Chains and Their Applications in Power Transmission

Chains

• Chains are used for power transmission in various applications.
• Various types of chains exist, including decorative chains, ball and chain, transport chains, ladder chains, and roller chains.
• Roller chains use anti-friction roller bearings for power transmission in machinery.
• They are available in various configurations and sizes.
• Conveying chains are used in material handling functions and can include tabletop and mat-top types.
• Offset sidebar chains, pintle chains, mill chains, and drag chains are engineered for extreme power transmission or conveying service.

Roller Chain

• The working load is carried by link plates.
• Pins, rollers, and bushings experience bending and shearing forces from sprockets.
• Large pitch roller chains have limits on operating speed but can transmit higher horsepower.
• They are available in multi-pitch and self-lubricating varieties.

Advantages of Roller Chains

• Inexpensive
• Available in various sizes and lengths.
• Highly efficient.
• Easy assembly and disassembly.
• Versatile.
• Positive engagement.
• Lengths can be adjusted/modified.
• Simple to work with using basic tools.
• Available in multiple configurations.

Disadvantages of Roller Chains

• Lubrication is critical.
• Subject to dirt.
• High maintenance.
• Noisy operation.
• Speed limitations.
• Backlash.

Lubrication

• Lubrication reduces wear between parts, cushions load impact, dissipates heat, retards corrosion, and flushes away contaminant particles.
• The lubricant viscosity needs to be low enough to flow through and over the chain without sticking to components.
• Additives that can coke and leave behind varnish must be avoided.
• Lubrication methods include immersion, drip systems, pump and spray, and brush applicator methods.

Chain Nomenclature

• Roller chain is specified by pitch, width, and roller diameter.
• Pitch is the distance between the centers of adjacent roller pins.
• ANSI standards for roller chain include 40, 50, 60, and 80.
• The first digits in the nomenclature refer to the chain pitch, expressed in eighths of an inch.
• The last digit in the nomenclature can indicate standard chain (0), lightweight chain (1), and bushed chain (5).

Sprocket Nomenclature

• Sprockets are identified based on 2 digits followed by 2-3 letters and 2-3 numbers followed by a fraction.
• The first two numbers indicate the chain pitch.
• The letters indicate the style of hub, and the materials used (stainless steel).
• The last few numbers denote the number of teeth on the sprocket, followed by a fraction representing the bore diameter.
• Sprocket types include plate only, hub one side, hub both sides, and detachable hubs.

Chain Inspection

• Inspect for chain elongation (exceeding 3% requires replacement).
• Check for proper meshing.
• Look for wear on the side of sprocket teeth (misalignment), wear on the working faces (improper lubrication), and hook shapes (replacement is needed).

Chain Alignment

• Ensure parallel and level shafts.
• Verify sprocket axial alignment using a straightedge.
• Allowable out-of-parallelism tolerances exist per sprocket type.

Chain Installation

• Position sprockets close to bearings to reduce overhang.
• Minimize axial float to accommodate thermal expansion.
• Calculate chain length based on pitch diameters and center distance.

Chain Tension

• Tension should be approximately 1.5 inches per 5 inches of tangential distance between sprockets.
• Excessive slack or tension can cause vibration or premature wear.

Silent Chains

• Silent chains utilize an inverted tooth design.
• They consist of toothed link-plates assembled on pin connectors.
• They are typically used for prime movers rated below 50 horsepower.
• Silent chains have a specific nomenclature, generally denoted by "SC" followed by numbers indicating pitch and width. This allows identification of appropriate replacement parts.

Chain Identification

• Roller chain guides are used as identifiers and as functional parts.