Selection Reference Tables: ISO and ANSI Simplex Chain Parameters
Chain sizing begins with the selection tables. The following reference provides the principal engineering parameters for both ISO B-series and ANSI series simplex chains across the pitch sizes most commonly used in Australian industrial applications. These values conform to ISO 606:2015 and ANSI B29.1 standards.
| Chain No. |
Standard |
Pitch (mm) |
Inner Width (mm) |
Roller Dia. (mm) |
Min. Tensile (kN) |
Max Allow (kN) |
Weight (kg/m) |
| 06B-1 |
ISO |
9.525 |
5.72 |
6.35 |
8.9 |
1.78 |
0.41 |
| 08B-1 |
ISO |
12.70 |
7.75 |
8.51 |
17.8 |
3.56 |
0.70 |
| 10B-1 |
ISO |
15.875 |
9.65 |
10.16 |
22.2 |
4.44 |
0.93 |
| 12B-1 |
ISO |
19.05 |
11.68 |
12.07 |
28.9 |
5.78 |
1.30 |
| 16B-1 |
ISO |
25.40 |
17.02 |
15.88 |
60.0 |
12.0 |
2.71 |
| ANSI 40 |
ANSI |
12.70 |
7.95 |
7.92 |
14.1 |
3.16 |
0.62 |
| ANSI 50 |
ANSI |
15.875 |
9.40 |
10.16 |
21.8 |
4.90 |
0.93 |
| ANSI 60 |
ANSI |
19.05 |
12.57 |
11.91 |
31.1 |
6.22 |
1.30 |
| ANSI 80 |
ANSI |
25.40 |
15.88 |
15.88 |
57.8 |
11.6 |
2.60 |
The Complete Simplex Chain Sizing Process
Correct chain sizing follows a structured sequence. Skipping or shortcutting any step risks specifying a chain that technically passes the calculation but fails in service because the dynamic loading, geometry, or environment was not fully considered. The following eight steps represent complete engineering practice for Australian industrial chain drive sizing.
1
Identify the Transmitted Power
Record the motor rated power (kW) and the fraction transmitted through the chain drive. If the chain drive takes all motor output: Transmitted Power = Motor kW × motor efficiency (typically 0.92–0.96). If a gearbox precedes the chain: use the gearbox output power (motor kW × gearbox efficiency, typically 0.97–0.99 for helical).
2
Determine the Service Factor
Select from the standard classification table: 1.0 (smooth uniform load, ≤10 hrs/day); 1.3 (moderate shock, ≤16 hrs/day); 1.5 (moderate shock, >16 hrs/day or heavy shock, ≤10 hrs/day); 1.7 (heavy shock, ≤16 hrs/day); 2.0 (heavy shock, >16 hrs/day, critical drive). Design Power = Transmitted Power × Service Factor.
3
Establish Driver Sprocket RPM
Identify the RPM at the chain drive input shaft — the gearbox output shaft for most industrial drives. This is not the motor speed. For motor-driven without a gearbox: driver RPM = motor RPM × any coupling ratio. Confirm this with the nameplate or direct measurement with a tachometer if uncertain.
4
Select Chain Pitch from Power Table
Enter the power rating chart at the driver RPM and move across to find the chain size whose rated capacity at that speed equals or exceeds the Design Power. Where multiple chains qualify, select the smallest pitch — smaller pitch means lighter weight, higher speed capability, and less polygon-effect vibration at equivalent chain velocity.
T (N) = Design Power (W) ÷ Chain Velocity (m/s). Chain Velocity = Pitch (m) × Driver Sprocket Teeth × Driver RPM ÷ 60. Confirm T < Allowable Load from the specification table. If T exceeds the allowable load, either increase the velocity (larger driver sprocket) or step up to the next chain pitch.
6
Size Sprockets and Set Velocity Ratio
Driver sprocket: minimum 17 teeth (21+ for precision drives). Velocity ratio = Driven sprocket teeth ÷ Driver sprocket teeth. Maximum 6:1 in a single chain stage — above this, use two chain stages or a gearbox stage to achieve the required ratio without excessive large-sprocket peripheral speed.
