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).
Technical memorandum comparing the off-set on Bosch and Delco-Remy contact breaker pads.
| Identifier | ExFiles\Box 61b\1\ scan0009 | |
| Date | 17th January 1927 | |
| To R.{Sir Henry Royce} from E.{Mr Elliott - Chief Engineer} c. to BJ. EFC. Hs.{Lord Ernest Hives - Chair} BY.{R.W. Bailey - Chief Engineer} X4041 E1/M17.1.27. X4275 X4284 X4041 BOSCH AND DELCO REMY CONTACT BREAKERS. We have received and examined the above units, and what "hits one in the eye" about them is the considerable amount of off-set on the contact breaker pad relative to the cam in each case. We should estimate that there is a considerable [text strikethrough] difference between speed of make and speed of break. There is nothing to indicate the direction of rotation of the Remy, but from the condition of the H.T. wipe contacts it is certain to be clockwise. [Diagram 1: Bosch] Bosch. Annotation: 25º APPROX [Diagram 2: Delco-Remy] Delco-Remy. Annotation: 30º APPROX [Text associated with diagrams] Direction of pathway of pad centre causes pad to run at the break & to linger on the cam during the make. By holding a set square against the models a very rough estimate of the angular offset is 25º Bosch, and 30º Remy. These quantities can be more accurately determined at Derby. We should like to see an RR. contact breaker arm tested with the same amount of off-set. If the existing cam is used we should lose a little stroke, but not in proportion to the change of radius because the geometry results in some magnification of the cam lift. | ||