Wheel and axle

src: museumachines.weebly.com

wheels and axles are one of six simple machines identified by Renaissance scientists who took pictures of the Greek text on technology. Wheels and axles consist of wheels attached to smaller shafts so that these two parts rotate together in which force is transferred from one to another. Hinges or bearings support the shaft, allowing rotation. It can strengthen strength; a small force applied to the large wheel rim can move larger loads attached to the shaft.

Wheels and axles can be seen as lever versions, with a driving force applied tangentially to the perimeter of the wheel and the load force applied to the axle, respectively, which is balanced around the hinges which are the fulcrum. The mechanical advantage of the wheel and the shaft is the ratio of the distance from the fulcrum to the applied load, or what is equal to the diameter ratio of the wheel and the shaft. The main application is wheeled vehicles, where wheels and axles are used to reduce the friction of vehicles moving with the ground. Other examples of devices that use wheels and axles are hats, belts and gears.

Video Wheel and axle

Histori

The Halaf culture 6500-5100 BC has been credited with the early depiction of wheeled vehicles, but this is doubtful as there is no evidence of Halafian using wheeled vehicles or even pottery wheels.

One of the first applications of wheels to emerge is the pottery wheel, which is used by prehistoric culture to make clay pots. The earliest type, known as "tournettes" or "slow wheels", is known in the Middle East in the 5th millennium BC (one of the earliest examples found in Tepe Pardis, Iran, and dated 5200-4700 BC). It is made of stone or clay and secured to the ground with a peg in the middle, but it takes effort to change. The correct wheel (spinning free) seems to be used in Mesopotamia in 3500 BC and probably early in 4000 BC, and the oldest surviving example, found in Ur (modern Iraq), is estimated to be around 3100 BC.

Wheeled vehicle evidence emerged in the second half of the 4th millennium BC, almost simultaneously in Mesopotamia (Sumerian civilization), North Caucasus (Maykop culture) and Central Europe (Cucuteni-Trypillian culture).

A good initial description of wheeled vehicles (carts - four wheels, two aces) is in a Bronocice pot, a ca. 3635-3370 BCE ceramic vase, excavated in the Funnelbeaker cultural settlement in southern Poland.

The oldest wooden wheel example and its axle was discovered in 2002 in Ljubljana Marshes about 20 km south of Ljubljana, the capital of Slovenia. According to radiocarbon dating, it is between 5,100 and 5,350 years old. The wheels are made of ash and oak and have a radius of 70 cm and a 120 cm long axle and are made of teak wood.

In Roman Egypt, the Hero of Alexandria identified wheels and shafts as one of the simplest machines used to lift weights. It is considered in the form of a loop machine consisting of a crank or pulley connected to a cylindrical barrel that provides a mechanical advantage to rotate the rope and lift the load like a bucket from a well.

Maps Wheel and axle

Mechanical advantages

A simple machine called a wheel and axle refers to an assembly formed by two discs, or cylinders, of different diameters installed so that they rotate together around the same axis. The thin stem that needs to be changed is called the axle and the wider object is fixed on the axle, where we apply the force called the wheel. Tangential forces applied to the periphery of large disks can exert a greater force on the load attached to the shaft, achieving mechanical advantage. When used as wheeled wheels, smaller cylinders are wheel shafts, but when used in winch, winch and other similar applications (see the medieval mining lift to the right) smaller cylinders may be separated from the axle mounted on the bearings. It can not be used separately.

Assuming the wheel and the axle do not eliminate or store energy, which has no friction or elasticity, the power input by force applied to the wheel must equal the output power on the axle. When the wheel and the shaft system rotate around the cushion, the point on the circumference, or edges, the wheel moves faster than the point on the circumference, or the edge, the shaft. Therefore, the force applied to the edge of the wheel must be less than the force applied to the shaft edge, since power is the product of strength and speed.

Let a and b be the distance from the center of the bearing to the edge of the wheel A and the shaft B. > F _A is applied to the edge of the wheel A and the style F _B is output, so the speed points A and B are given by a/b , so the output style ratio to input style, or mechanical excellence, provided by

${\ displaystyle MA = {\ frac {F_ {B}} {F_ {A}}} = {\ frac {a} {b}}.} Â Â$

The mechanical advantages of simple machines such as wheels and axles are calculated as the ratio of resistance to effort. The greater the ratio the greater the multiplication of force (torque) created or the distance achieved. By varying the radius of the wheel and/or wheel, the amount of mechanical gain can be obtained. In this way, wheel sizes can be upgraded to an uncomfortable level. In this case a system or combination of wheels (often toothed, ie gears) is used. As wheels and axles are levers, wheel and axle systems such as compound levers.

The ideal mechanical advantage

Keuntungan mekanis dari roda dan poros tanpa gesekan disebut keuntungan mekanis yang ideal (IMA). Ini dihitung dengan rumus berikut:

${\ displaystyle \ mathrm {IMA} = {F_ {\ text {out}} \ over F _ {\ text {in}}} = {\ mathrm {Radius} _ { \ text {wheel}} \ over \ mathrm {Radius} _ {\ text {axle}}}}  ÂÂ$

Keuntungan mekanis yang sebenarnya

Semua roda sebenarnya memiliki gesekan, yang menghilangkan sebagian daya sebagai panas. Keuntungan mekanis yang sebenarnya (AMA) dari roda dan poros dihitung dengan rumus berikut:

${\ displaystyle \ mathrm {AMA} = {F_ {\ text {out}} \ over F _ {\ text {in}}} = \ eta \ cdot {\ mathrm { Radius} _ {\ text {wheel}} \ over \ mathrm {Radius} _ {\ text {axle}}}}  ÂÂ$

dimana

${\ displaystyle \ eta = {P_ {\ text {out}} \ over P _ {\ text {in}}}}  ÂÂ$ adalah efisiensi roda, rasio output daya ke input daya

src: le-www-live-s.legocdn.com

Referensi

src: images-na.ssl-images-amazon.com

Sumber Daya Tambahan

Basic Machines and How They Work, USA. Navy Personnel Bureau, Courier Dover Publications 1965, pp.Ã, 3-1 and following online preview

Source of the article : Wikipedia