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).
Comparison of different starter motor engagement systems, including manual and automatic types.
| Identifier | ExFiles\Box 40\6\ Scan035 | |
| Date | 9th June 1922 guessed | |
| Oy2 - G 23522 Sheet #3 The great virtue of the manual shift is that since the engagement is made before the motor is moving fast, there is practically no shock and the flywheel teeth, even in C.I., last forever. The manual shift varies in detail. For example, on the single-unit Delco outfit the pinion is shifted into mesh positively by the foot and the current is sent to the motor windings by mechanically dropping the motor brushes on to the commutator. If the pinion teeth butt, relieving the foot pressure will make them slip in, since the armature is already being turned at a low speed through the "motoring" effect of the generator windings (like the old C.A.V. generator). On these systems, electrical contact is made after the pinion is engaged. On two-unit systems of any make the pinion is shifted through a spring, so that if the teeth butt the spring is set up under a good load before the starter switch is closed. With this provision and a good chamfer on the engaging teeth, the pinion slips home as soon as the motor starts turning. You will find that with any type of automatic engagement device (Bijur included) there are times, as when the engine makes a feeble start, when, because of reversals of engine torque, the pinion is dashing madly back and forth in and out of engagement. Also at other times, due to a stickiness or rust on the shaft, or a feeble battery, the motor fails to engage and whirls round with the pinion pressed against the flywheel teeth, and milling off the teeth like a regular machine job. Finally, consider that the four-cylinder Buick whose touring car sells for $950., uses the manual shift, Delco single-unit, and you will see what chance R-R have of getting away with a Bendix pinion on a car selling for say six times this figure. Enc. - 3 prints Oy. M.{Mr Moon / Mr Moore} Olley | ||