Chain length in pitches: L = 2C + (z₁+z₂)/2 + (z₂-z₁)²/(4π²C), where C = centre distance in pitches, z₁ = driver teeth, z₂ = driven teeth. Round up to the nearest even number. Convert back to metres: L (m) = L (pitches) × pitch (m). Add one connecting link.
8
Select Lubrication Method and Confirm Series
Assign lubrication method based on chain speed: <200 RPM = manual/drip; 200–600 RPM = drip-feed; 600–1,500 RPM = bath; >1,500 RPM or heavy shock = forced circulation. Confirm series: standard for smooth drives; H (heavy) for shock service factors ≥1.5. Specify connecting link type: spring clip ≤12B-1/ANSI60; press-fit ≥16B-1/ANSI80.
Service Factor Reference: All Australian Application Types
The service factor is the most critical and most frequently misapplied element of chain sizing. Underestimating the service factor results in a chain that technically passes the calculation but operates above its fatigue limit on every shock event — leading to premature failure that appears without obvious cause. The following table covers the full range of Australian application types.
| Load Type |
Application Examples |
≤10 hrs/day |
10–16 hrs/day |
>16 hrs/day |
| Smooth / Uniform |
Centrifugal pumps, fans, blowers, light conveyors |
1.0 |
1.0 |
1.2 |
| Moderate Shock |
General conveyors, machine tools, packaging |
1.3 |
1.4 |
1.5 |
| Heavy Shock |
Crushers, presses, agricultural drives, heavy conveyors starting under load |
1.5 |
1.7 |
2.0 |
| Extreme Shock (Critical) |
Underground mine conveyors starting under full load, kiln drives, high-cycle presses |
1.7 |
2.0 |
2.0–2.5 |
Worked Sizing Example: Aggregate Conveyor Head Drive
The following complete sizing example demonstrates the process for a typical Australian aggregate processing plant conveyor. All values are worked through in sequence to show the calculation chain from input data to final specification.
Application Data
Gearbox Output RPM
120 RPM
Velocity Ratio Needed
3:1
Calculation Steps
1
Transmitted Power:
22 kW × 0.99 (gearbox efficiency) = 21.8 kW
2
Service Factor (moderate shock, 16 hrs/day):
1.4 → Design Power = 21.8 × 1.4 = 30.5 kW
3
Chain selection from power table at 120 RPM:
16B-1 rated capacity at 120 RPM ≈ 35 kW. Exceeds 30.5 kW ✓. Select 16B-1.
4
Verify working tension:
Chain velocity = 0.02540 × 19 × (120÷60) = 0.965 m/s. Working tension T = 30,500 ÷ 0.965 = 31.6 kN. Allowable = 12.0 kN. Exceeds allowable! Increase driver teeth to 21: v = 0.02540 × 21 × 2 = 1.067 m/s; T = 30,500 ÷ 1.067 = 28.6 kN. Still exceeds 12.0 kN. Step to 20B-1H: allowable load 22.4 kN. With 19T driver: v = 0.03175 × 19 × 2 = 1.208 m/s; T = 30,500 ÷ 1.208 = 25.2 kN. Still exceeds! Increase to 21T: v = 0.03175 × 21 × 2 = 1.334 m/s; T = 30,500 ÷ 1.334 = 22.9 kN. Remains slightly above 22.4 kN allowable. Use 24T driver: v = 0.03175 × 24 × 2 = 1.524 m/s; T = 30,500 ÷ 1.524 = 20.0 kN ✓. Final selection: 20B-1H with 24T driver, 72T driven sprocket.
5
Chain length:
C in pitches = 700 ÷ 31.75 = 22.05. L = 2×22.05 + (24+72)/2 + (72-24)²÷(4π²×22.05) = 44.1 + 48 + 2.62 = 94.7 → Round to 96 pitches (even number). Length = 96 × 0.03175 = 3.048 m.
