Pulley

Pulley
PulleyShip.JPG
Pulleys on a ship. In this context, pulleys are normally known as blocks.
ClassificationSimple machine
IndustryConstruction, transportation
Wheels1
Axles1

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.

Hero of Alexandria identified the pulley as one of six simple machines used to lift weights.[1] Pulleys are assembled to form a block and tackle in order to provide mechanical advantage to apply large forces. Pulleys are also assembled as part of belt and chain drives in order to transmit power from one rotating shaft to another.[2][3]

Block and tackle

Various ways of rigging a tackle.[4]

A set of pulleys assembled so that they rotate independently on the same axle form a block. Two blocks with a rope attached to one of the blocks and threaded through the two sets of pulleys form a block and tackle.[5][6]

A block and tackle is assembled so one block is attached to fixed mounting point and the other is attached to the moving load. The ideal mechanical advantage of the block and tackle is equal to the number of parts of the rope that support the moving block.

In the diagram on the right the ideal mechanical advantage of each of the block and tackle assemblies[4] shown is as follows:

  • Gun tackle: 2
  • Luff tackle: 3
  • Double tackle: 4
  • Gyn tackle: 5
  • Threefold purchase: 6
Other Languages
Afrikaans: Katrol
አማርኛ: በከራ
العربية: بكرة
aragonés: Carrucha
asturianu: Polea
azərbaycanca: Blok
Bahasa Banjar: Takal
Bân-lâm-gú: Ka-lak
беларуская: Блок (механіка)
беларуская (тарашкевіца)‎: Блёк
Bikol Central: Moton
български: Макара
bosanski: Čekrk
català: Corriola
čeština: Kladka
Cymraeg: Pwli
eesti: Rihmaratas
Ελληνικά: Τροχαλία
español: Polea
Esperanto: Pulio
euskara: Polea
français: Poulie
Gaeilge: Ulóg
galego: Polea
한국어: 도르래
हिन्दी: घिरनी
hrvatski: Kolotura
Ido: Pulio
Bahasa Indonesia: Katrol
íslenska: Talía
italiano: Carrucola
עברית: גלגלת
ಕನ್ನಡ: ರಾಟೆ
қазақша: Шкив
Kreyòl ayisyen: Pouli
Latina: Trochlea
latviešu: Trīsis
lietuvių: Skridinys
magyar: Csiga (gép)
македонски: Чекрк
മലയാളം: കപ്പി
Bahasa Melayu: Kapi
မြန်မာဘာသာ: စက်သီး
Nederlands: Katrol
नेपाली: घिर्नी
日本語: 滑車
norsk: Trinse
norsk nynorsk: Trinse
occitan: Carrèla
Patois: Puli
português: Polia
română: Scripete
Runa Simi: Phiruru
Scots: Pulley
sicilianu: Cùrrula
Simple English: Pulley
slovenčina: Kladka
slovenščina: Škripec
српски / srpski: Чекрк
srpskohrvatski / српскохрватски: Čekrk
suomi: Talja
Tagalog: Kalo
தமிழ்: கப்பி
ไทย: รอก
ತುಳು: ರಾಟೆ
українська: Блок (механіка)
Tiếng Việt: Ròng rọc
文言: 滑輪
Winaray: Mutón
粵語: 轤轆
中文: 滑轮