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).
The investigation of a Low Inertia Damper, focusing on friction load and spring specifications.
Identifier | ExFiles\Box 82\1\ scan0213 | |
Date | 22th August 1933 | |
Hotel de France. Chateauroux. Indre. To Hs{Lord Ernest Hives - Chair}/Rm{William Robotham - Chief Engineer} From G.W.H. 22.8.33. I. B. IV. We have received your telegram: DODD LEAVING WITH PISTONS & THREE CONNECTING RODS TOMORROW MORNING TUESDAY - ROBOTHAM. We hope you have received the two pistons. We did not send the broken one, as there was no evidence of how the fracture started, whereas the two sent show it clearly. RE LOW INERTIA DAMPER We have had this dismantled. The condition of the Ferobestos Friction washers was excellent, also the friction faces of the wheels. The slipping load had dropped to 10 lbs. The half crankshaft period has been inconsistant. There have been days when there was no sign of it, other times one could detect it when using the gears, therfore as we have run 6000 miles and the conditions are so good, I was loathe to fit the cotton duck fabrics. There does not appear to be any reason why once the plates are polished that the load should not remain consistant. What we have found, points to the fact, that in the first place, the friction load obtained and given in the specification is misleading ie. 19 lbs at 17 1/2 rad. It is utterly impossible to obtain this load with the springs fitted correctly. I would say that springs required to obtain 19 lbs friction load would have to be 50% stronger. The reason they obtained the 19 lbs load temporarily, is, half the springs are choc-a-bloc. Washers .030" thick had been fitted under the springs. We have found that if half the springs are choc-a-bloc say by .004", slipping loads of 20 - 25 lbs are easily obtained which gives a false result, because as soon as the slightest wear has taken place, the load drops to 10 - 12 lbs. For instance take the results of our tests. We fitted Phantom springs, which are slightly stronger, to obtain more load. A smooth slipping load of 20 and 25 lbs 17 1/2 rad. was obtained. A check of the springs however found six out of the 18 just choc-a-bloc. These were reduced not more than .004", result slipping load 15 lbs 17 1/2 rad. Therefore much stronger springs are required if a load of 19 lbs is necessary. We are confident that having made sure we are not getting a false load, the springs are not choc-a-bloc, a more consistant result will be obtained and we hope that the result will be satisfactory so that Ferobestos washers can be used. | ||