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Pulleys and Belt dri
Pulleys and Belt Drives G8
Term | Definition |
---|---|
pulley | a wheel that has an axle mounted to frame or block, one end connected to load and one to lifting force |
pulleys aka | sheaves |
pulley example | sailboat sails |
fixed pulley | block is attached to solid overhead beam, makes it able to support more |
fixed pulley advantages | allows direction of force to be changed |
mechanical advantage of fixed pulley | no advantage |
distance load moves | equal to distance force moves |
moveable pulley | block attached to load, one rope end attached to force and one to fixed spot |
as pulling force is applied, load | moves closer to fixed point |
mechanical advantage of moveable pulley formula | weight/force=MA |
combination pulley | moveable pulley provides mechanical advantage while fixed allows change in direction |
operation of combination pulley | each moveable pulley adds one more rope segment |
mechanical advantage for combination pulleys | count number of strings supporting load |
gear | wheel with teeth designed to drive another gear |
gear trains | multiple heard used together |
gear drive example | speed reduction gearbox |
driver gear | attached to original driver |
driven gear | attaches to driven/output shaft, causes driven gear to turn |
idler gear | any gear between driver and driven gear, changed direction of rotation |
mechanical advantage of gear drive with diameters | diameter of driven gear/diameter of driven gear=gear ratio |
mechanical advantage of gear drive with teeth | number of teeth on driven gear/number of teeth of driver gear |
rotations per minute change due to | different wheel sizes |
larger gear will be____ than small gear but will have ___ | slower, more power |