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).
Report comparing Cadillac, Packard, and Chrysler gearbox and transmission systems.
| Identifier | ExFiles\Box 178\2\ img188 | |
| Date | 19th February 1934 | |
| -2- My one criticism of the Cadillac scheme is that, having avoided the extra wt. of the bell crank in the suspension proper, they still have to incorporate it in the shock absorber. I have been comparing the Packard 12, which is about as good as any conventional job I have tried, with knee action cars - Buick, Cadillac. The Buick is not as good as the Cadillac, chiefly through different shock damper setting, but both are better than the Packard, in the back seat particularly. GEARBOX. Weracher discussed the general outlook with me fairly thoroughly. He is a gearbox man of Chryslers, pioneer of the spool gear etc. CONVENTIONAL. They are completely sold on the sliding helical for a quiet bottom and reverse. They have had no trouble with it. They increase the unit loading on the splines (see female splines on the gear backed off) to overcome any tendency of the gear to move. I send you a drawing of the Chrysler box and also details of the helical sliding pinions. The box size will answer Hardy's question as to the centres used and the tooth loading. I asked Weracher what tooth proportions he would use if his sole object was to make a quiet light box. He said 45° helix angle 10 pitch. He does not like fine pitch carburised gears; he says the core becomes so small that the tooth strength is erratic. This sounds reasonable. The 10 pitch 45° helix almost exactly parallels what Packards are doing with such success. TRICK TRANSMISSIONS. Chryslers are about to standardise an overspeed epicyclic gear which fits onto the back of the gearbox. I enclose a surprisingly bad arrangement print. I shall try and call on the Warner people and get detail drawings. Its action is automatic. When the transmission reaches a pre-determined road speed, say 50 m.p.h., the engagement takes place automatically by a dog flying out and operating a Maybach type of clutch giving an overspeed of say 1.3. It was fitted to the Airflow Chrysler that I tried. I'm afraid that I cannot work up a great deal of enthusiasm for the device at present. | ||