How Much Torque Can a Roller Chain Carry?

A roller chain drive is limited by the pull the chain can take. Torque is that pull times the pitch radius of the sprocket, so a bigger sprocket or a bigger chain carries more. This page gives the published strength of ANSI roller chain (single, double and triple strand, carbon steel, higher-strength and stainless series), then two calculators: one finds the most torque a chosen chain and sprocket can carry, the other finds which chains can carry a torque you need.

Limits, read first.
  • This is a strength check, not a full drive selection. Above about 160 ft/min chain speed, fatigue, wear and lubrication set the power rating, which depends on speed and sprocket size and comes from the maker’s horsepower tables. Use those tables for a running drive; use this page for slow or intermittent drives and as an upper bound.
  • Not for lifting. The values are for transmission drives. Roller chain is not rated for overhead lifting or for holding a load where its failure could injure someone.
  • The values are one manufacturer’s published ratings (U.S. Tsubaki) plus one distributor listing. Other makers differ by brand and series. The minimum ultimate strength is the ANSI B29.1 figure; the “maximum allowable load” is the maker’s own limit for repeated slow-speed load and already includes a margin.
  • Stainless chain is much weaker than carbon steel chain. Its published allowable load is a fraction of the carbon steel value for the same size, and the makers publish no ultimate strength for it in the sources used here.
  • Multiple strands do not share load evenly, so the allowable load is the single strand value times 1.7 (two), 2.5 (three), 3.3, 3.9 or 4.6, not times the strand count.
  • Connecting links and joints reduce it. A one-pitch offset link is rated at about 65 percent of the table value. Some makers rate a spring-clip link lower. Temperature, corrosion, shock and a worn chain reduce it further.
Chain Strength Reference
Published Strength, Single, Double and Triple Strand
Which number to use. Minimum ultimate strength is the ANSI B29.1 minimum breaking load of a new chain; never design to it. Average tensile strength is what the maker’s test chains actually broke at. Maximum allowable load is the load the maker allows in service at slow speed; it is the number to compare a design load with. Show loads and pitch in:
Std

ANSI Standard Carbon Steel Roller Chain

ANSI no.PitchSingle strandDouble strandTriple strand
Min. ultimateAverage tensileMax. allowableMin. ultimateMax. allowableMin. ultimateMax. allowable
250.250 in7801,0501401,5602382,340350
350.375 in1,7602,5304803,520816*5,2801,200*
400.500 in3,1254,2908106,2501,377*9,3752,025*
500.625 in4,8807,0501,4309,7602,43114,6403,575
600.750 in7,0309,9201,98014,0603,366*21,0904,950*
801.000 in12,50017,6403,30025,0005,610*37,5008,250*
1001.250 in19,53026,4605,07039,0608,619*58,59012,675*
1201.500 in28,12537,4806,83056,25011,611*84,37517,075*
1401.750 in38,28048,5109,04076,56015,368*114,84022,600*
1602.000 in50,00060,63011,900100,00020,230*150,00029,750*
1802.250 in63,28080,48013,670126,56023,239*189,84034,175*
2002.500 in78,125103,63016,090156,25027,353*234,37540,225*
2403.000 in112,500152,14022,270225,00037,859337,50055,675

Single strand values are the maker’s printed values (1). Multiple-strand ultimate and average strengths are the single strand value times the number of strands; the allowable load is the single value times the strand factor (2). The maker prints the multiple-strand values for some sizes (RS25, RS50, RS240); the others are calculated the same way and agree with those.

Super

Super and Ultra Super Series (Higher-Strength Carbon Steel)

ANSI no.SeriesPitchSingle strandDouble strandTriple strandAllowable vs standard
Average tensileMax. allowableMax. allowableMax. allowable
80Super1.000 in19,1004,1807,106*10,450*1.27×
100Super1.250 in28,6006,83011,611*17,075*1.35×
120Super1.500 in41,8008,81014,977*22,025*1.29×
140Super1.750 in55,10012,10020,570*30,250*1.34×
160Super2.000 in70,50015,80026,860*39,500*1.33×
200Super2.500 in113,50021,10035,870*52,750*1.31×
240Super3.000 in165,30029,70050,490*74,250*1.33×
100Ultra Super1.250 in38,5008,800––1.74×

Dimensions are the same as ANSI standard chain, with wider waist link plates, ball-drifted pitch holes and through-hardened pins (4). The maker states a maximum allowable load 25 to 30 percent above standard RS chain; the printed values are 27 to 35 percent above. Ultra Super is stated as 170 percent of standard allowable load, with the size 100 values confirmed (5, 6). Super and Ultra Super chains cannot be coupled to standard chain, and the maker lists no #180. The maker does not publish a minimum ultimate strength for these series.

