From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Calculations for an E.A.C. starter motor's torque, speed, and power requirements.
| Identifier | WestWitteringFiles\K\June1923\ Scan73 | |
| Date | 19th June 1923 | |
| 19.6.23. X.9620 - E.A.C. STARTER MOTOR Overload engine torque assumed to be 1900 lb-inches. Speed reduction ratio = 30 Taking 85% gearing efficiency, effective torque ratio = .85 x 30 = 25.5 Overload motor torque therefore = 1900 ÷ 25.5 = 74.5 lb-inches. Engine speed assumed = 30 R.P.M. Motor speed = 900 R.P.M. Motor power is therefore .00001587 x 74.5 x 900 = 1.063 H.P. Assuming 53% efficiency at this power, electrical H.P. becomes 2.008 Motor watts = 1500 nearly. Motor volts = 8.44 Motor amperes= 178. (This allows 2 volts loss from 12.00 volts per 100 amperes). Contd. | ||