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).
Piston ring comparison with increased cylinder lubrication to investigate cylinder bore wear.
| Identifier | ExFiles\Box 148\1\ scan0211 | |
| Date | 27th November 1939 | |
| 1256 To Jnr.{Charles L. Jenner} c. to Rm.{William Robotham - Chief Engineer} Rm{William Robotham - Chief Engineer}/CFC.11/JH.27.11.39. REPORT ON PISTON RING COMPARISON WITH INCREASED CYLINDER LUBRICATION. Cylinder bore wear being one of our outstanding problems, we decided to run a number of tests on a standard engine with maximum obtainable lubrication to the cylinder bores. The object of the tests was to obtain oil consumption figures using Hepworth and Grandage high pressure 'L' section rings and standard 'L' section 'Cellotin' rings the results showing us the advantage, if any, of using the high pressure rings with maximum cylinder lubrication. The engine used was B.II No.4. unit which is a standard 4¼ litre Bentley engine. As it was essential to have comparison oil consumption figures, the tests were run in two stages. First with normal main engine oil pressure of 36 lbs.sq.in. then with maximum permissable main oil pressure of 50 lbs.sq.in. It was also necessary to have some idea as to the amount of oil flung up the bores whilst running under the different conditions, therefore a check on the bearing oil flow was taken. To do this, the unit was rigged up to run 'dry sump' and the auxiliary oil feed pipe from the oil pump was fitted with two taps, one in the oil feed circuit the other in a branch pipe from which a flow was taken. The method of checking the flow to the bearings was as follows. A timed flow of two gallons was taken from the lower half outlet to the oil container underneath the engine. The main oil pressure was also noted. Then auxiliary oil feed tap was turned off at the same time turning on the outlet tap sufficient to give a main oil pressure equivalent to that registered when taking the total oil flow from the engine. This procedure made sure that the flow from the outlet pipe was equal to that which normally went to the engine auxiliaries. A timed flow of one gallon was then taken from the outlet pipe. Subtracting the auxiliary flow from the total flow in gallons per minute gave the oil flow from the bearings. | ||