belt drives Flashcards
What is the difference between a friction drive and a positive drive belt
Flat belts rely only on friction for their gripping action and need good tension to prevent slip[page
Positive drive belt are everything else that’s not a v belt. They transmit power by positive engagement of belt teeth with pulley teeth, much like a chain drive
Why are V belts considered a better form of friction drive than flat belts
V-belts use the WEDGE for mechanical advantage and require much less tension
What is a match number, and what do the numbers mean
provide a way to match exaactly the V belts used in a MULTIPLE V-belt drive.
50 means it is exactly the circumference it was designed to be.
Each digit represent 1/16 inch
A b90 belts with a match of 44 is a 90 inch belt minus 6/16 inch
What are the advantages of using a narrow groove V belt
.-can handle more power
-uses smaller diameter sheaves
more economical
Can narrow groove V belts use the same sheaves as the classical V belts when you are replacing them? Why or why not?
.NO
The angle of the sides of the sheaves where the V-belts ride is not the same
What are the advantages of cogged V belts
.-DO NOT CONFUSE WITH SYNCHRONOUS BELTS
Notches in the belt provide greater flexibility better heat dissipation smaller sheaves longer life more horsepower more effeicent
What is a banded V belt, and what advantages do they provide
banded V belts are individual V belts with a common back to to share equally the power and load
used for high vibration, shock loads, or misalignment cause belts to whip, flip or turn over
Where would you use fractional horsepower V belts.
- Light duty use with smaller sheaves
- used for infrequent or intermittent use rather than continuous use
What is the main advantage of using v ribbed belts over coneventional belts
.combine the power transmission of conventional v belts with the flexibility of flat belt drives.
handle up to 2,000 horsepower
VVVVVVVVV
How would you identify cogged V belts and ribbed V belts
.cogged v belts go side to side
ribbed v belts go PARRALLEL
How do variable speed V belts work and what is the difference in construction between a variable speed V belt and a conventional V belt
Variable speed belts are wider than conventional V belts and have cogged grooves running perpendicular
It works with sheaves that have movable sides so the ratio changes as the speed changes.
Name three common types of industrial sheave mountings
Press fit
Taper-lock-type compression bushing
Quick Disconnect-type compression bushing
Why should belt dressing not be used
.they are detrimental to the life of the v belt
Belt dressings increase traction by chemically softening the rubber.
It’s a quick fix
What is the ideal v belt tension
Lowest tension at which the belt will not slip under PEAK load conditions
HOw often should you check v belt tension and alignment under normal operating conditions
Every 1,000 hours of use.