SS

Stainless Steel Roller Chain

ANSI no.Pitch304 (SS), single304 (SS), double316 (NS), single600 AS, single600 AS, doubleCarbon steel, single (for comparison)SS as a share of carbon
250.250 in264826––14019%
350.375 in591065991182*48012%
400.500 in9920099150300*81012%
500.625 in154308154231462*1,43011%
600.750 in231462231346692*1,98012%
801.000 in3977943975961,192*3,30012%
1001.250 in5731,150–8601,720*5,07011%
1201.500 in858––––6,83013%
1401.750 in1,034––––9,04011%
1602.000 in1,452––––11,90012%
1802.250 in1,918––––13,67014%
2002.500 in2,420––––16,09015%
2403.000 in3,520––––22,27016%

Distributor listing, 304 stainless (reference 8), single strand:

ANSI no.Tensile, as listedWorking load, as listed
403,970250
507,050400
609,700570
8015,850990

Maximum allowable load, as printed by U.S. Tsubaki (3). SS is 304 stainless throughout. NS is 316 stainless with almost no magnetic response (same load as SS, to RS80). AS is a 600-series precipitation-hardened chain with the highest stainless load capacity; the maker lists it single strand only in this table, so the AS double strand value shown is twice the single value and is not a printed figure. The maker lists no average or ultimate strength for stainless chain in this brochure.

A distributor lists 304 stainless chain at a much higher working load (see the last table). The two do not describe the same product or the same rating basis, so compare like with like and ask the maker for the rating of the chain you will buy.

k

Strand Factors, Service Factors and Speed Coefficients

StrandsStrand factor
11.0
21.7
32.5
43.3
53.9
64.6
Chain speedSpeed coefficient
under 50 ft/min1.0
50 to 100 ft/min1.2
100 to 160 ft/min1.4
160 ft/min and overuse the horsepower tables
LoadElectric motor or turbineEngine, hydraulic driveEngine, mechanical drive
Smooth1.01.01.2
Some impact1.31.21.4
Large impact1.51.41.7

Service factors and speed coefficients are the slow-speed selection values of the maker (2). The column assignment of the service factors was read from a scanned catalog table; check it against the maker’s current catalog.

Calculator 1: Maximum Torque for a Chain and Sprocket
Chain and Sprocket → Maximum Torque
Chain
Sprocket
Gives the chain speed, which sets the speed coefficient, and the power. Leave blank for a static or very slow drive.
Strength Basis and Factors
Used for the two ultimate-strength bases only.
Result
Show detailed calculation steps
Calculator 2: Which Chain Carries the Torque I Need
Required Torque → Chain Options
Load and Sprocket
The peak torque the sprocket must transmit, before the service factor.
With a pitch diameter limit each chain gets the most teeth that fit.
Chain Options to Consider
Chains That Carry the Torque
Sorted by pitch (smallest chain first), then by strands, then by series. “Used” is the design tension as a fraction of the allowed tension; the lower it is the more margin there is. A value marked with * is calculated here from the single-strand rating, not printed by the maker.
Show detailed calculation steps
How It Works
\[ D = \frac{P}{\sin(180^\circ/N)},\qquad T_{\text{chain}} = \frac{2\,\tau}{D},\qquad \tau_{\max} = \frac{F_{\text{allowed}}\,D}{2\,k_s\,k_v},\qquad F_{\text{allowed}} = F_{\text{single}}\,k_n \]

D is the pitch diameter of the sprocket for chain pitch P and N teeth, so the chain pull for a torque τ is 2τ/D. The pull must not exceed the allowed load Fallowed, reduced by the service factor ks and, at low speed, the speed coefficient kv. The allowed load of a multiple-strand chain is the single-strand value times the strand factor kn, because the strands do not share the load equally.

