Roller Chain/Sprocket Selection of Transmission Roller Chain

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Selection of Transmission Roller Chain

Coefficients Relevant to Selection

Tables 1 through 5 present the coefficients that are relevant to the selection of chains. All values assume smooth operation, and for this reason, they are not suitable for special operating conditions.

Service Coefficient

The transmission performance of chains requires smooth operation for full realization; accordingly, correction will need to be carried out for loading conditions. The service coefficients from the following table are to be used for such condition.

Table 1: Service Condition αU

Multiplex Coefficient

The transmission performance of multiplex chains is determined by applying the multiplex coefficient from the following table to the transmission performance for a single chain.

Multiplicity		Multiplex coefficient
2		1.7
3		2.5
4		3.3

Table 3: Multiplex Coefficient αL

The multiplex performance cannot be achieved by simply multiplying the single-chain performance by the multiplicity.

Unbalanced Load Coefficient

When using two or four chains in a suspension situation or the like, the load applied to chains does not conform to an average value.

For this reason, the unbalanced load coefficient from the following table is to be used to determine the load for each chain.

Suspensions		Unbalanced load Coefficient
2		0.6
4		0.35

Table 5: Unbalanced Load Coefficient αB

Speed Coefficient

As the travel speed of a chain increases, operating conditions become more severe; consequently, the speed coefficient from the following table is used to indicate this severity.

Chain speed		Speed coefficient
~15m/min		1.0
15~30m/min		1.2
30~50m/min		1.4

Table 2: Speed Coefficient αV

Safety Coefficient

The safety coefficient (or safety factor, SF) is determined using the formula shown below, and it should generally be maintained within the 7 to 10 range. However, it is often necessary to raise the safety coefficient for certain usage conditions (i.e., chain speed, ambient temperature, loading method, etc.). Furthermore, any legal requirements must also be implemented at this time.

Chain speed		Safety coefficient
~25m/min		7
25~50m/min		8

Table 4: Safety Coefficient (SF)

Example: Load W1 kgf applied to one of four chains used to suspend an object of weight W = 3,000kgf.

Section Formulae

Chain Length: L (no. of links)

Where Cp is the inter-shaft distance expressed as a pitch;

N1 is the number of teeth on the small sprocket; and

N2 is the number of teeth on the large sprocket.

Chain Speed: v (m/min)

Where p is the chain pitch (mm);

N is the number of teeth on the sprocket; and

r is the sprocket speed (rpm).

Chain Tensile Force for Rated Output: F (kgf)

Where kW is the rated output (kW) and v is the chain speed (m/min).

Corrected Transmission Performance: kW' (kW)

Where kW is the rated output (kW) and

αu is the service coefficient (from Table 1 on page 55).

The chain length L found using the formula presented here should be rounded off to an integer. Note that an offset link will be required when the chain length is an odd number; however, the tooth numbers and inter-shaft distance should be adjusted whenever possible to ensure that calculation produces an even number.

Simple Selection Tables

Mode of Use

These tables allow you to select usable chains based on the small sprocket speed and the transmission performance (corrected).
Example: Selection based on a sprocket speed of 500 rpm and a transmission performance of 5 kW.

(1) Tentatively set the number of teeth on the small sprocket. Here, a value of N = 15 will be used.

Chain number (No.)	Number of teeth	Multiplicity	Speed coefficient
60	15	1	Suitable
50	15	2	Not economic
50	17	1	No reserve in terms of performance

(2) The intersection of small-sprocket speed (horizontal axis) and transmission performance (vertical axis) on the Simple Selection Table for 15 gear teeth appears between No. 50 and No. 60; accordingly, No. 60 is selected.

(3) Evaluate situations for other tooth numbers in the same way, and select a suitable combination of tooth number and chain specification.

Selection of chains from the right side of the triangular sections on the Simple Selection Tables should be avoided whenever possible.

Standard Roller Chains

Number of teeth = 15

Chain number (No.)	Pitch circle diameter (mm)	Outer diameter (mm)
25	30.54	34
35	45.81	51
40	61.08	67
50	76.35	84
60	91.62	101
80	122.17	135
100	152.71	168
120	183.25	202
140	213.79	236
160	244.33	269
180	274.87	303
200	305.42	337
240	366.50	404

Number of teeth = 17

Chain number (No.)	Pitch circle diameter (mm)	Outer diameter (mm)
25	34.56	38
35	51.84	57
40	69.12	76
50	86.39	94
60	103.67	113
80	138.23	151
100	172.79	189
120	207.35	227
140	241.91	264
160	276.46	302
180	311.02	340
200	345.58	378
240	414.70	453

Number of teeth = 19

Chain number (No.)	Pitch circle diameter (mm)	Outer diameter (mm)
25	38.58	42
35	57.87	63
40	77.16	84
50	96.45	105
60	115.74	126
80	154.32	167
100	192.90	209
120	231.48	251
140	270.06	293
160	308.64	335
180	324.12	358
200	385.79	419
240	462.95	502

Number of teeth = 21

Chain number (No.)	Pitch circle diameter (mm)	Outer diameter (mm)
25	42.61	46
35	63.91	69
40	85.21	92
50	106.51	115
60	127.82	138
80	170.42	184
100	213.03	230
120	255.63	276
140	298.24	322
160	340.84	368
180	383.84	413
200	426.05	459
240	511.26	551

Number of teeth = 23

Chain number (No.)	Pitch circle diameter (mm)	Outer diameter (mm)
25	46.63	50
35	69.95	75
40	93.27	100
50	116.58	125
60	139.90	150
80	186.54	200
100	233.17	250
120	279.80	300
140	326.44	350
160	373.07	400
180	419.71	450
200	466.34	500
240	559.61	600

Super Roller Chains

Number of teeth = 15

Chain number (No.)	Pitch circle diameter (mm)	Outer diameter (mm)
80	122.17	135
100	152.71	168
120	183.25	202
140	213.79	236
160	244.33	269
200	305.42	337
240	366.50	404

Number of teeth = 17

Chain number (No.)	Pitch circle diameter (mm)	Outer diameter (mm)
80	138.23	151
100	172.79	189
120	207.35	227
140	241.91	264
160	276.46	302
200	345.58	378
240	414.70	453

Number of teeth = 19

Chain number (No.)	Pitch circle diameter (mm)	Outer diameter (mm)
80	154.32	167
100	192.90	209
120	231.48	251
140	270.06	293
160	308.64	335
200	385.79	419
240	462.95	502

Number of teeth = 21

Chain number (No.)	Pitch circle diameter (mm)	Outer diameter (mm)
80	170.42	184
100	213.03	230
120	255.63	276
140	298.24	322
160	340.84	368
200	426.05	459
240	511.26	551

Roller Chain/Sprocket Selection of Transmission Roller Chain

Selection of Transmission Roller Chain

Coefficients Relevant to Selection

Service Coefficient

Multiplex Coefficient

Unbalanced Load Coefficient

Speed Coefficient

Safety Coefficient

Section Formulae

Chain Length: L (no. of links)

Chain Speed: v (m/min)

Chain Tensile Force for Rated Output: F (kgf)

Corrected Transmission Performance: kW' (kW)

Simple Selection Tables

Mode of Use

Standard Roller Chains

Number of teeth = 15

Number of teeth = 17

Number of teeth = 19

Number of teeth = 21

Number of teeth = 23

Super Roller Chains

Number of teeth = 15

Number of teeth = 17

Number of teeth = 19

Number of teeth = 21