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).
Examination and comparison of Bosch and Delco-Remy contact breakers, focusing on the angular off-set of the breaker pad.
| Identifier | ExFiles\Box 61b\4\ scan0110 | |
| 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} X4275 E1/M17.1.27. BOSCH AND DELCO REMY CONTACT BREAKERS. X4275 X4284 X8093 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 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. Direction of pathway of pad centre causes pad to run at the cam on the break & to linger on the cam during the make. 25º APPROX Bosch. 30º APPROX Delco-Remy. 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. | ||