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).
Component failures and improvements for springs, shafts, glands, and valves.
| Identifier | ExFiles\Box 119\1\ scan0127 | |
| Date | 23th August 1938 | |
| -3- RM{William Robotham - Chief Engineer}/AFM.{Anthony F. Martindale}1/JH.23.8.38. The springs have been unsatisfactory, there have been several failures. This is attributed to the use of inferior springs: correct supplies should be available shortly. The chamfer round the valve edge, and the washer between valve and spring, are an improvement and should be added to the drawing. The spring does not provide tight enough location for the valve, the centre of which has occasionally been riding on the hole in the piston. To give better location the flange of the piston should be increased in thickness: the present thickness of .025" is too thin and one piston has cracked through this piece. We have run phospher bronze springs a few hours and these were satisfactory. Knurled Shafts. (EXW.704) This cheapening scheme, is an excellent job and has run its 50 hours. The detail of the shafts will have to be modified slightly to suit the glands. It should ultimately go on to L.O.P. Glands - Duprone Rubber Rings. It proved impossible to assemble the shaft in the gland without cutting the latter very badly. Running the gland caused further disintegration and the oil was full of powdered rubber. Half the test was run without glands. It is always possible to revert to the former type of gland, but we are going to develop the present ones on a rig, trying various shaft forms and rubbers of various hardness. This would appears to be the most serious damper fault. Main Valve. The valve used was the small side valve drawn by By/Ald.{F. Allwood - Experimental Design} For 34 hours it ran with powdered rubber in the oil and seized repeatedly. This we eliminated by removing the glands. We have had three seizures since, using 'Thockol' low viscosity oil. On replacing this with Castrol F, no seizures occured but one valve became tight. The steel valve is runnin in a steel sleeve: we consider that if the sleeve were coppered or made of phosphor bronze (as on Wraith) that it would not seize. The clearances may have to be increased. | ||