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).
Preliminary tests of an Epicyclic gearbox with vacuum controlled twin top change gear on chassis No. 27-EX.
| Identifier | ExFiles\Box 6\2\ 02-page152 | |
| Date | 1st March 1931 | |
| To H.{Arthur M. Hanbury - Head Complaints} From Hs{Lord Ernest Hives - Chair}/Lid.{A. J. Lidsey} c. to SG.{Arthur F. Sidgreaves - MD} Nor. c. to E.{Mr Elliott - Chief Engineer} Da.{Bernard Day - Chassis Design} Hy.{Tom Haldenby - Plant Engineer} X523 Hs{Lord Ernest Hives - Chair}/Lid.{A. J. Lidsey}4/AT. 51. 3. 31. X7310 X523 EPICYCLIC EASY CHANGE GEARBOX. We have carried out some preliminary tests on the Epicyclic gearbox with vacuum controlled twin top change gear on chassis No. 27-EX. A very short first run showed that the vacuum controlled change was not working well. It would not change at all from third to top gear; in addition it was found impossible to get into two gears at once in the main (rear) box. The vacuum controlled change was made to work by - (1) Increasing the clearance between the piston and cylinder from .0015" to .005". (2) Removing the spring rings from behind the leather cup washers on the piston. (3) Making the sliding change speed Maybach dogs more free on the splines. (4) Adjusting the toggle mechanism correctly. In order to overcome the possibility of engaging two gears at once, the spring controlled Maybach dogs (in the main box) were done away with and replaced by an ordinary straight tooth dog of the type originally fitted to 14-EX when tests were made on constant mesh double helical gears for third speed. The second test immediately showed that the toggle spring load was excessive, producing excessive clicking of the dogs. The spring load was reduced by approximately 50% without interfering with the normal action of the dogs. General impressions of the behaviour of the gearbox are far from promising. (a) Noise. When idling in neutral (car stationary) the noise from the two pairs of helical gears is considerably more than one would wish for on a quiet car; there is little difference between the noise whether the Epicyclic is locked as in top gear, or revolving as in third gear; in the latter case the | ||