Choosing roller chain for a conveyor system involves more variables than most procurement decisions suggest. The chain size that fits the existing sprocket is rarely sufficient as the only specification criterion — the conveyor loading, speed, environment, and required service life all influence whether that size is actually adequate or whether a different configuration would perform better and cost less over time. This guide provides a structured selection methodology that covers every relevant variable, from initial load calculation through to material and sealing specification for the operating environment.
Step 1: Establish the Conveyor Operating Parameters
Before any roller chain dimension can be evaluated, four operating parameters must be established with reasonable accuracy: the chain pull (the tangential force at the drive sprocket in kilonewtons), the required chain speed (in metres per second), the operating hours per day and days per year, and the nature of the loading — smooth and continuous, moderately variable, or heavy shock with frequent peak loads. Each of these parameters feeds into a different part of the selection calculation.
Chain pull for a horizontal conveyor is typically calculated as: chain pull (kN) = (total material weight on conveyor + chain weight on carrying strand) × friction coefficient of the conveyor surface, plus any incline component for non-horizontal conveyors. For a simple flat conveyor carrying 2,000 kg of material across a 20-metre carrying strand with a coefficient of friction of 0.25 and a chain weight of 15 kg/m (ANSI 80 simplex), the chain pull is approximately: (2,000 + 15 × 20) × 0.25 × 9.81 / 1000 = approximately 5.6 kN. This is the static chain pull before applying the service factor.
Step 2: Apply the Service Factor
The service factor accounts for the dynamic loading conditions that the roller chain will experience in practice. ANSI B29.1 provides service factor tables based on the type of prime mover, the nature of the driven load, and the operating hours per day. For conveyor applications, the relevant service factor values are:
| Loading Character | Service Factor | Example Conveyor Applications |
|---|---|---|
| Smooth — uniform material flow, constant speed, no shock | 1.0 | Flat belt support conveyor, uniform grain auger, packaging line |
| Moderate shock — some variation, occasional starts under partial load | 1.3 | Bucket elevator, screw conveyor, variable-density material conveyor |
| Heavy shock — significant load variation, frequent starts under full load, material jams possible | 1.5–1.7 | Mining belt feeder, apron conveyor, recycling conveyor, crusher feeder |
Multiply the calculated chain pull by the service factor to obtain the design chain pull. For the 5.6 kN example with moderate shock (service factor 1.3): design chain pull = 5.6 × 1.3 = 7.3 kN.
Step 3: Identify Candidate Chain Sizes
Match the design chain pull against the rated working loads for candidate chain sizes. As a starting point, working load should not exceed approximately 20 to 25 percent of the chain minimum breaking load for most conveyor applications — this provides the safety and fatigue margin required for continuous cyclic loading. For ANSI 60 simplex (31.3 kN minimum break load), the practical working load limit is approximately 6.3 to 7.8 kN — our design chain pull of 7.3 kN falls within this range, making ANSI 60 simplex a candidate.
| ANSI Chain | Min Break Load (kN) | Practical Working Load (kN) | Suitable for Design Pull Up To |
|---|---|---|---|
| ANSI 40 | 14.1 | 2.8–3.5 | 3.5 kN |
| ANSI 50 | 21.8 | 4.4–5.5 | 5.5 kN |
| ANSI 60 | 31.3 | 6.3–7.8 | 7.8 kN |
| ANSI 80 | 55.6 | 11.1–13.9 | 13.9 kN |
| ANSI 100 | 87.0 | 17.4–21.8 | 21.8 kN |
| ANSI 120 | 125.0 | 25.0–31.3 | 31.3 kN |
Step 4: Verify Chain Speed Is Within the Pitch Limit
Each chain pitch has a maximum recommended operating speed. At higher speeds, dynamic loads from chordal action and roller impact at sprocket engagement increase with the square of velocity, generating dynamic loads that erode the static working load margin. If the required conveyor speed exceeds the maximum for the candidate pitch, either move to a smaller pitch (and possibly multiple strands) or reduce sprocket size to lower the chain speed.
| ANSI Chain | Max Recommended Speed (m/s) | Suitable Chain Speed Range |
|---|---|---|
| ANSI 40 | 8.0 | Best for light high-speed conveyors |
| ANSI 50 | 6.5 | General industrial conveyors up to moderate speed |
| ANSI 60 | 5.0 | Agricultural and industrial — most common conveyor size |
| ANSI 80 | 3.5 | Heavy conveyors — keep speed below 3.5 m/s |
| ANSI 100 | 2.5 | Heavy slow conveyors — mining, quarry |
| ANSI 120 | 2.0 | Very heavy, very slow drives only |
Step 5: Choose Material and Sealing Specification
Once pitch and strand count are determined, the material and sealing specification is chosen based on the operating environment. Standard carbon steel is correct for clean, sheltered, well-maintained drives. For dusty or contaminated conveyor environments — grain handling, mineral processing, cement plants — O-ring roller chain provides sealed joint protection that dramatically extends service life. For food processing conveyors in product contact zones, stainless steel roller chain with NSF H1 food-grade lubrication is mandatory. For outdoor agricultural conveyors with variable load and shock, sawtooth plate roller chain improves fatigue life where plate cracking has been the historical failure mode.
Step 6: Specify Connecting Link Type
Specify the connecting link type to match the application shock level. For smooth, steady-state conveyor drives, a spring clip connecting link is adequate. For shock-load conveyors — mining feeders, vibrating conveyors, conveyors with frequent start-stop under full load — specify a cottered connecting link. The cottered link provides mechanical retention that resists shock-induced dislodgement that spring clip links cannot reliably withstand.
Smooth conveyor drive
Standard carbon steel simplex, spring clip connecting link. Most economical correct specification for clean, steady-state conveyor applications.
Variable load, dusty environment
O-ring roller chain or self-lubricating chain. Sealed joint protection for dusty grain handling, cement, and mineral processing conveyors.
Shock-load conveyor (mining, crusher feeder)
Heavy duty ANSI H series with cottered connecting link. Heavier plates for fatigue resistance; positive pin retention for shock load conditions.
Food processing conveyor
Stainless steel chain (304 or 316 grade) with NSF H1 food-grade oil. Mandatory for product contact zone compliance with HACCP requirements.
Variable agricultural conveyor
Sawtooth plate chain if plate cracking is the current failure mode; standard chain with improved lubrication if elongation is the failure mode.
EverPower Roller Chains Australia can assist with conveyor roller chain specification for new and replacement drives. Send us your conveyor load, speed, length, and operating environment and our Sydney team will recommend the correct pitch, strand count, and chain type. Call +61 2 9708 3322.
+61 2 9708 3322 | [email protected] | 27 Harley Crescent, Condell Park NSW 2201