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).
The design and specifications of the Bentsport gearbox, including its servo, governor, and speedometer.
| Identifier | ExFiles\Box 179b\1\ img145 | |
| Date | 5th November 1932 | |
| DY.{F R Danby} ) FROM HDY.{William Hardy} HS.{Lord Ernest Hives - Chair} ) Copy to FA. BENTSPORT GEARBOX. HDY{William Hardy}/L/5.11.32 XU-53 We send herewith a print of N. sch. 3596 which shews the mounting of the rear end of the box, and the drives for the servo, damper governor and speedometer. This has not yet been thoroughly examined by R.{Sir Henry Royce} and consequently may be altered considerably later. The servo is not yet designed, and will no doubt need different brackets for the bridge than those shewn, which are the same as for Peregrine. We shew the Peregrine servo drive, and should like to know whether this drive is shewing any signs of being inadequate. With regard to the speedometer drive the axle ratio proposed with the J.{Mr Johnson W.M.} 1. engine is 11/41. We have provided bevel gears giving a speed up of 26/12. With a 1/8 servo shaft reduction and tyres of 28" effective dia. the revs. per mile of the speedometer are 730. This is sufficiently near our standard of 810 not to require any special features in the speedometer construction, such as larger magnets. There will be a slight loss of accuracy at the lowest speeds, but this is unimportant we think. The RPM. of the speedometer at the highest speeds will be greater than on our present cars. We have reduced the radius of curvature of the near side surface of the box to give more clearance for the 1st. speed wheel. This extends all the way along the box. The facing for the governor control unit is identical with that for Phantom, and the improved governor control which we are designing will be interchangeable on all cars. We think that in view of the use of the J.{Mr Johnson W.M.} 1. engine, and the recent failure on the Phantom box, the 3rd. motion shaft should be increased in strength. We will send the necessary alterations. Will you kindly say what is the amount of torque transmitted by the Phantom clutch such as HDY.{William Hardy} is on 18-EX. Is this adequate for future needs? If not by how much do you expect it will have to be increased. We require this information in order to determine the maximum torque that can be put on the transmission when the clutch is let in with the engine not synchronised. | ||