U.S. TSUBAKI BS/DIN ROLLER CHAIN
CHAIN DRIVE SELECTION
SELECTION PROCEDURE 1) The following factors must be considered when selecting roller chains for transmission needs. • The power to be transmitted. • The speed and the diameters of the driving shaft and the driven shaft. • The distance between the centers of the shafts. 2) Use Table I to obtain the service factor. (The “Service Factor” table refers to the type of machine and source of power.) 3) Multiply the HP value by the service factor to obtain the design HP value. 4) Use Table III page A-52 to obtain the appropriate chain number and the number of teeth for the small sprocket by referring to the number of revolutions of the high speed shaft (the driving shaft when the speed is reduced; the driven shaft when the speed is increased) and the design HP value. For a smoother chain drive, a smaller pitch chain is suggested. If a single strand chain does not satisfy the transmission requirements, use a multi-strand chain. If the distance between the shafts and the diameter of the sprockets must be relatively small due to space considerations, a multiple strand roller chain with a smaller pitch may be used.
Number of Pitches of Chain
5) After determining the number of teeth for the small sprockets, confirm if the sprocket will meet the shaft diameter requirements. 6) The number of teeth for the large sprocket is determined by multiplying the number of teeth for the small sprocket by the speed ratio. While it is preferable that the number of teeth for the small sprocket be greater than 15, it is suggested that the number of teeth for the large sprocket not exceed 120. By reducing the number of teeth for the small sprocket, the number of teeth for the large sprocket can also be reduced.
(
) 2
N 2 –N 1
N 1 +N 2
6.28
L=
+2C+
2 C Any fraction of L is counted as one pitch.
Center Distance in Pitches
{
1 8
C=
2L–N 1 –N 2
√
}
8 9.86
+ (2L–N 1 –N 2 ) 2 –
(N 2 –N 1 ) 2
L: Number of pitches of chain N 1 : Number of teeth (small sprocket) N 2 : Number of teeth (large sprocket) C: Center distance in pitches
Table II: Multiple-Strand Factor
Number of Roller Chain Strand
Multiple-Strand Factor
Chain Speed
Double Strand
1.7
P • N • n 12
S=
(ft./min.)
Triple Strand
2.5
S: Chain speed (ft./min.) P: Chain pitch (inch) N: Number of teeth of sprocket n: rpm of the sprocket
Chain Tension from HP
33,000 • HP S
T=
(lbs.)
T:
Chain tension (lbs.)
Table I: Service Factor
Source of Power
Internal Combustion Engine With hydraulic drive
Electric Motor or Turbine
Type of Impact
Machines
Without hydraulic drive
Belt conveyors with small load fluctuation, chain conveyors, centrifugal blowers, general textile machines, machines with small load fluctuation. Centrifugal compressors, marine engines, conveyors with some load fluctuation, automatic furnaces, dryers, pulverizers, general machine tools, compressors, general work machines, general paper mills.
1.0
1.0
1.2
Smooth
1.3
1.2
1.4
Some impact
Presses, construction or mining machines, vibration machines, oil well rigs, rubber mixers, general machines with reverse or impact load.
Large impact
1.5
1.4
1.7
A-51
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