✓
Final Specification:
Chain: 20B-1H (heavy series, ISO). Driver sprocket: 24 teeth. Driven sprocket: 72 teeth. Chain length: 96 pitches (3.048 m). Lubrication: drip-feed ISO VG 150 (120 RPM = mid-speed range). Connecting link: press-fit (20B-1 exceeds 16B-1 threshold). Series check: heavy-series appropriate for moderate shock at 16 hrs/day.
Material and Surface Treatment Selection Guide
Once the pitch and series are confirmed, the material specification is determined by the operating environment. The following decision framework maps Australian industrial environments to the correct chain material and surface treatment.
🏭Standard Industrial
Environment: Dry, clean, indoor, 5–50°C
Specification: Carbon steel, case-hardened pins, sintered bush. Factory oil coating. Standard or heavy series as required by service factor.
🌊Coastal / Marine
Environment: Salt air, humidity, corrosion risk
Specification: Zinc-nickel plated carbon steel for moderate exposure. SS316 stainless for direct marine spray. Regular corrosion-inhibiting oil application required with carbon steel.
🍎Food / Pharma
Environment: Wash-down, chemical cleaning agents
Specification: SS304 (food contact zones) or SS316 (high-chloride wash). Sealed sintered bush, H1-registered lubricant or maintenance-free. FSANZ-compliant material declarations.
💨Dusty / Abrasive
Environment: Grain dust, mineral dust, cement
Specification: Self-lubricating sintered-bush chain. No external oil (reduces particle adhesion). Enclosure where feasible. PTFE dry-film as alternative in extreme dust.
🌡️High Temperature
Environment: Above 80°C, kiln/dryer duty
Specification: Synthetic PAO chain oil ISO VG 100–150. Above 150°C: ceramic-bushed high-temperature chain (custom specification). Carbon steel with alloy pins to 200°C; above this, specialist chain required.
⚗️Chemical Exposure
Environment: Acids, alkalis, solvents
Specification: SS316 for most chemical environments. Duplex SS 2205 or Hastelloy for halide acids or oxidising acids at elevated temperature. Verify chemical resistance of all component materials, including bush and lubricant.
Common Sizing Mistakes and How to Avoid Them
Chain drive sizing errors are rarely random — the same mistakes recur across Australian industrial projects because the correct procedure is not uniformly applied. The following table identifies the most common errors, their consequences, and the check that prevents each one.
| Sizing Error |
Consequence |
Prevention Check |
| No service factor applied |
Chain operates above fatigue limit on every shock event — early failure |
Always select SF from the table before calculating design power |
| Working tension not verified |
Chain passes power table but exceeds allowable load at low speed |
Always calculate T = Design Power ÷ Chain Velocity and compare with allowable load |
| Under 17 teeth on driver sprocket |
Excessive polygon effect, noise, vibration, and tooth wear |
Specify ≥17 teeth (≥21 for speeds above 300 RPM or precision applications) |
| Using motor RPM instead of shaft RPM |
Design power calculation based on wrong speed — incorrect chain selection |
Always verify RPM at the chain drive input shaft, not at the motor nameplate |
| Spring clip on large-pitch heavy-load chain |
Connecting link failure under operating load |
Specify press-fit link for all chains ≥16B-1/ANSI 80 in industrial service |
| Velocity ratio >6:1 in single stage |
Inadequate wrap angle on small sprocket, chain jump risk |
Limit single-stage ratio to 6:1 or use two stages for higher ratios |
For a verified chain sizing calculation on your specific application, contact the engineering team at Gear Drive Australia — we provide technical sizing reviews for Australian industrial drive applications at no charge with any chain order.
Submit your drive parameters — power, RPM, load type, and environment — to our engineering team at Gear Drive Australia for a complete sizing verification and chain specification recommendation.
