How are Pulleys classified? Flat belt, V-belt and Rope belt pulleys | Fast and Loose Pulleys
Channel: MechanicaLEi
Date: 2019-03-18

Welcome back MechanicaLEi, did you know that many elements like factor of safety, the actual power to be transmitted, and transmission distance help decide the classification of pulleys? This makes us wonder, How are pulleys classified? Before we jump in check out the previous part of this series to learn about what pedestal and footstep bearings are? 
Now, There are three main types of pulleys based on the type of belts that run through them. Flat belt pulleys are designed for light-duty power transmission and high-performance conveying. They are best suited for applications with smaller pulleys and large central distances. These pulleys have a high power transmission efficiency, are cost-effective, and are easy to use and install. A v-belt pulley is a unique mechanical linkage with a cross-section that resembles an isosceles trapezoid. The v-belt and its complementing pulley create the most efficient belt drive known. However, V-belt pulleys are solely used for transmitting power between two parallel axles as misalignment between the axes considerably decreases the efficiency due to friction losses. Round belts are pulleys with a 60-degree V-groove designed to run a circular cross section belt. Round pulleys are only suitable for idler pulleys that guide the belt, or when O-ring type belts are used. The V-groove transmits torque through a wedging action, thus increasing friction enabling round belt pulleys to be used in low torque situations only. 
A fast and loose pulley arrangement is used on shafts to enable a machine to be started or stopped at will. A fast pulley is keyed to the machine shaft while the loose pulley runs freely. To transmit power the belt runs over the fast pulley and when the power is not needed the belt is simply pushed over or bypassed to the loose pulley which then rotates freely. This arrangement of pullies is very important in paper mill industries where stopping of one machine should not interfere with the other machines which are run by the same line shaft. Shown here is one such pulley system with loose pulley on the extreme left. Hence, we first saw How pulleys are classified based on the type of belts that run on them and then went on to see what fast and loose pulleys are.
In the next episode of MechanicaLEi find out what pipe joints are?

Attributions:

Doh De Oh by Kevin MacLeod is licensed under a Creative Commons Attribution license (https://creativecommons.org/licenses/by/4.0/)
Source: http://incompetech.com/music/royalty-free/index.html?isrc=USUAN1100255
Artist: http://incompetech.com/

Subtle Library by Fabian Measures (http://freemusicarchive.org/music/Fabian_Measures/) is licensed under a Creative Commons Attribution license ( https://creativecommons.org/licenses/by/4.0/)
Source: http://freemusicarchive.org/music/Fabian_Measures/Emotion_Music/Subtle_Library

Photo of a pulley taken in the city of Kampen by GK Bloemsma(https://en.wikipedia.org/wiki/nl:Gebruiker:GeeKaa) is licensed under a Creative Commons Attribution license (https://creativecommons.org/licenses/by/3.0/)
Source: https://en.wikipedia.org/wiki/File:PulleyShip.JPG

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