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).
Failures of the exhaust manifold, exhaust silencer, and fan during mileage tests.
| Identifier | ExFiles\Box 5a\3\ 03-page032 | |
| Date | 9th February 1921 | |
| -3- We have had a failure of the exhaust manifold, very similar to previous failures during 10,000 miles tests. We have endeavoured to find the cause of the failure and our theory is as follows. We are of the opinion that the failure is due to stresses set up in the manifold by the exhaust downtake pipe expansion effect. We carefully checked, after each 250 miles, exactly what was happening in the exhaust system, having made the sliding joint perfectly free. We noticed that a stress was being placed upon the stay holding the first bend of the downtake pipe. This stay is a piece of steel approx. 6" long, with one end attached to the frame, the other to the centre of the bend of the pipe. We replaced this stay by a thinner piece of material, and our theory was proved to be correct during the next 250 miles, the stay having buckled in the centre, but as the sliding joint was still functioning correctly, we continued running, observing after each trip any fresh result. Having satisfied ourselves that the exhaust system was working correctly with this scheme, we replaced the buckled stay by the original one. We found the manifold cracked after approx. 1,000 miles after the fitting of the strengthened stay. This result, we are of the opinion, verifies that the downtake pipe causes strains to be set up during the expansion period, and that the deletion of the stay, would most probably overcome these failures. The exhaust pipe is supported by a bracket from the frame further along the pipe in close proximity to the sliding joint. We are, however, continuing running with a thin stay, which has since buckled, but no further effects have been noticeable. We are anxious to prove this out owing to the number of failures we have been having with production cars. EXHAUST SILENCER. The lagging of the silencer is getting into a deplorable condition, the two halves gradually working apart over the ends of the silencer, the expansion of the steel bands allowing this to take place. The joint of the lagging at the bottom has gradually opened out, tearing away from the supporting steel bands. The extended Swanneck and other features of the silencer we have not experienced any trouble with. FAN to LOP.M.53250 - LeG.2921. To suit Engine Suspension with Dropped Radiator. It was noticed at a mileage of 7,500, a rattle had developed from the fan. The rivets holding two of the blades to the hub had stretched allowing the blades to rattle. It would appear that as the other blades did not show any sign of being loose, the rivets of the two blades mentioned, were not finally snapped up in the first instance. We have thoroughly riveted these blades up and shall note whether the looseness again occurs. The Dunlop Rubber Belt broke in two at a mileage of 8,500. The fracture of the belt gave one an impression | ||