Sprocket and Roller Chain- A mechanical devised that are used in transmitting power from one shaft to another are parallel. It may be single or multi-strand.
General Recommendation in the Design of Chain Drives
1. The minimum number of teeth in a sprocket should 17 unless the drive is operating at a very low speed under 100 rpm.
2. The maximum speed ratio should be 7.0 although higher ratios are feasible. Two or more stages of reduction can be used to achieve higher ratio.
3. The center distance between the sprocket axes should be approximately 30 to 50 inches (30 to 50 times the pitch of the chain).
4. The arc of contact of the chain on the small sprocket should not be smaller than 120®.
5. The larger the sprocket should normally have no more than 120 teeth.
6. The preferred arrangement for a chain drive is with the center line of the sprocket horizon and with the tight side on top.
7. The chain length must be an internal multiple of the pitch and even number of pitches is recommended. The center distance should be made adjustment to accommodate to chain length and to take up tolerance and wear. Excessive sag on slack side should be avoided, especially on drive that are not horizontal.
Type of Sprocket
1. Type A is pain plate
2. Type B has hub on one side only
3. Type C a hub on both side
4. Type D a detachable hub
Type of Lubrication
1. Type I (Manual Lubrication)
2. Type II (Drip Lubrication)
3. Type III (Bath or Disc Lubrication)
4. Type IV (Oil Stream Lubrication)
Recommended SAE viscosities for various operating temperatures:
Temperature Viscosity
20-40°F SAE 20
40-100°F SAE 30
100-120°F SAE 40
120-140°F SAE 50
FORMULAS:
1. Pitch diameter of the small sprocket
D1= p / sin(180/N1)
Where:
P= pitch, mm or in.
N1= number of teeth of the small sprocket
D1= pitch diameter of the small sprocket, mm or in.
2. Pitch diameter of the large sprocket
D2= p / sin(180/N2)
Where:
P= pitch, mm or in.
N1= number of teeth of the small sprocket
D1= pitch diameter of the small sprocket, mm or in.
3. Outside diameter of the small sprocket
OD1= P (0.60+cot(180/N1))
Where:
P= pitch, mm or in.
N1= number of teeth of the small sprocket
OD1= outside diameter of the small sprocket, mm or in.
4. Outside diameter of the large sprocket
OD2= P (0.60+cot(180/N2))
Where:
P= pitch, mm or in.
N2= number of teeth of the large sprocket
OD2= outside diameter of the large sprocket, mm or in.
5. Length of the Chain
L= 2c + ((N1+N2)/2) + ((N2-N1)2/ 40c
Where:
c = center distance between sprockets
N1= number of teeth of the small sprocket
N2= number of teeth of the large sprocket
L= Length of the chain
6. Center Distance between sprockets
C= D1+D2
2
2
Where:
c = center distance between sprockets
D1 = center distance of small sprocket, mm or in.
D2 = center distance of large sprocket, mm or in.
7. Power Transmitted
P=2πTN
Where:
P= power transmitted, kw or hp
T= torque, N-m or lb-in.
N= linear speed, rpm or rps.
CHAIN AND SPROCKET application.
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