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).
Sticking change speed lever, attributing the issue to incorrect shaft hardening and insufficient ball cage clearance.
| Identifier | ExFiles\Box 101\4\ scan0080 | |
| Date | 27th August 1935 | |
| x500a To Er. c. Hs{Lord Ernest Hives - Chair}/GWH.{George W. Hancock - Head Chateauroux} GRY{Shadwell Grylls} E.4/HP.27.8.35. Change Speed Lever Sticking - 21-G-IV. Referring to GWH{George W. Hancock - Head Chateauroux}/I/JAB.16.8.35, and GWH{George W. Hancock - Head Chateauroux}'s remarks with respect to the above, we understand that owing to the case hardening being ground off the shaft the surface on which the balls had to run was left soft, and this accounts for the balls cutting grooves in the shafts. There is, however, another point and that is the clearance of the ball cage with the shaft. In the case of the Bentley, which has been satisfactory, the clearance allowed between the cage GB.1753 and the shaft GB.1762 is dimensioned to allow 5 to 7½ thou. clearance. In the case of the 20-HP. the dimensions of the shaft E.57057 and the cage E.57030 allow from 1 to 3½ thou. clearance. The cage with the closer clearance is on 21-G-IV which has given trouble, and there is no doubt that this cage would soon pick up on the grooves made in the soft shaft. It would be advisable to give the 20-HP. the same clearance as the Bentley. E.{Mr Elliott - Chief Engineer} | ||