Frequently Asked Questions
What information do I need to size a simplex chain correctly? +
Six data points are required for a complete simplex chain sizing: (1) Transmitted power in kW — the power at the chain drive input shaft after any upstream gearbox; (2) Chain drive input shaft RPM — not the motor speed, the speed after the gearbox reduction; (3) Required velocity ratio between driver and driven sprocket; (4) Load character classification — smooth, moderate shock, or heavy shock; (5) Daily operating hours — used to select the correct service factor; and (6) Environmental conditions — temperature, humidity, dust, chemical exposure, and any regulatory requirements (food-grade, mining zone classification). With these six inputs, the complete sizing can be performed in sequence. If you are uncertain about the load classification, err towards the more conservative (higher service factor) option — the cost of one size larger chain is consistently lower than the cost of early failure from undersized selection.
How do I select between ISO and ANSI chain for a new installation? +
For a new installation where no legacy equipment constrains the choice, select the standard with the best local supply availability for your pitch range. In Australia, ISO B-series chains (06B through 32B) are more widely stocked than ANSI at smaller pitch sizes, making them the preferred default for new installations below 16B-1. At larger pitches (equivalent to ANSI 80 and above), both standards are reasonably available through specialist distributors. If the facility already has other equipment using one standard, maintain consistency to simplify spare parts inventory. If the new machine is supplied by an American OEM, ANSI chain is likely the design standard and should be followed for compatibility with existing drive components. Technically, both standards deliver equivalent performance at equivalent pitch — the choice is driven by supply, standardisation, and OEM compatibility rather than performance difference.
Why does working tension sometimes exceed allowable load even when the power rating is met? +
The power rating table is calculated at an assumed “optimal” chain speed for each pitch — typically the speed at which the chain-sprocket engagement losses are minimised and the lubrication film is best developed. At speeds below this optimum (which is common in low-speed, high-torque drives), the chain velocity is lower, and the same power is transmitted at a proportionally higher tension. The working tension check uses the actual chain velocity — Design Power (W) ÷ actual chain velocity (m/s) — which gives the true tensile load regardless of speed. When working tension exceeds the allowable load, the correct response is to increase chain velocity by using a larger-tooth driver sprocket (which raises speed without changing the gear ratio much) or to step up one chain pitch (which increases the allowable load). This is why the working tension verification is a mandatory second check after the power rating table selection — the power table alone is insufficient for drives at low chain speeds.
Can I size a simplex chain for a drive where I don’t know the exact power? +
When exact power is unknown — on a new process design, a machine without nameplated drive data, or a replacement where the original records are lost — use alternative methods to estimate transmitted power. Motor current measurement: P (kW) = √3 × Volts × Amps × power factor × motor efficiency. The actual current at rated load gives the actual consumed power, which is the best available approximation of transmitted power. Torque calculation from static analysis: for drives where the load can be characterised (conveyor friction forces, pump head, fan pressure), calculate the torque at the drive shaft and convert to power using P = 2πNT/60,000. Equivalent equipment benchmarking: compare with similar known-power drives in the same application type — a 600 mm belt conveyor handling coal at 15 m/s typically requires 5–15 kW at the head drive, for example. When power is estimated rather than measured, use a service factor at the upper end of the applicable range to provide additional margin for the uncertainty in the power estimate. For critical drives, commission a power measurement before finalising the chain specification.
How do I size a chain for a variable-speed drive? +
For variable-speed drives controlled by a VSD, the chain sizing must be validated at three operating points rather than one. At maximum speed: verify that the chain velocity does not exceed the maximum rated speed for the selected pitch, and that the power at maximum speed is within the chain’s rated capacity. At minimum speed: verify that the working tension (power ÷ chain velocity) at minimum speed does not exceed the allowable load — this is the most common check that catches undersized chains on variable-speed drives. At rated power: this is the standard sizing point and will typically be intermediate between minimum and maximum speed. For drives that operate at low speed under high torque — a common VSD scenario where speed is reduced to manage material flow — the low-speed working tension check is particularly important and is the most likely failure point of a variable-speed drive chain selection that was only sized at the rated-speed operating point. Include the low-speed high-torque condition explicitly in the design power calculation using the service factor appropriate for the load character at that operating point.
