belt drive - aastmt
Post on 05-May-2022
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M.Atia 1
Belt Drive
Dr. Mostafa Rostom A. AtiaAssociate Prof.
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Belt Drive
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Belt types
Crowned pulleys are used for flat beltsGrooved pulleys, or sheaves are used for round and V belts. Timing belts require toothed wheels, or sprockets.
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Flat Belt
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Belt Geometry
Open Belt
Crossed Belt
ฮธ : Angle of Wrap
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Special belt geometry
Quarter-twist belt drive
Clutch-like belt drive
Variable speed belt driveReversed
belt drive
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Force analysis
Tight side
Loose side
F1 > F2
๐น๐น๐๐ = ๐๐๐ท๐ท
๐๐๐๐๐๐ + 1๐๐๐๐๐๐ โ 1
Centrifugal force
Initial force
๐น๐น1 = ๐น๐น๐๐ + ๐น๐น๐๐ 2 ๐๐๐๐๐๐
๐๐๐๐๐๐ + 1
๐น๐น2 = ๐น๐น๐๐ + ๐น๐น๐๐ 2
๐๐๐๐๐๐ + 1
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Allowable tension force
(For leather belt only)
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Useful data
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Crown effect
The higher section of the crowned pulley puts more tension on the rubber band on that side. As a result, the rubber band flexes into a slight arch towards the right. As the rubber band winds onto the pulley, this arch causes the band to always wind further up on the conical section than what was previously wound on. The higher point on the pulley always creates more tension in the belt and causes it to arch in that direction.
With this exaggerated crowned pulley, it takes just a few turns for the rubber band to wander from the edge of the pulley all the way to up the hump. Once the rubber band is on top of the crowned pulley, the maximum tension will be in the middle of it, and it no longer has any reason to arch in either direction.
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Factors influence reliability and Durability
Pulley condition The pulley surface must be smooth (No excessive wear, scuffing or
peeing) No sharp edges on the flanges ( No frayed edges)
Pulley alignment Misalignment causes belt running in extreme position, rubbing on
flanges and worn or frayed edges of belt
Belt tension Too low tension will lead to slipping of the belt an excessive wear and
over heating Very high tension will leads to excessive wear and possible or joint
fraction. There may be a problem, such as over heat, with bearings dueto excessive load
Shift fork Sharp edges causes frayed or worn edges of belts
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V belt
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V belt sections
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V belt metric section
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V Belt and bully sizes
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Belt geometry
Add the Listed Quantity to the Inside Circumference to Obtain the Pitch Length in
The pitch length Lpthe center-to-center distance C
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Power calculations
The design power
Hnom is the nominal power, Ks is the service factor, nd is the design factor. The number of belts, Nb, is the next higher integer to Hd/Ha.
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Power Ratings of Standard V Belts, KW
Belt-Length Correction Factor K2
Angle of Contact Correction Factor K1 for V Drives
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Force calculations
Some V-Belt Parameters
Service Factors KS for V-Belt DrivesThe number of belts, Nb, is the next higher integer to Hd/Ha.
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Life time calculationsT1, T2 : Equivalent tensions due to bending
Durability Parameters for V-Belt Sections
Lp: The pitch length in m
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V Belt power chart, Commercial
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V Belt tension force
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V Belt assembly faults
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Timing belt
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