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).
Re-testing of dynamo and fan belts to identify the causes of failures.
| Identifier | ExFiles\Box 55\2\ Scan013 | |
| Date | 18th October 1912 | |
| R.R. 235a (150 H. {Arthur M. Hanbury - Head Complaints} ) (LL 57. 18.10.12) E.P. 2762. R9/B10213. XH h.W.Wormald C.J. from F.H.R. for Mr. Wormald. Re Test of Dynamo Belts & Fan Belts. There seems little excuse now for sending out any of these which are unreliable, at least we ought to be able to pick out the best. I suggest that the following comparisons should be made to find out the cause of failures. (1) Influence of speed, that is, tangential inertia, stretching the belt which would be worse with larger pulleys, a large belt is not necessarily better unless it will stand a greater load than in proportion to its increase of weight. (2) The influence of driving the dynamo( that is drawing the load) this would be better with larger pulleys & larger belts. (3) The influence of oils which are likely to get on the belt in use. It rather seems from our test that the ½ belt is no use under the conditions of our work and not one should be sent out which we can avoid. Mr. Leonard Williamson's car should be altered to ½ when we get the chance, we should get a reliable opinion of the value of the change. Many makes of belts can be compared. Our fan belt has to transmit much more power than the dynamo drive, but the larger pulleys seem to be an advantage, therefore, test the comparative values of different sized pulleys running the same speed and load, the most practical test is driving on the car lighting dynamos, charging a set of cells, driving from a little counter-shaft in the electrical department which should be fitted with a driving pulley the same as that fitted on the gear-box and belted up for two speeds say, 500 & 1500 or 400 & 1600 at the lower speed a good torque is needed to drive the dynamo and at high speeds the centrifugal force will stretch the belt until it will not drive at the lower speed. I think a good arrangement of a rig would be a small continuous current motor on a sliding bed fitted with two or three step pulleys driving a small fixed countershaft ( which is fitted with several sizes of both driving and driven pulleys) which, in its turn drives either a fan or a dynamo on a sliding bed by either large or small pulleys or high or low speeds. x1964 | ||