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).
Significant oil pressure drop on chassis B.26.JD during high-speed testing.
| Identifier | ExFiles\Box 146\2\ scan0134 | |
| Date | 16th March 1937 | |
| Piles 1245 Swdl{Len H. Swindell} To Bentley Motors Ltd. Derby.................. Rm{William Robotham - Chief Engineer}/Swdl.{Len H. Swindell} Levallois Copy to ............................... Sr/VA7/ET.16.3.37 Re: CHASSIS B.26.JD{J. Draper - Frames} - Mr. Pierre-Louis DREYFUS With reference to our memo Sr/VAI/GM.3.2.37 (chassis B.107.GP. Mr. E.{Mr Elliott - Chief Engineer} DUBONNET), we did not remove the large capacity oil pump from chassis B.26.JD{J. Draper - Frames} and fit it to B.107.GP as suggested in our memo. We will fit one of the above type of pumps to B.107GP when we receive the first supplies of those which are on order. For your information, we have now carried out the final testing of chassis B.25.JD{J. Draper - Frames} and the chassis is very satisfactory with the exception of the oil pressure. We shall be glad if you will kindly refer to Sr.'s memo to you concerning the above customer, viz. Sr7/ET.2.12.36 addressed to Rm.{William Robotham - Chief Engineer} with a copy to Mx.{John H Maddocks - Chief Proving Officer} Will Mx.{John H Maddocks - Chief Proving Officer} also kindly refer to Sr.'s memo Sr.8/ET.2.12.36. Concerning the oil pressure, when the engine was started up, this showed normal maximum pressure. The car was then driven to the Trappes road, where we do our high speed testing. The above road, which is straight for a good 5 Kms., is about 30 Kms. from Paris. When the car arrived at the beginning of the Trappes road, the oil pressure was normal. The car was then driven full out once up and once down the above road. During the down run, which was the second one, the oil pressure dropped to 16 lbs. per sq. inch at 4000 r.p.m. and, when the engine was idling at 500 r.p.m., the oil pressure was 2 1/2 lbs. Upon referring to the last paragraph but one of your memo Rm{William Robotham - Chief Engineer}/Swdl.{Len H. Swindell}IO/JH.5.2.37, we find that you state you have always recovered lost oil pressure by fitting a large capacity oil pump to bring the pressure to normal, viz.30/35 lbs. We have never been able to obtain the above. You also mentioned in the same memo that the above chassis is fitted with a large capacity oil pump. Therefore in view of your remarks, we are surprised that the oil pressure should drop so low. We find that there are washers fitted under the relief valve spring and we therefore cannot fit any more, as the spring would be chock a block. We shall be glad if you will kindly let us have a reply by return as to what we should do in this case, so that the oil pressure remains between 30 and 35 lbs. per square inch when the car has been driven at high speeds for medium and long distances. We should mention that we are rather worried about the above. P.S. We attach to Rm{William Robotham - Chief Engineer}/Swdl.{Len H. Swindell}'s copy of this memo a copy of our Sr3/ET.I.2.37. Please refer to paragraph 9 Page I. Sr/VA [signature] | ||