Pulleys
Fixed
Moveable
A fixed pulley is a wheel that has a groove for a rope, cham or belt to go round lt. It rotates around an axle that ls fixed to an immobile surface. This reduces the load. R when elfort, f, is applied
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moveabie pullev has two pulleys —one is fixed while the other can move m a imear direr.tron.
A moveable pulley is balanced when it iulfils this equation: f=r
~
Compound
This is a set of fixed and moveable pulleys, often called a block and tackle. If we use more pulleys it bei.omes more complex, but less effort is needed to move the load
Friction drive
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Th >S >Smade up Of tWO Or mere wheels that are in contact.
• Wheel(II>scalledtheprimary drive wheel When it mi>ves,
it turns or dnvesthe output
wheel (2), causing it to move as well.
velar tyN
• The output wheel rotates >n the opposite d>rection to the primary wheel. If we use more than two wheels, each one rotates in the oppos>te d>rect>on to the i>ne next to it
Pulleys whith belts
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Th e~a are two pulleys or wheels that are a certain d>stance apart
• Th e>r axles are parallel and they rotate simultaneously because of the belt
• Th e rotat>on of one axle >s transm>tted to the other via the connected pulleys
wheel 1 ve>ooty >V,
•
Gearbelts
Cogwheels are sets of wheels that have teeth called cogs.
The>mesh together so that one wheel moves another They transmit a rotary motion between the two r.onner.ted axles, which can be parallel, perpendicular or ublique Some common types of cvlindncal gears are spur gears and helical gears A bevel gear ts an example of a comcal gea
Work gear
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Th i s ts a screw that moves a helical cogwheel which is set perpendicular to the screw
Ea ch time the screw rotates the gear moves I'nrward as many teeth as grooves m the acre~ (normally a small number, I, 2 or 3)
Th is ts used to reduce veloaty as well as serving as a braking system