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).
Specifications and performance details for a contact breaker and secondary coil for a 20 HP chassis.
| Identifier | WestWitteringFiles\L\2April1924-June1924\ Scan143 | |
| Date | 1st April 1924 | |
| -2- Contd. CONTACT BREAKER: Normal speed (R.P.M.) (20 HP.chassis) 700 No. of breaks per revolution, 6 " " " " second. 70 Platinum gaps set at .022" for Test. .019 for Prod'n. Make ratio. r .50 for Test, .55 for Prod'n. SECONDARY. Number of turns. 18,000 Dia. of wire (inches)- .004" Approx. resistance (ohms). R' 4470 " inductance (henries) L' 35.0 8 Volts and a make ratio of the contact breaker of .5 is considered the working condition for test purposes. On production, however, it is instructed that the make ratio be initially .55, because the effective wear of the platinum points in the first instance would probably be a little greater than that of the rubbing block. Curves showing the behaviour of the make and break set to make ratios of .45, .55 and .65 at a normal speed of 700 R.P.M. were issued respectively under cover of and in our EFCl/T5.4.24. This mechanical performance is considered to be very satisfactory. The manner in which the make ratio varies with the primary platinum gap is shown on the accompanying photostat. At 8 volts and .5 make ratio, the running current at the normal speed (considered to be 700 R.P.M.) is .87 ampere. for 20 HP. chassis. Contd. | ||