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).
Effects on thread contact when adjusting for wear in a nut by reducing shims.
| Identifier | ExFiles\Box 20\2\ Scan120 | |
| Date | 22th November 1933 | |
| -2- AEC.5/BE22.11.33. With regard to the method of adjustment, it is understood from the scheme that the intention is to take up wear by reducing the thickness of shims between the two halves of the nut. We would point out, however, that whilst this means would serve to absorb any lost movement, it would also automatically reduce the effective area of threads by a further 50%, since the inner faces of the nut threads would be brought into contact with the worm at the expense of the outer faces, which would be separated by an amount equal to the total wear on both sides of the thread. Each end of the nut would therefore take the thrust in one direction only, as shewn below. [Handwritten under left diagram] ORIGINAL CONDITION BOTH SIDES OF THREAD IN CONTACT [Handwritten under right diagram] CONDITION AFTER REDUCING SHIMS. INNER THREAD FACES OF NUT. ONLY IN CONTACT It is to be expected that both the rate of wear and the tendency to stick would be adversely affected under such conditions. In any case, it is doubtful whether any form of adjustment would prove satisfactory with a nut of this description, since the localised nature of the beading would inevitably give rise to uneven wear on the worm. RHC.{R. H. Coverley - Production Engineer} [signature] | ||