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).
Experiments on a servo mechanism, focusing on lining performance, area reduction, and cooling.
| Identifier | ExFiles\Box 2\7\ B002_X 140 to 143-page12 | |
| Date | 25th January 1933 guessed | |
| -2- improved until the linings were bedded in by running. It was found that after running from about 5 to 10 mins. with load varying from 0 - 150 lbs. intermittently, (max. about 30 lbs on pedal), all traces of grease or oil were removed and results as curve 3. obtained. Further running in and cooling right off gave results as in Curve 4. The effect of support of the end of the shaft by means of a jack was tried from time to time throughout these experiments, no appreciable difference being noted with jack in all positions, except when shaft was actually abnormally distorted by jack; in this case the output fell off. Experiments were then continued on Peregrine 4 servo. This was identical with the former (No.1) servo, except that the inner shaft was .050" less in dia. The linings were RAD.13. Curve 5. The first test did not give results equal to the best obtained with No.1 servo, but after scraping and running in as in case of No.1, the results were improved to Curve 5. As results improved on bedding in, it was decided to try the effect of a reduced lining area to imitate a lining with high spots. The area was reduced by 1/3 by drilling 20 holes evenly over the whole surface on either side of the mean radius. The result was a slight increase in output as in Curve 7. This shows that area of linings has no effect on output within limits. The fact that the consequent increase in unit pressure did not cause falling off of output was put down to the cooling effect of the air in the lining, and to the increased friction, produced by the leading edges of the holes. This latter was tested separately with a piece of the same kind of lining and the coefficient of friction was found to be slightly higher with holes than without. The effect of moving the cams into differe-nt positions, to alter anchorage point was tried, but no difference in results obtained. (See sketch 2.) With a view to allowing cooling air to get to the driving plate a .137" dia. holes were drilled through the outer lining plate and lining. This gave a slight | ||