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).
Technical memorandum discussing modifications to main casing bores, bushes, and valve components.
| Identifier | ExFiles\Box 99\3\ scan0055 | |
| Date | 19th January 1938 | |
| -2- HPS{Horace Percy Smith - Experimental Factory Mgr}/WB.{Mr Brazier/Mr Bell}1/EP.{G. Eric Platford - Chief Quality Engineer}19.1.38. If therefore, the desirable(from a manufacturing view point) common bores in the main casing are maintained, it will be advisable to safeguard against reversed bushes, to fit common bushes into each side and machine them in position. In this case it should be possible to final bore, face up to width, and ream the bushes at one setting. The alternative is of course, varying the bores in the casing, and consequently adopting bushes of different external diameters. No difficulty was experienced in pressing in the existing bushes, and the limits are considered suitable for production. [Handwritten note in left margin: ✓ (a) Delete flanges] It is necessary to clear away the bushes to permit the pistons to enter the cylinder bores, this involves a further machining operation with the existing arrangement, the alternative being to press the bushes into position with the clearance pre-machined, which is not desirable since it involves locating the bushes during pressing. Chamfering the bushes externally could be adopted, in which case no location during pressing would be necessary, and if it be proved that the consequently reduced thrust area be satisfactory, this method would be preferable. [Handwritten note in left margin: No bush spread centre] In this connection, it is worth noting that in a similar type of damper the bush flanges are deleted, the thrust being taken on the casing material, whilst simplifying machining, is not desirable where possible replacement has to be considered. The limit of the 1.000" diameter cartridge bore in the main casing could be increased to +.005" or +.010" without affecting the functioning of the damper, providing the top joint face is sound, thus reducing the fine limit bores in this section from three to two. [Handwritten note in left margin: Ⓡ] [Handwritten note in right margin: ✓] It is essential that the oil passages from the cylinder bores to the valve chamber be machined so that it is impossible for the pistons to mask them as is the case at present, unless a special overload valve be fitted. It is preferable that the oil passages intersect the cylinder walls slightly below, rather than above, the cylinder head face. [Handwritten note in left margin: ?] With the assembled valve cartridge in position the clearance between the cartridge and the bottom of the main casing bore is only .040" i.e. the thickness of the joint washer. This does not allow sufficient clearance to permit variation of the valve load adjusting washer. This can be rectified in several ways, the simplest being by an increased angle(or flat bottomed) drill. continued | ||