Chapter 6 - Chains Flashcards
Chains
Transmission occurs by direct contact.
Friction is not a factor.
Most widely used type of mechanical element.
Used for power transmission and materials handling on conveyors.
High Torque, low cost.
Advantages of Chain Drives
No slippage. Carry very heavy loads. 100% Efficiency. Unlimited Shelf life. Not very affected by environment. Repaired/Replaced easily.
Disadvantages of Chain Drives
Only one plane. Need Lubrication. Precise alignment of shafts. Generate High noise. Elongation. Lower Speed. Sprocket needs to be replaced as well if chain not proper.
Chains Materials:
Cast Iron. Powder Metal. Flame-cut Steel Plate. Machined Metal. Plastic. Composites.
Components of a Chain:
Roller Link.
Pin Link.
Roller Link parts:
Roller Link Plate.
Roller.
Bushing.
Pin Link parts:
Pin Link Plate.
Pin.
Types of Chains
Single Stand Roller Chain.
Double Pitch Roller Chain.
Multiple Strand Roller Chain.
Double Pitch Roller Chain
Contains half as many pitches as a regular chain, therefore is lighter and cheaper.
Suitable for long distances.
Chain Nomenclature
Ex: 50 (5/8" pitch, usual properties) Last # means properties: 0 - Normal 1 - Lightweight 5 - Roller less bushing First #s mean #/8" pitch and #/16" width H on the end means Heavy
Double Pitch Chain Nomenclature
Same as Single Chain, but add 20 in the front. Also need to multiply the pitch by 2.
Multiple Strand Roller Chain
Multiples of the same chains put side by side.
Run at high speeds and carry more load.
Sprockets for Multiple Strand Roller Chains
Sprockets can be single-cut (one tooth per link) or double-cut (two teeth per link).
Cuts down on the wear rate by half.
Multiple Strand Roller Chain Nomenclature
Same as for Single or Double, but has a -# so signify the number of chains attached.
Specific Application Data for Chains
Horsepower Shaft speeds Load and power source Shaft Diameters Center Distance Chain Length Space Limitations Surrounding Conditions
Chain and Sprocket Selection Process:
- Service Factor
- Computation of Design HP
- Tentative Chain Selection
- Final selection of roller chain and small sprocket.
- Selection of the large sprocket.
- Drives with higher chain tension or smaller sprocket requirements.
- Chain Length
- Final center distance calculation.
Addition Design Features
Relative Shaft Positions
Lubrication
Chain Castings
Chain Idler
Conveyor Chain
Roller Chain used for pulling loads at slower speeds.
Rated in terms of Breaking Load.
Silent Chains
Has teeth in the chain and engage with the teeth of the sprocket, this creates less impact and results in a quieter operation.
95-99% efficiency.
Silent Chains Nomenclature
- SC302 (Silent Chain, 3/8” pitch, 2/4” width)
2. SC0315 (Silent Chain, 03=3/16” pitch, 15/32” wide)
Engineering Chains Types:
Straight sidebar steel chains(with rollers or roller less).
Offset sidebar steel chains(with rollers or roller less).
Bar-link chains
Welded steel chains
Open barrel steel pintle chains
Chain Sprockets
Very important when selecting the right chain.
Classified as precision or semi-precision.
Sprocket Types
Type A - no hubs Type B - hub on one side Type C - hubs on two sides Type D - has detachable hub Can be Single-cut or Double-cut
Sprocket teeth requirements:
> 100RPM large pitch - >=15 teeth
100RPM small pitch - >=17 teeth
Normal apps >= 19 teeth
Impulse apps >=23 teeth
Chain Lubrication Methods:
Manual (brush, aerosol can)
Drip
Oil Bath
Pressurized Spray
As pitch ^ :
Strength ^
Capacity ^
Weight ^
What must mach between sprockets and chain
Pitch
Most manufactures form even # of _____, but odd # of _____.
Pitches, teeth.
