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Binary Cam
The binary cam is a design for the pulley system of a compound bow. Craig Yehle, director of research and development at Bowtech Archery, received a patent for the design on December 11, 2007. Bowtech started equipping its bows with the new cam design in the 2005 model year. Mechanics The binary cam is described as a modified twin cam setup where each cam is slaved to the other via a loop of string connecting the two cams. This is contrasted with a typical twin cam setup where the ends of the bowstring A bowstring joins the two ends of the bow stave and launches the arrow. Desirable properties include light weight, strength, resistance to abrasion, and resistance to water. Mass has most effect at the center of the string; of extra mass in th ... are physically anchored onto each of the bow limbs. As a twin cam system relies on each cam rotating independently, based solely on the force of the string and the resistance of the bow limbs being absolutely symmetrical, there is r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pulley
A pulley is a wheel on an axle or shaft that is designed to support movement and change of direction of a taut cable or belt, or transfer of power between the shaft and cable or belt. In the case of a pulley supported by a frame or shell that does not transfer power to a shaft, but is used to guide the cable or exert a force, the supporting shell is called a block, and the pulley may be called a sheave. A pulley may have a groove or grooves between flanges around its circumference to locate the cable or belt. The drive element of a pulley system can be a rope, cable, belt, or chain. The earliest evidence of pulleys dates back to Ancient Egypt in the Twelfth Dynasty (1991-1802 BCE) and Mesopotamia in the early 2nd millennium BCE. In Roman Egypt, Hero of Alexandria (c. 10-70 CE) identified the pulley as one of six simple machines used to lift weights. Pulleys are assembled to form a block and tackle in order to provide mechanical advantage to apply large forces. Pulleys are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Compound Bow
In modern archery, a compound bow is a bow that uses a levering system, usually of cables and pulleys, to bend the limbs. In general, compound bows are widely used in target practice and hunting. The pulley/cam system grants the user a mechanical advantage, and so the limbs of a compound bow are much stiffer than those of a recurve bow or longbow. This rigidity makes the compound bow more energy-efficient than other bows, as less energy is dissipated in limb movement. The higher-rigidity, higher-technology construction also improves accuracy by reducing the bow's sensitivity to changes in temperature and humidity. The pulley/cam system also confers a benefit called "let-off." As the string is drawn back, the cams rotate. The cams are eccentric rather than round, and so their effective radius changes as they rotate. Each of a compound bow's two cams features two tracks: an inner track which connects to the opposite limb or opposite cam through cables, and an outer track through ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bowstring
A bowstring joins the two ends of the bow stave and launches the arrow. Desirable properties include light weight, strength, resistance to abrasion, and resistance to water. Mass has most effect at the center of the string; of extra mass in the middle of the string slows the arrow about as much as at the ends. String forms Most bowstrings may be described as either simple, reverse-twisted, or looped. Simple strings may be made of any fiber, twisted into a single cord. Such strings have been used in many parts of the world and are still effective and fairly quick to make. However, they tend to be weaker for their weight, and they may also come apart if not kept constantly under tension. They are normally secured to the bow by a knot/round turn and two half-hitches at each end. Reverse-twisted strings are traditional in Europe and North America for most natural materials. Linen and hemp fiber have been widely used. The form is also used for modern materials. A reverse-twisted ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
