Modified Stock Gearing - Boston Gear

Engineering Information
Roller Chain Formulas
Horsepower
Horsepower equals 33,000 foot-pounds per minute, or
550 foot-pounds per second. In terms of chain working
load or pull (P) and speed:
Sprocket Speed
12 x RPM
RPM =
Number of Teeth x Pitch
P x S
HP =
33,000
RPM of Driven Sprocket =
Driver Teeth x Driver RPM
Driven Teeth
HP =
P x Number of Teeth x Pitch x RPM
396,000
RPM of Driver Sprocket =
Driven Teeth x Driven RPM
Driver Teeth
HP =
HP =
Torque (lb.-in.) x RPM
63,025
Torque (lb.-in.) x RPM
5,252
Centrifugal Pull or Tension
Pull or tension caused by chain weight and velocity:
Chain Weight per Foot x (FPM)
Centrifugal Pull =
2
115,900
G
Ratio
Teeth in Large Sprocket
Ratio = or
Teeth in Small Sprocket
Fast RPM
Slow RPM
Total Chain Tension
Total Chain Tension = Working Load + Centrifugal Pull
Chain Working Load
When horsepower input is known, calculate for chain
working load or pull (P):
Chain Bearing Pressure
Bearing Pressure
Working Load
(pounds per square inch) =
Bushing Length x Pin Dia.
P =
HP x 33,000
FPM
Torque
Torque =Sprocket Pitch Radius x Working Load
P =
HP x 396,000
Number of Teeth x Pitch x RPM
Torque (lb.-in.) =
HP x 63,025
RPM
Torque
P =
Sprocket Pitch Radius
Torque (lb.-ft.) =
HP x 5,252
RPM
Chain Speed
Speed (FPM) =
Pitch x Number of Teeth x RPM
12
Factory of Safety
Chain Ultimate Strength
FS=
Chain Working Load
P-1930-BG 04/10 Boston Gear 800-825-6544 249