The Complete Guide to Chain

# 4.1.3 Drive Chain Selection (General Selection)

A suitable chain selection may be made according to the flow chart Figure 4.8. EXAMPLE: Select a transmission chain for the conditions shown in Figure 4.9.

Type of Application: Drive of Belt Conveyor
Source of Power: Electric Motor 7.5 kW
Drive Shaft: Diameter 66 mm. 50 rpm
Driven Shaft: Diameter 94 mm. 20 rpm
Center Distance of Shafts: 1,500 mm
Starting Frequency: 4 times/day
Type of Impact: Some Impact
Reducer Ratio: 1/30

• Step 1. Confirm the operating conditions.
• Step 2. Determine the service factor Ks as shown in Table 4.2. In this example, the service factor is Ks = 1.3.
• Step 3. Calculate the corrected design power kW = 1.3 3 7.5 = 9.75 kW.
• Step 4. Consult the selection table (Figure 4.10). For n = 50 rpm and corrected power = 9.75 kW, you should initially select RS140 chain and a 15-tooth drive sprocket. These are not the final selections. See manufacturer's catalog for additional information.
• Step 4a. Calculate the size of the driven sprocket. Number of teeth in driven sprocket = 15 3 (50/20) = 37.5. Therefore, select a 38-tooth driven sprocket.
• Step 4b. Confirm that the chain meets the power requirements. According to the power transmission tables in the catalog, an RS140 chain with a 15-tooth sprocket is capable of transmitting 11.3 kW. Because 11.3 kW is greater than the design power of 9.75 kW, it is acceptable.
• Step 5. Confirm that you can set a 15-tooth sprocket and a 38-tooth sprocket within the 1,500-mm center distance and still maintain clearance. The maximum hub bores of each sprocket are 89 and 110, respectively. Therefore, these may be used.
• Step 6. Calculate L, the number of chain pitches.

C = center distance ÷ chain pitch

C =  1,500 ÷ 44.45 = 33.746 (sprocket center distance, in pitches)

L = (N + N′) / 2 + 2C + ((NN′) / 6.28)2 / C = (38 + 15) / 2 + 2 × 33.746 + ((38 − 15) / 6.28)2 / 33.746