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).
Typed memo detailing an investigation into engine bearing and oil pressure issues on a demonstration car.
| Identifier | ExFiles\Box 146\1\ scan0107 | |
| Date | 17th February 1937 | |
| To Rm.{William Robotham - Chief Engineer} File 1240 Levallois Sr8/ET.17.II.37 Dear Rm.{William Robotham - Chief Engineer}, Just a few lines about the bearing situation as I see it at present. First of all, to put down on paper things we have spoken about on the telephone concerning my demonstration car B.35.KU, this is briefly the situation: When I first had this car out on the road, I covered about 300 Kms., covering about 150 of these at over 60 M.P.H. average. My oil pressure, as I told you, dropped to 12 or even at times 10 lbs. We investigated the matter and changed the oil pump and, on a run PB. gave to a customer over about 200 Kms., he reported the oil pressure to be 21 lbs. He did not, however, drive the car at much more than 4000 revs and was not heavily loaded. I again went out with the car on Sunday, the car being laden with 4 pretty hefty people, complete with plenty of guns and cartridges and shooting kit in general, again covering 300 Kms. approximately. On the outward run, my oil pressure dropped to 10 lbs. after about 48 Kms. on the road, and remained round about that figure for the remainder of the run. However, having covered 116 Kms. in 1 hour 1 minute and 43 seconds, we stopped for one minute and 40 seconds and went straight on to cover the remainder of the distance, roughly 47 Kms. During this distance, I drove the car to capacity i.e. between 4000 and 4500 revs, the road being slightly down grade and the wind favourable. My oil pressure, which up till the time we stopped had registered 10 to 13 lbs., now and during the remainder of the 47 Kms. in question registered 21 lbs. in spite of the fact that the engine revs were at least 300 more than on the first part of the trip. This is a mystery which I fail to understand. Upon dismantling the bottom half on the Monday morning, it was immediately obvious that the oil was pouring - no other expression will suffice - passed the crankshaft bearings. Having other work to do on this car, I decided to lift the engine out and investigate. The technical results, Allen has given you. We have now built up the engine again, correcting the clearances as much as possible and I feel fairly satisfied that the actual clearances must be over .003" and probably slightly more than .0035". As I mentioned on the telephone, we have changed two conn. rod bearings, which showed signs of having "reçu un coup de feu". | ||