120 Roller Chain — Strand-Count Comparison
120 is ANSI B29.1 standard roller chain (ISO 24A), 1.5" pitch (38.1 mm). Compare all strand variants below — pitch and outer dimensions are identical across strands; load capacity scales roughly N× with strand count.
Shared Dimensions (all strands)
ANSI B29.1 pins these dimensions to manufacturer-independent values — single- and multi-strand variants of 120 share identical pitch, roller, pin, and plate geometry.
| Designation | ANSI 120 / ISO 24A |
| Pitch | 1.5" (38.1 mm) |
| Roller diameter | 0.875" |
| Width between plates | 1" |
| Pin diameter | 0.437" |
| Plate thickness | 0.187" |
| Plate height | 1.425" |
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Per-Strand Load & Mass
Load capacity and mass scale roughly linearly with strand count. The sprocket must match (multi-strand sprockets carry N parallel tooth tracks). A dash (—) means the manufacturer doesn't publish that value for that strand variant.
| Canonical PN | Strands | Min tensile (lb) | Avg tensile (lb) | Allowable load (lb) | Mass (lb/ft) | Detail |
|---|---|---|---|---|---|---|
| 120-1 | single-strand | 28,125 | 37,480 | 6,830 | 3.98 | 120-1 → |
| 120-2 | double-strand | 56,250 | 74,960 | 11,610 | 7.86 | 120-2 → |
| 120-3 | triple-strand | 84,375 | 112,440 | 17,080 | 11.78 | 120-3 → |
| 120-4 | 4-strand | 112,500 | 149,920 | 22,550 | 15.7 | 120-4 → |
| 120-5 | 5-strand | 140,625 | 187,400 | 26,650 | 19.59 | 120-5 → |
| 120-6 | 6-strand | 168,750 | 224,880 | 31,430 | 23.49 | 120-6 → |
Same-Pitch Cross-Series
Other chain families with identical pitch but different plate geometry — NOT directly interchangeable, but commonly mistaken for each other. The sprocket fits the pitch; the chain envelope differs.