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).
Measurement and analysis of Ferogrip belt angles when bent to the radii of pulleys.
| Identifier | ExFiles\Box 135\4\ scan0081 | |
| Date | 13th June 1941 | |
| To:- Rm.{William Robotham - Chief Engineer} from Rm{William Robotham - Chief Engineer}/GB. c.c. EV.{Ivan Evernden - coachwork} Rm{William Robotham - Chief Engineer}/PJH. Rm{William Robotham - Chief Engineer}/Col. Rm{William Robotham - Chief Engineer}/HH. 1135- Rm{William Robotham - Chief Engineer}/GB.1/RH.{R. Hollingworth}13.6.41. We have measured the included angle for the .920" x .5" x 42° V.165 Ferogrip belt when bent to the radii of the useful range of pulleys. The method by which this was done is shown in the attached sketch. The belt rarely sat square on the surface plate so that after measuring the angle on one side, we turned it over and repeated the test on the opposite side of the same section. The measured angles (see attached graph) are the average of eight sets of readings on two belts. The calculated curve on the graph is based on two assumptions :- 1. that the area of any lamina in the belt remains unchanged whatever the belt radius. and 2. that the mould angle was 42°. It will be seen that when straightened, the theoretical belt angle goes up to 45½°. This appears to be so in practice. Ferodo recommended a pulley angle of 36° for the 5.65 dia. pulley and the measured angle was the same. The recommended angle for the 7" pulley was 38° and the measured angle was 38.3°. Ferodo's recommendations are based on intelligent guesses and what they have learned from the U.S.A. They have never measured belt angles. At their request, we are letting them know how we did it. Rm{William Robotham - Chief Engineer}/GB. | ||