Belts and Pulleys Flashcards
First Users of Belts and Pulleys
- Ancient Egyptians
- Mesopotamia & Roman Empire
Ancient Egyptian Usage
- lift weights for pyramids
Mesopotamia & Roman Empire Use
- ships and other moving machines
- simple machines
What are the two working principles?
- at least two pulleys with a belt in tension (driver and driven)
- pulling action due to friction
Rope Belt - Types
1) Fiber - 60 meters
2) Wire - 150 meters
Rope Belt Application
Used to transmit large amounts of power using one pulley to another over a large distance
Rope Belt - Primary Advantage
- High frictional grip
- Allow one driver to be connected to several driven systems
Most common used belt
V Belt
First Belt to be used
Round Belt (Rope)
- High localized pressure on top
What was created after the Round Belt?
Flat Belt
- good pressure distribution
- easy for cracks to form due to thin nature
Disadvantages of Flat Belts
- slippage of extremely high
- high tension required
Components of V Belts
- Tension
- Compression
- Tensile Cords
- Envelope
Raw Edge V Belt
- does not have protective envelope
- higher friction
Double V Belt
- all sides of the belt responsible for power transmission
- pulleys on both sides
Cogged V Belt
- purpose of grooves allow for more control for flexibility of the belt
Synchronous/Timing V Belt
- depends on friction & meshing cogs
- grooves for slippage
- used when indexing and weight are important
- thin width
- deep grooves perpendicular
- eliminate excessive heat
Ribbed V Belt
- series of grooves
- increased surface area
- stability in high-vibration
- low mass & high flexibility
- high speed ratio
Multi-Strand/Banded V belt
combine multiple v belts for more HP
What is the horsepower limitations for a single V Belt?
1 - 500 HP
Fractional Horsepower v belts
- transmit less than 1 HP
- low weight and cost
- prefix number is top width of belt
Wedge V Belt
increased surface area of supported tensile cords
Belt Dimensions (4)
- Outer Circumference
- Inner Circumference
- Pitch Length
- Datum Length
Belt Nomenclature XXxXX - Section 1
Outer Circumference
Belt Nomenclature XXxXX - Section 2
Type of Belt
Belt Nomenclature XXxXX - Section 3
Dimensions of the Inner Circumference
For Type A, you subtract ____ from the Outer to get the Inner.
2
For Type B, you subtract ____ from the Outer to get the Inner.
3
For Type C, you subtract ____ from the Outer to get the Inner.
4
For Type D, you subtract ____ from the Outer to get the Inner.
5
For Type E, you subtract ___ from the Outer to get the Inner.
6
