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).
Tests conducted on a Bentley dynamo to determine the extent of oil leakage from the tachometer drive.
| Identifier | ExFiles\Box 168a\3\ img276 | |
| Date | 13th February 1936 | |
| To E.{Mr Elliott - Chief Engineer} c. to By.{R.W. Bailey - Chief Engineer} HS{Lord Ernest Hives - Chair}/Wst.1/JH.13.2.36. Leakage of Oil from Tachometer Drive. We have carried out your suggested tests on a Bentley dynamo to determine the extent of oil leakage, if any, from the tachometer drive on to the commutator. This consisted of running a tachometer drive for 100 hrs. A test was made using a large shunt dynamo of the standard Bentley type having the necessary gearing. The brushes, brush gear, and commutator were first cleaned; all dirt and oil being removed; and the brushes left free in their holders. The machine was then run for a total period of 100 hrs. at a speed of about 3,000 r.p.m. and output of 11 amperes. This output was decided upon, as being the right value for raising the temperature of the machine, to what it would most likely be, on the average on the car, i.e. 55° - 60°. During the run the gearing was oiled generously, but not flooded. After about six hours running, it was found that oil was leaking between the faces of the gearing housing and the adjacent end-cover locking plate. Further examination shewed a second leak between the faces of the locking plate, and the end-cover, on the bottom of which a small pool of oil ultimately collected. At the end of the first run, there was no definite evidence of oil having got through the bearing; that which got inside the cover having all come through the second leak referred to. The end-bracket and brush-holders were evenly covered with a film of oil, but the commutator, although blackened somewhat, appeared to be fairly dry. Generally the appearance suggested more the deposition of vaporised oil than "creppage". One brush was found to be definitely sticky in its holder, while a second was sluggish. It is clear therefore, that modifications are required to prevent this oil leakage. HS{Lord Ernest Hives - Chair}/Wst. | ||