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Floating Arm Trebuchet
The floating arm trebuchet is a counterweight siege weapon which is a modern variation of the medieval trebuchet. Their defining feature is free movement of an axle on the throwing arm, and a linear drop channel for the counterweight. The design and construction of such machines is a popular project assignment in post-secondary engineering classes. Basic design A traditional trebuchet, which is simple to engineer, consists of an arm resting off-centre on an axle with a hinged counterweight at the short end of the arm.> The difference in the lengths of the two ends of the arm provides mechanical advantage. In contrast, a floating arm trebuchet features an axle on the arm freely moving along a horizontal glide track. This allows for a higher drop height for the counterweight, which is allowed to fall down a sturdy linear vertical "drop channel". The arm is on a moving axle and the torque acts on the entire structure, preventing stalling. The forward motion of the axle as the arm ro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Counterweight
A counterweight is a weight (object), weight that, by applying an opposite force, provides balance and stability of a machine, mechanical system. The purpose of a counterweight is to make lifting the load faster and more efficient, which saves energy and causes less wear and tear on the lifting machine. Counterweights are often used in traction force, traction elevator, lifts (elevators), Crane (machine), cranes and fair, funfair rides. In these applications, the expected load multiplied by the distance that load will be spaced from the central support (called the "tipping point") must be equal to the counterweight's mass times its distance from the tipping point in order to prevent over-balancing either side. This distance times mass is called the Moment (physics), load moment. By extension, a counterbalance force balances or offsets another force, as when two objects of equal weight, power, or influence are acting in opposition to each other. Examples ;Trebuchet: There are fi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Siege Engine
A siege engine is a device that is designed to break or circumvent heavy castle doors, thick city walls and other fortifications in siege warfare. Some are immobile, constructed in place to attack enemy fortifications from a distance, while others have wheels to enable advancing up to the enemy fortification. There are many distinct types, such as siege towers that allow foot soldiers to scale walls and attack the defenders, battering rams that damage walls or gates, and large ranged weapons (such as ballistas, catapults/trebuchets and other similar constructions) that attack from a distance by launching heavy projectiles. Some complex siege engines were combinations of these types. Siege engines are fairly large constructions – from the size of a small house to a large building. From antiquity up to the development of gunpowder, they were made largely of wood, using rope or leather to help bind them, possibly with a few pieces of metal at key stress points. They could launch s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trebuchet
A trebuchet () is a type of catapult that uses a hinged arm with a sling attached to the tip to launch a projectile. It was a common powerful siege engine until the advent of gunpowder. The design of a trebuchet allows it to launch projectiles of greater weights and further distances than a traditional catapult. There are two main types of trebuchet. The first is the ''traction trebuchet'', or mangonel, which uses manpower to swing the arm. It first appeared in China by the 4th century BC. It spread westward, possibly via the Avars, and was adopted by the Byzantines, Persians, Arabs, and other neighboring peoples by the sixth to seventh centuries AD. The later, and often larger and more powerful, counterweight trebuchet, also known as the counterpoise trebuchet, uses a counterweight to swing the arm. It appeared in both Christian and Muslim lands around the Mediterranean in the 12th century, and was carried back to China by the Mongols in the 13th century. "Although this is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Axle
An axle or axletree is a central shaft for a rotation, rotating wheel and axle, wheel or gear. On wheeled vehicles, the axle may be fixed to the wheels, rotating with them, or fixed to the vehicle, with the wheels rotating around the axle. In the former case, bearing (mechanical), bearings or Bushing (bearing), bushings are provided at the mounting points where the axle is supported. In the latter case, a bearing or bushing sits inside a central hole in the wheel to allow the wheel or gear to rotate around the axle. Sometimes, especially on bicycles, the latter type of axle is referred to as a ''spindle (tool), spindle''. Terminology On cars and trucks, several senses of the word ''axle'' occur in casual usage, referring to the shaft itself, its housing, or simply any transverse pair of wheels. Strictly speaking, a shaft that rotates with the wheel, being either Bolt (fastener), bolted or rotating spline, splined in fixed relation to it, is called an ''axle'' or ''axle shaft ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mechanical Advantage
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. Levers The lever is a movable bar that pivots on a fulcrum attached to or positioned on or across a fixed point. The lever operates by applying forces at different distances from the fulcrum, or pivot. The location of the fulcrum deter ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Torque
In physics and mechanics, torque is the rotational analogue of linear force. It is also referred to as the moment of force (also abbreviated to moment). The symbol for torque is typically \boldsymbol\tau, the lowercase Greek letter ''tau''. When being referred to as moment of force, it is commonly denoted by . Just as a linear force is a push or a pull applied to a body, a torque can be thought of as a twist applied to an object with respect to a chosen point; for example, driving a screw uses torque to force it into an object, which is applied by the screwdriver rotating around its axis to the drives on the head. Historical terminology The term ''torque'' (from Latin , 'to twist') is said to have been suggested by James Thomson and appeared in print in April, 1884. Usage is attested the same year by Silvanus P. Thompson in the first edition of ''Dynamo-Electric Machinery''. Thompson describes his usage of the term as follows: Today, torque is referred to using d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Linear
