into a wide variety of shapes and sizes, informed by function, economy, and stylistic considerations. For example, western European tillers were typically square or rectangular in cross section, while those manufactured in central Europe were more rounded or ovoid. At the Modern Armbruster, our flagship bow is based on a German style known as a "Rustung", with an oval cross section and asymmetrical butt that accommodates an ergonomically designed cheek rest.
The Lock and Trigger
Historical crossbows employed a variety of locking mechanisms and triggers to retain and release the string. One of the most simple mechanisms was discovered on an early example of a crossbow found in Sweden. Known as a "Skane lock" (after the province in which it was found), this type of lock is also known as a rising peg system, and consists of three simple components: a notch in the stock to restrain the string, a peg that pushes up against the string through a hole in the stock, and a trigger lever that pushes the peg through the hole, which in turn pushes the string out of its restraining notch, releasing the bow.
Perhaps the most widely used locking mechanism was the rolling nut lock, which utilized a cylindrical roller, typically made from antler and set into the top of the stock. The top of the roller was shaped into two restraining "fingers" which hold the string when spanned, and a notch on the bottom with which the trigger lever would engage to prevent the nut from turning until the trigger was pulled. This highly efficient lock system was combined with a variety of trigger systems - from a simple single axle lever to complex four axle systems found on German hunting bows.