Two ways to set the limit

  • Maker’s allowable load. This already carries a margin for repeated loading at slow speed, so the factor of safety on the breaking load is roughly 4 to 5.5 (810 lb allowable against 3,125 lb minimum for RS40, 22,270 lb against 112,500 lb for RS240). Add the service factor for shock.
  • Ultimate strength with your own safety factor. Use this when you have a design code or a customer requirement, for a rarely loaded or static drive. A factor of 5 to 8 on the minimum ultimate strength is typical for a transmission chain; roller chain is not a lifting chain.

Why a bigger pitch is not always the answer

For a given number of teeth, torque capacity grows roughly with the cube of the pitch (the load with the square, the lever arm with the first power). A smaller chain with more strands and a larger sprocket is quieter and cheaper to guard, but costs more in sprockets and weight. The second calculator lists them in order of pitch so you can compare.

References & Important Notices

References

  1. U.S. Tsubaki Power Transmission, ASME/ANSI RS roller chain item pages, RS25 to RS240 (minimum ultimate strength to ANSI standard, average tensile strength, maximum allowable load), and the General Catalog. Values for each standard-series size were read from its item page. Link.
  2. U.S. Tsubaki, Roller Chain General Catalog, “Selection for Slow Speed” (chain speed under 160 ft/min): chain tension T = 33,000 HP / S, service factors (Table 1), multiple-strand factors (Table 2), speed coefficients (Table 3), and the condition T × service factor × speed coefficient ≤ maximum allowable load. Also the offset-link and connecting-link derating notes. Link.
  3. U.S. Tsubaki, Stainless Steel Products brochure: RS stainless steel roller chain (SS, NS and AS series), maximum allowable load and weight, single and double strand. Link.
  4. U.S. Tsubaki, Super Series chain item pages (80SUPERRB to 240SUPERRB): average tensile strength and maximum allowable load; series description (“Maximum Allowable Load 25-30% higher than our standard RS roller chain”). Link.
  5. U.S. Tsubaki, The Complete Guide to Chain, Table 1.5, comparison of ANSI standard chain (RS100: 118 kN average tensile, 22.6 kN allowable) with Ultra Super chain (US100: 172 kN, 39.2 kN). Link.
  6. U.S. Tsubaki, General Catalog, Ultra Super chain page (170 percent of the standard RS allowable load; chains cannot be coupled with RS standard chain; US100 38,500 lb average tensile, 8,800 lb allowable). Link.
  7. ASME B29.1, Precision Power Transmission Roller Chains, Attachments, and Sprockets (ANSI B29.1), the source of the minimum ultimate tensile strength values and chain dimensions. Not consulted directly; values are as printed by the chain maker.
  8. USA Roller Chain, listing of 304 stainless “Mega” series chain #40SS to #80SS (tensile 3,970, 7,050, 9,700 and 15,850 lb; working load 250, 400, 570 and 990 lb). A distributor listing, not a maker’s catalog; rating basis not stated. Link.
  9. U.S. Tsubaki, BS/DIN Roller Chain: Chain Drive Selection, p. A-51 to A-52: selection procedure, service factors (Table I) and multiple-strand factors 1.7 (double) and 2.5 (triple) (Table II). Link.

Important notices

  • Source of the strength values. The standard-series single strand values were read from each chain’s item page in the U.S. Tsubaki catalog (RS25 to RS240), the Super series from the item pages of that series, the stainless loads from the stainless steel products brochure, and the selection factors from the roller chain catalog. The ANSI minimum ultimate strengths are as printed by that maker; ASME B29.1 itself was not consulted.
  • Other manufacturers. Ratings of Renold, Diamond, Rexnord, Regina and others differ, especially for the average tensile and allowable load. Use the rating of the chain you buy. The ISO 606 (B-series, metric) chains are not covered.
  • Derived values are marked. Where this page computes a value (multiple-strand ratings, AS double strand), it says so in the table.
  • Not in the data. Heavy series, double-pitch, nickel-plated, lube-free (Lambda) and food-grade chains have their own ratings which were not confirmed against a printed table and are not shown. Nickel plating and corrosion-resistant coatings are generally rated below plain carbon steel chain by their makers; ask for the rating.
  • No endorsement. No chain maker, distributor or standards body named here has reviewed or approved this page.
  • Reference aid, not a substitute for the maker’s selection. For any drive that is high-speed, high-power, a safety function or hard to replace, have the chain maker or an application engineer confirm the selection.

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