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).
Suitability of different starter motors and drives for the 'Japan 3' project.
| Identifier | WestWitteringFiles\V\March1931-September1931\ Scan007 | |
| Date | 3rd March 1931 | |
| ORIGINAL SECRET R.{Sir Henry Royce} FROM E.{Mr Elliott - Chief Engineer} C. to SG.{Arthur F. Sidgreaves - MD} WOR.{Arthur Wormald - General Works Manager} C. to HS.{Lord Ernest Hives - Chair} BY.{R.W. Bailey - Chief Engineer} EFG JAPAN 3. STARTER MOTOR & DRIVE. In our memo. E2/M5.2.31. we described the limitations imposed on the flywheel by the use of the Bijur starter pinion and mentioned the suggestion to use the sequence starter on Japan 3. According to DA.{Bernard Day - Chassis Design} the clutch can still be made suitable for the required increased torque within these limitations if desired. The present starting equipment however on the 20/25 is not suitable as it stands for use on Japan 3. The limited torque device has had to be fitted with a stronger spring to deal with the higher compression ratio of the latest 20/25s. and Derby are of the opinion that the motor itself is not large enough for use on Japan 3. The Bijur pinion is not greatly in favour from a production point of view. Also we want to replace the foot operated main switch by press button operation from the instrument board. There is one point that stands out we think in this problem, and that is the starter gear ratio should be considerably more than the present 20/25. This is especially desirable in a car intended for export to countries where extreme cold is likely to be encountered. Gear ratio of 20/25 is 8.4 to 1. " " P. 2. is 15.7 to 1. " " Delco-Remy is 20.5 to 1 (assuming flywheel of 20/25 dia.) The Delco-Remy has a plain spur reduction of 1.66 between motor and pinion engaging flywheel. It is operated by a foot pedal which slides a freewheel driven pinion into gear with the engine flywheel and then closes the main switch. A foot operated starter is not suitable for our purpose. There are already enough foot pedals with the foot switch for the lamps and the one for the central chassis lubrication. Everything points to the sequence starter. The only argument that can really be used against it is that it is more difficult to understand. If the connections are arranged so that it cannot be wrongly coupled up this does not matter. The only suitable alternatives in sight at the moment are the present motor driving a more powerful Bijur pinion through a reduction gear and operated by a relay main switch, or the sch. suggested in memo. R1/M21.1.29. in which the motor drives the engine through a slideable layshaft, the first motion gears being spiral and by their action causing engagement of the pinion with the flywheel, shock being absorbed by a spring loaded cork clutch in the driven gear. We should be very glad to have your views regarding this matter. E.{Mr Elliott - Chief Engineer} | ||