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).
Comparative analysis of quiet 1st speed gears for Junior Gearboxes, focusing on the Morris 8, Austin 8 and early B.V. models.
| Identifier | ExFiles\Box 136\2\ scan0334 | |
| Date | 30th June 1941 | |
| 1153 To Rm.{William Robotham - Chief Engineer} c. to Ev.{Ivan Evernden - coachwork} c. to Rm{William Robotham - Chief Engineer}/FJH.{Fred J. Hardy - Chief Dev. Engineer} c. to Rm{William Robotham - Chief Engineer}/GB. c. to Rm{William Robotham - Chief Engineer}/Wym.{G. Harold Whyman - Experimental Manager} c. to Rm{William Robotham - Chief Engineer}/HH. Ev{Ivan Evernden - coachwork}/Tln.5/JH.30.6.41. Quiet 1st. speed gears for Junior Gearbox. The Morris 8 gearbox has a quiet 1st. speed gear with straight teeth. To determine why it is quiet we have compared and contrasted the Morris 8, the Austin 8 (which is noisy) and the early B.V. with straight 1st. speed (which is noisy). The results so far are inconclusive. The reason for studying the Austin 8 gearbox is its general similarity to the Morris 8. The boxes are similar in general dimensions, arrangement of gears (with 1st. against the rear wall of the box), type of synchromesh, type of main bearings, overall 1st. speed ratio, DP. of 1st. speed teeth and appearance of tooth surface. These are the differences between the Morris 8 and Austin 8 gearboxes (with particular reference to 1st. speed):- (1) The Morris 8 box is cast iron, the Austin 8 aluminium. (2) The Morris 8 has an extended 3rd. motion shaft with a tail bearing. The Austin 8 has no extension, and presumably has a longer prop. shaft. (3) The Morris 8 teeth are less heavily loaded than the Austin 8. Unfortunately for this argument, the noisy boxes are noisy at low torques. (4) The Morris 8 teeth have a better contact ratio than the Austin 8, but noisy B.V. boxes have the best contact ratio of the three. (5) The Morris 8 teeth have less correction than the Austin 8, but B.V. is noisy with no correction at all. (6) The Morris 8 has a plain spigot bearing, the Austin 8 a Hyatt. (7) The Morris 8 has wider teeth than the Austin 8, but B.V. 1st. speed teeth are wider still. One conclusion that might be drawn from the above is that the quietness of the Morris box results from something we have not investigated. Perhaps gearbox mounting | ||