In mathematics, the term ''linear'' is used in two distinct senses for two different properties: * linearity of a '' function'' (or '' mapping''); * linearity of a '' polynomial''. An example of a linear function is the function defined by f(x)=(ax,bx) that maps the real line to a line in the Euclidean plane R2 that passes through the origin. An example of a linear polynomial in the variables X, Y and Z is aX+bY+cZ+d. Linearity of a mapping is closely related to '' proportionality''. Examples in physics include the linear relationship of voltage and current in an electrical conductor ( Ohm's law), and the relationship of mass and weight. By contrast, more complicated relationships, such as between velocity and kinetic energy, are '' nonlinear''. Generalized for functions in more than one dimension, linearity means the property of a function of being compatible with addition and scaling, also known as the superposition principle. Linearity of a polynomial means that its de ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Potential Energy
In physics, potential energy is the energy of an object or system due to the body's position relative to other objects, or the configuration of its particles. The energy is equal to the work done against any restoring forces, such as gravity or those in a spring. The term ''potential energy'' was introduced by the 19th-century Scottish engineer and physicist William Rankine, although it has links to the ancient Greek philosopher Aristotle's concept of Potentiality and Actuality, ''potentiality''. Common types of potential energy include gravitational potential energy, the elastic potential energy of a deformed spring, and the electric potential energy of an electric charge and an electric field. The unit for energy in the International System of Units (SI) is the joule (symbol J). Potential energy is associated with forces that act on a body in a way that the total Work (physics), work done by these forces on the body depends only on the initial and final positions of the b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kinetic Energy
In physics, the kinetic energy of an object is the form of energy that it possesses due to its motion. In classical mechanics, the kinetic energy of a non-rotating object of mass ''m'' traveling at a speed ''v'' is \fracmv^2.Resnick, Robert and Halliday, David (1960) ''Physics'', Section 7-5, Wiley International Edition The kinetic energy of an object is equal to the work, or force ( F) in the direction of motion times its displacement ( s), needed to accelerate the object from rest to its given speed. The same amount of work is done by the object when decelerating from its current speed to a state of rest. The SI unit of energy is the joule, while the English unit of energy is the foot-pound. In relativistic mechanics, \fracmv^2 is a good approximation of kinetic energy only when ''v'' is much less than the speed of light. History and etymology The adjective ''kinetic'' has its roots in the Greek word κίνησις ''kinesis'', meaning "motion". The dichoto ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pendulum
A pendulum is a device made of a weight suspended from a pivot so that it can swing freely. When a pendulum is displaced sideways from its resting, equilibrium position, it is subject to a restoring force due to gravity that will accelerate it back toward the equilibrium position. When released, the restoring force acting on the pendulum's mass causes it to oscillate about the equilibrium position, swinging back and forth. The time for one complete cycle, a left swing and a right swing, is called the period. The period depends on the length of the pendulum and also to a slight degree on the amplitude, the width of the pendulum's swing. Pendulums were widely used in early mechanical clocks for timekeeping. The regular motion of pendulums was used for timekeeping and was the world's most accurate timekeeping technology until the 1930s. The pendulum clock invented by Christiaan Huygens in 1656 became the world's standard timekeeper, used in homes and offices for 270 years, and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sling (weapon)
A sling is a projectile weapon typically used to hand-throw a blunt projectile such as a stone, clay, or lead " sling-bullet". It is also known as the shepherd's sling or slingshot (in British English, although elsewhere it means something else). Someone who specializes in using slings is called a slinger. A sling has a small cradle or ''pouch'' in the middle of two retention cords, where a projectile is placed. There is a loop on the end of one side of the retention cords. Depending on the design of the sling, either the middle finger or the wrist is placed through a loop on the end of one cord, and a tab at the end of the other cord is placed between the thumb and forefinger. The sling is swung in an arc, and the tab released at a precise moment. This action releases the projectile to fly inertially and ballistically towards the target. By its double-pendulum kinetics, the sling enables stones (or spears) to be thrown much further than they could be by hand alone. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eye Bolt
An eye bolt is a bolt (fastener), bolt with a loop at one end. They are used to firmly attach a securing eye to a structure, so that ropes or cables may then be tied to it. Eye bolts Machinery eye bolts are fully threaded and may have a collar, making them suitable for use with angular loads up to 45°. Eye bolts without a shoulder should not be used for angular loads. Heavy forging, forged eye bolts with a continuous eye may be forged with an integral shoulder, allowing their use for heavy off-axis loads. Eye bolts are often installed into masonry and so versions that form their own anchor bolt are commonly available. Most of these screw into some form of shield anchor. Some lightweight forms are not screwed, but rely on just the pull on the ring itself to expand the anchor. Ring bolts A ring bolt is an eye bolt with a captive ring passing through it. [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
