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).
Series of experiments modifying valve and damper components to resolve a 'squawk'.
| Identifier | ExFiles\Box 151\2\ scan0253 | |
| Date | 19th June 1934 | |
| -3- After that, valve modifications were abandoned, attention being next paid to the shape of the L.P. chamber. Normally the contour of the L.P. chamber is made irregular by the boss containing the transfer passage and the L.P. valve seat. The end of the valve chamber was filled with solder to the level of the boss, but again this had no effect. The possibility of the difference of restriction to the oil flow between the high and the low pressure passages after passing the valve was the next consideration, the original intention being to relieve any restriction due to the transfer passage. A pipe (5/16" dia.) was therefore attached from the vertical passage in the valve chamber to the H.P. end of the cylinder, thus creating an additional transfer passage, but this was not a success; possibly due to the limitations of the vertical passage. A similar experiment was performed by removing the H.P. refill ball valve, making the damper single acting, a pipe leading from the vertical transfer passage back into the reservoir conveying the oil thereto after it had passed the valve, instead of to the H.P. chamber. The L.P. "squawk" still persisted. Each refill ball was then removed in turn giving the damper first solely a L.P. action, and then a H.P. action. Under the former condition the damper was noisy, and under the latter, quiet. Then each refill valve was plugged up in turn, with just the same results. It was only possible to operate the damper for one stroke when both refills were blocked up, however, this showed the same tendency as the previous tests. Since it was not practicable with the standard damper design to increase the transfer passages by the desired amount, the reverse process was proceeded with, the aim being to balance the restrictions, by adding resistance to the L.P. flow. This was first accomplished by fitting "scrolls" inside the L.P. pressure chamber, and from these tests it was found possible to transfer the "squawk" from the L.P. to the H.P. stroke. | ||