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).
Make ratio-speed curves for a 20 HP ignition contact breaker.
| Identifier | WestWitteringFiles\L\2April1924-June1924\ Scan108 | |
| Date | 5th April 1934 | |
| ORIGINAL To R.{Sir Henry Royce} from SFC. c. E.{Mr Elliott - Chief Engineer} DA.{Bernard Day - Chassis Design} c. GJ. & FW. c. EY. EP.{G. Eric Platford - Chief Quality Engineer} EPCL/T5.4.34. X.4357. UP-TO-DATE R.R. 20 HP. IGNITION CONTACT BREAKER. Attached please find copy of make ratio-speed curves for three different settings of the make ratio, viz., .45, .55, .65, at a speed of 700 R.P.M. (which is taken to be the normal speed), the corresponding primary gaps being respectively .026", .018" and .010". The middle curve corresponds to the standard production setting, which is for a .55 make ratio at 700 R.P.M. These curves are obtained utilising a non-inductive resistance in series with the contact breaker and battery, of such a value as to permit the passage of precisely 1 ampere, when the points are on contact. The reading of the instrument when the contact breaker is driven round at the various speeds is then a measure of the effective average make ratio, and the curves show the satisfactory manner in which the effective make ratio is maintained at the highest speeds to which the contact breaker is subject. EFC. Photostat attached. | ||