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 report on competitor flywheel, starter motor, and dynamo designs from American car manufacturers.
| Identifier | ExFiles\Box 173\2\ img194 | |
| Date | 7th March 1934 | |
| -3- I then found that they were getting 15-1 reduction on the Chevrolet flywheel and that it was done by reducing the tooth size. I thought it sufficiently important to cable you. This has been on Buicks and Chryslers for two years and seems to be the real secret on the job. I had no information of our tooth dimensions, so don't know how much we can get out of it. The pinion is 9 toothed, 1.1" overall dia., pitch dia. only .015" smaller than the O.D., i.e., practically no addendum, flywheel tooth to suit. Pinion made of Nickel Molybdenum S.A.E. 46.15 specification. When they want a lower gear than 15-1, as on the Cadillac, they put all the reduction in the motor and leave the old tooth size on the flywheel for strength. I send you a curve of the Chevrolet starter motor performance, with ours sketched in roughly from the figures available. They are supplying remote controls very extensively, the solenoid operation is widely used but is hard on the pinion. Accelerator starting is general, the engine vacuum holding the switch out while the engine is running. On Chevrolets the vacuum operates direct on the mechanical linkage. When the engine is dead, you can depress the accelerator only to the optimum throttle opening for starting. When the engine fires you relieve the pressure on the accelerator and the vacuum alters the linkage so the starter cannot be operated, but the accelerator can. It sounds involved, but Delcos like it from the point of view of increasing the pinion life and you should therefore examine a 1934 Chevrolet closely. (2) Dynamos. I particularly asked them about speeds, in view of our fears on the Bentley, and the fact that we are at present carrying about a large low speed dynamo which is heavy compared with the rest of the car. They said they had dynamos running that did 100 M.P.H. and the cars would do 80 M.P.H., which means 8,000 dynamo R.P.M. | ||