What is the maximum velocity ratio in a single simplex chain stage? +
The practical maximum velocity ratio in a single simplex chain stage is 6:1. Above this ratio, the wrap angle on the small (driver) sprocket falls below 90° — meaning fewer teeth are simultaneously in engagement with the chain, each carrying more of the total load. At less than 90° wrap, tooth jump risk increases significantly under any shock loading or tension spike, because insufficient teeth are engaged to resist the momentary overload. For ratios between 5:1 and 6:1, the minimum driver sprocket tooth count should be increased to 21 to provide adequate wrap angle, and the drive should be inspected for tooth skip tendency during initial commissioning at full load. For ratios exceeding 6:1, the solution is either a two-stage chain reduction (each stage ≤6:1, combined ratio up to 36:1) or a gearbox stage for the high-ratio portion followed by a single chain stage for the final reduction. Two-stage chain reductions are common on lower-speed drives in agricultural and processing machinery where cost and simplicity favour chain over gearbox for the entire reduction.
How does chain sizing change for a high-temperature drive? +
High-temperature drives (above 80°C ambient) require modifications to the standard sizing process. In terms of chain capacity: the allowable load for standard chains should be reduced by approximately 10–15% at 100°C and 20–25% at 150°C to account for the reduction in material yield strength and the degraded lubrication film at these temperatures. Apply this de-rating factor to the allowable load in the specification table before comparing with the working tension. For lubrication: select synthetic PAO oil with a high viscosity index and high-temperature oxidation stability — specify the oil’s rated maximum temperature, which should exceed the expected oil-film temperature at the pin-bush interface (typically 20–40°C above ambient chain temperature). For chain material: alloy steel chains maintain their case-hardening up to approximately 180–200°C; above this, custom high-temperature specifications with ceramic components are required. For thermal expansion: on fixed-centre-distance drives at elevated temperature, the chain circuit lengthens measurably — include adequate takeup travel to accommodate both run-in elongation and thermal expansion over the operating temperature range.
How do I calculate the correct centre distance for a simplex chain drive? +
Centre distance for a simplex chain drive is calculated from the chain length formula rearranged to give centre distance from known chain length — but in practice, centre distance is usually set by the machine layout and the chain length is then calculated to fit. For optimal operation, the centre distance should be between 30 and 50 times the chain pitch in most applications — for a 16B-1 chain (25.4 mm pitch), this means 762–1,270 mm. Below 30 pitches, the small sprocket wrap angle reduces substantially and the chain articulates at each sprocket more frequently, increasing wear rate. Above 80 pitches, the unsupported slack strand becomes long enough to resonate at certain operating speeds and may require intermediate chain guides. The ideal centre distance also depends on the velocity ratio — for high ratios (4:1 to 6:1), a longer centre distance improves the wrap angle on the small sprocket, reducing tooth jump risk. Where centre distance is fixed by the machine layout and falls outside the ideal range, compensate with higher tooth count on the small sprocket (for short centres) or intermediate strand guides (for long centres).
Why does my chain always fail at the connecting link? +
Repeated connecting link failure has three possible causes, each with a different corrective action. The connecting link type is wrong for the load level: spring-clip links on chains at 16B-1 or above in heavy-duty service are not rated for the full chain tensile strength and will fail under peak loading. Replace with interference-fit press-fit links. The press-fit link was not correctly installed: if the link press was inadequate for the chain size, the pins were not driven to full interference depth, creating a loose pin that extracts under load. Use a press tool rated for the specific chain size, verify full seating by confirming zero gap between outer plate and pin shoulder, and check pin articulation after pressing. The chain is correctly specified but the installed service factor is insufficient, creating a working tension that exceeds the connecting link’s rated capacity — the link is the weakest point in the chain circuit and fails first. Review and correct the service factor for the application.
