Page 1685 - MiSUMi 2025

Q Specification Selection for Operation under Normal Conditions 8. Chain Length and Distance between Shaft Centers
1.Operating Conditions Once the chain, the number of teeth on both
sprockets, and the inter-shaft distance are available,
When selecting roller chains, the following 7 determine the number of chain links as follows.
parameters should be taken into account. Lp: Chain Length Expressed
1. Machine to be used 5. Diameter and Rotary Speed of High-Speed Shaft Lp(No. of links) in Number of Links
2. Impact Type 6. Diameter and Rotary Speed of Low-Speed Shaft N1: Number of Large
Sprocket Teeth
3. Prime Motor Type 7. Inter-Shaft Distance N2: Number of Small
4. Power Transmission (kW) N 1 N2 Sprocket Teeth
Cp: Distance between Shaft
2. Application Coefficient Centers
Select the application coefficient from the application table (Table 1) that Cp(No.of links) Expressed in Number of
is appropriate for the machine to be driven and the prime motor type. Links
π: ≈3.14
3. Corrected Power Transmission (kW) (1) Calculating the chain length (when the number of sprocket teeth N1
Correct the power transmission (kW) using the application and N2 and the distance between shaft centers Cp are available)
coefficient.
• Single Chain…Corrected Power Transmission (kW)=Power N1＋N2 2
Transmission (kW)×Application Coefficient Lp＝ N1＋N2 ( )
2 Q
• Multiple Chains…Select the appropriate coefficient from the 2 ＋2Cp＋ Cp
table multiple-chain power transmission coefficients (Table 2). *Round up decimals of Lp to the next whole number.
Power Transmission (kW)×Application Coefficient
Corrected Power Transmission (kW)=
Multiple Row Coefficient Generally, when the chain length number of chain links obtained is an odd number,
this should be raised to the next even number. When the inter-shaft distance
4. Chain and Number of Sprocket Teeth demands the chain length to be an odd number, an offset link needs to be used.
Using the selection guide table (Table 3) or the power transmission However, it should be avoided and an even number should be used as much as
efficiency tables, select the chain and the number of small sprocket teeth possible by adjusting the number of sprocket teeth or the inter-shaft distance.
that satisfy the rotary speed of the high-speed shaft and the corrected
power transmission (kW). The chain pitch should be as small as possible, (2) Calculating the distance between shaft centers (when the number
as long as the required power transmission efficiency is achieved. of sprocket teeth N1,and N2 as the chain length Lp are available)
This should minimize noise and ensure smooth transmission of power.
1
8
(If a single chain does not provide the required power transmission Cp＝ 8 ｛ 2 Q 2 (N1－N2) 2
｝
2Lp－N1－N2＋ (2Lp－N1－N2) －
efficiency, use multiple chains instead. If the installation space requires
that the inter-shaft distance as well as the outer diameter of sprocket be The pitch number obtained by the chain length formula is, in most cases, only approximate
minimized, use small-pitch multiple chains). There should be a minimum and not in exact agreement with a given inter-shaft distance. Therefore, it will be necessary to
wrap angle of 120˚ between the small sprocket and the chain. calculate the exact distance between the shaft centers based on the required overall length.
5. Number of Large Sprocket Teeth
Number of Large Sprocket Teeth = Number of Small Sprocket Q Example of Selection for Operation under Normal Conditions
Teeth × Speed Ratio. Once the number of small sprocket teeth is The following is an example of selection when a 3.7 kW
determined, multiplying this by the speed ratio provides the number 1,000rpm electric (motor) is used to drive a compressor.
of large sprocket teeth. Generally, the appropriate number of small [1] Operating Conditions
sprocket teeth is 17 or greater, or 21 or greater for high-speed 1) Machine to be used ········ Compressor, 10 hours operation
operation, or 12 or greater for low speed operation. The number of 2) Impact Type ··········· Smooth Transmission
large sprocket teeth should be 120 or less.Select the sprocket with 3) Prime Motor Type ···· Electric Motor
as great a number of teeth as possible for a speed ratio of 1:1 or 2:1. 4) Power Transmission 3.7kW
The speed ratio should normally be 1:7 or less, and ideally 1:5. 5) Rotary Speed ········· 1,000rpm
6. Shaft Diameter [2] Application Coefficient
Ensure that the small sprocket selected as above is compatible with the diameter From Table 1, an application coefficient of 1.2 is selected.
of the existing shaft on which it is to be installed. Refer to the specification table [3] Corrected Power Transmission (kW)
on this page. When the shaft diameter is too large for the bore in the sprocket, Corrected Power Transmission (kW)＝Power Transmission (kW)×Application Coefficien
select another sprocket with a greater number of teeth or a larger chain. ＝3.7kW×1.2＝4.44kW
[4] Chain and Number of Sprocket Teeth
7. Inter-shaft Distance between Sprockets Searching the selection guide table (Table 3) for a
The distance between the shafts can be reduced as combination of 1,000rpm and 4.44kW provides a
long as the sprockets do not interfere with each other
and the wrap angle between the small sprocket and C-CHE40 chain and 17T sprocket.
the chain is 120˚ or more. On the power transmission efficiency table for the
Generally, the inter-shaft distance should preferably C-CHE40 chain, a combination of 13T and
be 30~50 times the pitch of the chain used. Under 1,000rpm provides a power transmission efficiency
pulsating load conditions, decrease the distance to 20 of 4.09 kW, which does not meet the required 4.44
times the chain pitch or less. kW. Therefore, 19T, which achieves 4.6 kW, should
be selected to meet the requirement.
Results:The C-CHE40 chain should be selected.
Number of Small Sprocket Teeth=19T
B-040