A crossbow is a ranged weapon using an elastic launching device consisting of a bow-like assembly called a prod, mounted horizontally on a main frame called a tiller, which is hand-held in a similar fashion to the stock of a long gun. Crossbows shoot arrow-like projectiles called bolts or quarrels. A person who shoots crossbow is called a crossbowman, an arbalister or an arbalist.
Mechanical advantage is a measure of the force amplification achieved by using a tool, mechanical device or machine system. The device trades off input forces against movement to obtain a desired amplification in the output force. The model for this is the law of the lever. Machine components designed to manage forces and movement in this way are called mechanisms. An ideal mechanism transmits power without adding to or subtracting from it. This means the ideal machine does not include a power source, is frictionless, and is constructed from rigid bodies that do not deflect or wear. The performance of a real system relative to this ideal is expressed in terms of efficiency factors that take into account departures from the ideal.
A pulley is a wheel on an axle or shaft enabling a taut cable or belt passing over the wheel to move and change direction, or transfer power between itself and a shaft. A sheave or pulley wheel is a pulley using an axle supported by a frame or shell (block) to guide a cable or exert force.
A fishing reel is a hand-cranked reel used in angling to wind and stow fishing line, typically mounted onto a fishing rod, but may also be used on compound bows or crossbows to retrieve tethered arrows when bowfishing.
A machine is a physical system that uses power to apply forces and control movement to perform an action. The term is commonly applied to artificial devices, such as those employing engines or motors, but also to natural biological macromolecules, such as molecular machines. Machines can be driven by animals and people, by natural forces such as wind and water, and by chemical, thermal, or electrical power, and include a system of mechanisms that shape the actuator input to achieve a specific application of output forces and movement. They can also include computers and sensors that monitor performance and plan movement, often called mechanical systems.
A winch is a mechanical device that is used to pull in or let out or otherwise adjust the tension of a rope or wire rope.
A block and tackle or only tackle is a system of two or more pulleys with a rope or cable threaded between them, usually used to lift heavy loads.
A rope is a group of yarns, plies, fibres, or strands that are twisted or braided together into a larger and stronger form. Ropes have tensile strength and so can be used for dragging and lifting. Rope is thicker and stronger than similarly constructed cord, string, and twine.
A crank is an arm attached at a right angle to a rotating shaft by which circular motion is imparted to or received from the shaft. When combined with a connecting rod, it can be used to convert circular motion into reciprocating motion, or vice versa. The arm may be a bent portion of the shaft, or a separate arm or disk attached to it. Attached to the end of the crank by a pivot is a rod, usually called a connecting rod (conrod).
A reel is a tool used to store elongated and flexible objects by wrapping the material around a cylindrical core known as a spool. Many reels also have flanges around the ends of the spool to help retain the wrapped material and prevent unwanted slippage off the ends. In most cases, the reel spool is hollow in order to pass an axle and allow it to spin like a wheel, a winding process known as reeling, which can be done by manually turning the reel with handles or cranks, or by machine-powered rotating via motors.
A capstan is a vertical-axled rotating machine developed for use on sailing ships to multiply the pulling force of sailors when hauling ropes, cables, and hawsers. The principle is similar to that of the windlass, which has a horizontal axle.
The Chapel Inclined Plane is an inclined plane immediately to the south of Chapel-en-le-Frith, High Peak, Derbyshire. The ground here rises sharply and the inclined plane was built to connect the lower and upper levels of the Peak Forest Tramway, which was built and initially operated by the Peak Forest Canal Company. It opened for trade on 31 August 1796.
A Prusik is a friction hitch or knot used to attach a loop of cord around a rope, applied in climbing, canyoneering, mountaineering, caving, rope rescue, ziplining, and by arborists. The term Prusik is a name for both the loops of cord used to tie the hitch and the hitch itself, and the verb is "to prusik" or "prusiking". More casually, the term is used for any friction hitch or device that can grab a rope. Due to the pronunciation, the word is often misspelled Prussik, Prussick, or Prussic.
A windlass is a machine used on ships that is used to let-out and heave-up equipment such as a ship's anchor or a fishing trawl. On some ships, it may be located in a specific room called the windlass room.
A chain is a serial assembly of connected pieces, called links, typically made of metal, with an overall character similar to that of a rope in that it is flexible and curved in compression but linear, rigid, and load-bearing in tension. A chain may consist of two or more links. Chains can be classified by their design, which can be dictated by their use:
It is not clear where and when the crossbow originated, but it is believed to have appeared in China and Europe around the 7th to 5th centuries BC. In China the crossbow was one of the primary military weapons from the Warring States period until the end of the Han dynasty, when armies were composed of up to 30 to 50 percent crossbowmen. The crossbow lost much of its popularity after the fall of the Han dynasty, likely due to the rise of the more resilient heavy cavalry during the Six Dynasties. One Tang dynasty source recommends a bow to crossbow ratio of five to one as well as the utilization of the countermarch to make up for the crossbow's lack of speed. The crossbow countermarch technique was further refined in the Song dynasty, but crossbow usage in the military continued to decline after the Mongol conquest of China. Although the crossbow never regained the prominence it once had under the Han, it was never completely phased out either. Even as late as the 17th century AD, military theorists were still recommending it for wider military adoption, but production had already shifted in favour of firearms and traditional composite bows.
A differential pulley —also called "Weston differential pulley", sometimes "differential hoist", "chain hoist", or colloquially "chain fall"— is used to manually lift very heavy objects like car engines. It is operated by pulling upon the slack section of a continuous chain that wraps around two pulleys on a common shaft. The relative sizing of the two connected pulleys determines the maximum weight that can be lifted by hand. If the pulley radii are close enough, then the load will remain in place until the chain is pulled.
A treadwheel crane is a wooden, human powered hoisting and lowering device. It was primarily used during the Roman period and the Middle Ages in the building of castles and cathedrals. The often heavy charge is lifted as the individual inside the treadwheel crane walks. The rope attached to a pulley is turned onto a spindle by the rotation of the wheel thus allowing the device to hoist or lower the affixed pallet.
A simple machine that exhibits mechanical advantage is called a mechanical advantage device - e.g.:
Rigging is both a noun, the equipment, and verb, the action of designing and installing the equipment, in the preparation to move objects. A team of riggers design and install the lifting or rolling equipment needed to raise, roll, slide or lift objects such as heavy machinery, structural components, building materials, or large-scale fixtures with a crane, hoist or block and tackle.
