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).
Letter from Dennis Bros Ltd discussing engine performance, bearing tests, and seizure issues.
| Identifier | ExFiles\Box 116\1\ scan0057 | |
| Date | 1st September 1938 | |
| BY APPOINTMENT HEAD OFFICE AND WORKS DENNIS BROS LTD COMMERCIAL VEHICLE AND FIRE ENGINE MANUFACTURERS GUILDFORD SURREY. ENGLAND ALL COMMUNICATIONS TO BE ADDRESSED TO THE FIRM AND NOT INDIVIDUALS TELEGRAMS: DENNIS GUILDFORD TELEPHONE: GUILDFORD 1575 (7 LINES) OUR REF. JM{Mr Morley}/CS. YOUR REF. Rm{William Robotham - Chief Engineer}/Gry{Shadwell Grylls}/R.{Sir Henry Royce} DENNIS ESTABLISHED 1895 A B C CODE 5TH EDITION LIEBERS 5 LETTER BENTLEYS MARCONI 1st September, 1938. Files. Messrs. Rolls Royce Ltd., DERBY. Dear Sirs, Further to our letter of the 27th ult. in response to yours of the 25th, we have pleasure in forwarding you herewith two prints made from Torsiograph records taken on our 100 x 120 4-cylinder "C" type engine running under perfectly standard conditions at 2000 and 2600 r.p.m. These will give you some indication of the performance of the crankshaft, and we may say that with all other speeds, up to and including 3000 r.p.m., the records show that the torsional oscillations were negligible. In connection with our further tests on AC9 bearings, we presume that Messrs. Wellworthy have already advised you that we were unsuccessful in obtaining a satisfactory performance. Therefore, in view of the results which we have had with AC6 on our Diesel engine, we persuaded Messrs. Wellworthy to let us have one bearing in AC6. This was fitted on the 30th ult. At the end of 3 1/2-hours running, while still under part load at 2400 r.p.m., this bearing seized as per enclosed photograph. This bearing was set up with .0035 diametral clearance and an end clearance of .009. Mr. Blackith of Wellworthy happened to be in our Works at the time that the seizure took place, and he made a short examination of the bearing before he left. While dealing with this subject of bearings, it may be of interest to you to learn that we have recently had a few bearings made with lead bronze shells lined with a lead base white metal very similar to the bearings manufactured in Germany by Messrs. Braunschweiger Huttewerke of Braunschweig. Our tests so far, with engine speeds of 3000 r.p.m. with Triple Shell oil at 90°C, have proved satisfactory. Our tests are now being extended to 3250 r.p.m., with the same grade of oil at 100°C. Yours faithfully, DENNIS BROTHERS LIMITED. (Signature) P.S. In the case of the last test on AC9 material, the bearings were run six hours, no load, at 1000 r.p.m., followed by 4 1/2-hours (Left Margin Text) CUSTOMERS' VEHICLES DRIVEN AT OWNER'S RISK ONLY. | ||