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).
Performance and failure analysis of Gates Vulco and Dayton Cog V.C.17 belts under testing.
| Identifier | ExFiles\Box 135\1\ scan0241 | |
| Date | 8th November 1938 guessed | |
| - 2 - GATES VULCO. This was the first belt tested. It was during this test that the motor speed was seen to be steadily increasing as the motor warmed. The test was interrupted to allow the adjustment of the bush gear to correct this. After the initial adjustment of centres to bring the slip below 4% no further centre adjustment was necessary until 10 hours 27 minutes testing had been done. This point marked the first fan burst. During the interval between the bursting and the receipt of another fan, the vee belt, which had been removed from the test, was found to have decreased in length. This was noticed when the belt was retensioned prior to starting up with the new fan. The centres were as originally set at the commencement of the test and the slip was the same as before the fan burst. After 11 hours 45 minutes total running time, the slip suddenly rose to 6%. On stopping the test a blister was noticed on the outer periphery of the belt while the belt had the appearance of being stretched at this point. A fractured cord allowing the belt to stretch at the point of fracture was suggested as the reason for this. It will be noticed from the H.P. curve that the second fan did not have the same power absorption as the first. The appearance of the curve, the rapid climb to a maximum followed by sharp drop (due to stop, either mid-day, night or breakdown), followed by a similar rise will be noticed as a characteristic of all the curves herewith and is due to the aforementioned motor speed increase on warming up. The life of the fan used in the first part of the Gates Vulco test was not that given on the test report. This same fan was used during the initial running after the erection of the test gear and prior to the commencement of testing. This period may be taken as approx. 3 hours. DAYTON COG V.C.17. This is an open sided belt composed of what appear to be fabric laminations at the outer periphery, layers of whipcord at the vertical centre and solid rubber teeth on the inner periphery. The whole bonded by rubber with a layer of fabric, following the tooth form on the inner periphery. This belt stretched very rapidly and in the first 16 minutes of running it was necessary to increase the original centres by one inch. This brought it to the maximum adjustment possible, so that it was impossible to reduce the slip to the required limits during the rest of this test. At times the slip was as high as 6% and this gave rise to a periodic variation in fan speed. After 4 hours 21 minutes testing one fan blade sheared off and all the other blades showed fractures in various stages of development. This spider was rebladed and sent back to us for temporary use. After a further 2 hours 24 minutes testing this fan was returned to Rolls Royce on receipt of a third fan. This also marked the end of the testing of the Dayton Cog after a total of 6 hours 45 minutes unfinished. The belt is showing signs of deterioration. The cords on the surface are broken and pulling out in places, while the rubber at the base of the internal teeth is showing short radial cracks. - continued - | ||