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).
Issue of oil entering Bentley dynamos from the tachometer drive and the potential sources of the problem.
| Identifier | ExFiles\Box 168a\3\ img398 | |
| Date | 9th June 1937 | |
| Rm{William Robotham - Chief Engineer}/Wst. BY.4/G.9.6.37. 6142 OIL ENTERING BENTLEY DYNAMOS FROM TACHOMETER DRIVE. -------------------------------------------------- Referring to Rm{William Robotham - Chief Engineer}/Wst.5/JH.4.6.37. I am certain that we have not done sufficient work on this to justify the removal of the air vent. In the first place when the oil level plug was added Mr. Maddocks immediately complained that he could not get cars off test because the commutator on the dynamo was being smothered with oil. As a result of the work which was done at this time in conjunction with your Department, it was made clear that without a vent the rise of temperature of the air in the little gearbox driving the tachometer forced oil through into the dynamo, and this action took place every time the engine cooled down and heated up, with the result that in a comparatively short space of time the dynamo was out of action as a result of oil on the commutator. We have referred your note to Mx.{John H Maddocks - Chief Proving Officer} who is emphatic that we shall be in trouble if we remove the air vent. In addition, the matter has been submitted to Mr. Bull of the Repair Department, whose remark is that trouble with oily commutators since the fitting of the breather is negligible. It is clear that there may be two sources of trouble:- (a). The original type with no oil level fixed by the position of the filling plug, as in this case either the gear fails completely, as it did in my own Bentley, although I added the amount of oil specified at regular intervals. or (b). If excessive oil is added complaints occur due to the commutator oiling up. In your tests although every facility was given to the commutator to oil up, the worst that occurred was a small amount of oil entering the dynamo end bracket, but apparently did not in any one case reach the commutator. I am pretty certain that if we delete the air vent | ||