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).
Bentley Pinion Thrust Race failures, cylinder head performance, and a note on the Vulture car.
| Identifier | ExFiles\Box 173\1\ img096 | |
| Date | 24th January 1934 | |
| To Rm{William Robotham - Chief Engineer}; from Hs{Lord Ernest Hives - Chair}/Gry.{Shadwell Grylls} Hs{Lord Ernest Hives - Chair}/Gry.{Shadwell Grylls}10/KW. 24.1.34. Bentley Pinion Thrust Race. We have had five failures of these now. I paid a visit to Ransome & Marles, who suggested as an immediate cure relieving the outside diameter of the half of the race further from the pinion. This half then takes the thrust and the other the journal load, instead of the one half taking both. In addition they have supplied us with a bearing of altered contact angle to give 30% increased rating. We should then be 2.6 times as well off. They have run a test of this bearing at twice our top gear full torque loads, which is 5 times the catalogue rating, and the bearing failed after 39 hours at 3000 r.p.m. They are now repeating this test on our Hoffmann bearing without relieving the race. Da.{Bernard Day - Chassis Design} has also issued N.Sch.3994 herewith, but Hs.{Lord Ernest Hives - Chair} prefers the R.{Sir Henry Royce} & M.{Mr Moon / Mr Moore} bearing as it exactly replaces the present one without upsetting the pinion setting. 4-B-IV starts 10,000 miles in England to test the race on Friday. Alum. Cylinder Head 7.35 C/R.{Sir Henry Royce} 1.450 Inlet Valve. This gives a good gain in power at middle speeds, but same at top speeds as larger inlet valve head and 6.85 C/R.{Sir Henry Royce} Pinking is very pronounced. SC. wants to make the bodies larger. Can we promise 130 HP. with 7.35 C/R.{Sir Henry Royce} 1.5 valves and good pistons ? We shall try and get this by enlarging the inlet valve on the new cast-iron head. Vulture. A real motor car - does Ticknall in 47 secs. and reaches 98 on the road quite quickly. Needs both hands to steer and the synchromesh 2nd speed works well. | ||