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).
Fan belt tests, detailing the construction, performance, and failure analysis of a British Goodyear belt.
Identifier | ExFiles\Box 135\1\ scan0263 | |
Date | 14th December 1938 | |
14.12.38 JNL/MF. REPORT ON FAN BELT TESTS FOR ROLLS ROYCE LTD., ------------------------------------------ This report follows that dated November 8th 1938 on the same subject, and is concerned with two further belts i.e. British Goodyear manufacture, tested under exactly similar conditions. The belts were black covered, no name appearing, but marked in white ink N8620B. After collapse, belts were cut and examined. They were double covered, cord construction, black base rubber, grey tie gum. One belt had 10 cords the other 8 cords, the two missing being from one extreme side thus [DIAGRAM OF A TRAPEZOID WITH EIGHT CIRCLES] -> cords missing The report of November 8th is recirculated herewith with the table on page 6 enlarged to include these Goodyear belts results. BRITISH GOODYEAR N.8620B (No.1) Pulley diameter (base of vee) - 3-21/32")DAYTON COG. Pulley Angle - 33° -56')PULLEYS. Belt Periphery External start 49-15/16" finish 50-1/2" Internal start 46-5/16" finish - Initial Centres 16-3/4" Fan Speed 3950 - 4170 Driven Speed 4150 - 4490 % Slip Initial 4.6 Average 5.3 Maximum 9.6 Minimum 4.2 H.P. 19 - 20.5 Average HP (all test) 19.95 Average HP x hrs. run 41.6 Temp. of running 120°F Hours run 2 hours 5 minutes. Within 7 minutes of starting this test the centres were increased by 1/8" to 16-7/8". This brought the fan pedestal to the position where no more adjustment was possible. The test was continued at this setting for a further 23 minutes making 30 minutes in all, by which time the slip had risen to 6% and the vee belt was vibrating intermittently on the slack side. At this stage it was decided to remove one stud and re-position another on the bedplate to allow of more adjustment to the vee centres. The fan pedestal is now clamped by 2 studs only and overhangs the edge of the bedplate. The centres were then increased by 1/8" but this did not reduce the slip to below 4%. It was decided to run at this setting as the tension by this time was high. After 1 hour 15 mins. the centres were again increased as the belt showed signs of stretching, but again this did not reduce the slip to below 4%. Finally after 2 hours 5 mins. the slip rose to 9.6% and the test was stopped. In examination the belt showed a series of longitudinal grooves on the outer periphery. On cutting and removing the top cover, and exposing the cords, they were found to be fractured in 2 or 3 places and badly out of position, thus [DIAGRAM OF A TRAPEZOID WITH EIGHT CIRCLES] - 8 cords only. - continued - | ||