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).
Technical memorandum discussing the design of an automotive exhaust system.
| Identifier | ExFiles\Box 14\6\ Scan057 | |
| Date | 30th January 1929 guessed | |
| contd :- -2- This suggests one expansion joint only at the front end of the main silencer, which in my scheme the silencer must be kept to its present length, or shorter. Cannot the front box half the vertical and all the horizontal pipe be made in one piece, or the expansion joint could be a special one on the horizontal pipe near the main silencer. Any internal pipes or nozzle, unless late in the system will get very hot, [struck-out text] as was found by the jacketed pipe, and expand and corrode, and perhaps ought to be made in some special alloy (staybrite) which has shewn to be good for heat and rusting. We bent the fishtail out sideways: this is a definite advantage of keeping exhaust fumes out of the car. My own experience here is that they are usually very bad in all cars, and I am inclined to believe that the reports of engine breather fumes were not from the engine crankchamber but from the exhaust pipe. However SS.{S. Smith} is better than most cars. From somewhere inside the frame as low down as possible try to arrange a horizontal sheet steel plate stay to control the front pipe or box in the two plan directions. Possibly we might gain a little mx{John H Maddocks - Chief Proving Officer} clearance etc. by being less particular about the brake ropes being parallel - i.e. those from the front countershaft to the front axle, but suppose these are limited by other obstructions. My object of these two breaks in the long length of exhaust pipe between the engine valves and cutout valve was not so much capacity but chamber of increased area to slow down the gas and destroy the kinetic energy and reduce the possibility of the air column rushing up and down this long pipe, as explained to Hs.{Lord Ernest Hives - Chair}, and in a previous memo. In the sliding joint one imagines that the unexposed part will always be the hotter, but certainly test your outer and inner scheme - three layers instead of two. I have generally suggested a long joint, a free fit, and circular grooves. I thought these very successfully. SEE ORIGINAL FOR SKETCH. They were very hot in the early part of the exhaust. Perhaps we ought to do the same on Mr. Elliott's part of the exhaust i.e. 3 leg. My suggestions should in no way limit your ideas: [struck-out: although] we must have the best. It looksas though a single bend might serve for the horizontal pipe, but my two bends would look better. SEE ORIGINAL FOR SKETCH. R.{Sir Henry Royce} | ||