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).
New specifications, testing issues, and quality control procedures for rubber engine mountings.
| Identifier | ExFiles\Box 65\4\ scan0118 | |
| Date | 7th December 1928 | |
| Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} C. Mx.{John H Maddocks - Chief Proving Officer} C. Wor.{Arthur Wormald - General Works Manager} c. Mr. Cox 48005 BY15/G.7.12.28. RUBBER ENGINE MOUNTING. We are arranging to instruct the rubbers in future to the scheme outlined in Hs{Lord Ernest Hives - Chair}/RmS/LG.4.12.28. i.e. we shall measure the load at a deflection of .150 instead of .100. This will mean that the loading of the rubbers will be slightly less by the new scheme than it has been under the old. With reference to the question of limits on the steel foot and its composite parts, we have reduced the limits in an attempt to eliminate variation, excepting the rubber itself. We wish to confirm our verbal remarks that we have never received rubbers in bulk which are anything like those specified. We are rejecting at the moment possibly 50%, and the variation on rubbers received under the load specified varies from 250 lbs. to 850 lbs. the difference in question being due to the characteristics of the rubber itself, the dimensions of the piece having been all brought to within 2/3 thous. of drawing dimensions before testing. We have confirmed that the rubbers you had received from the Works and tested, and which showed small variation were sent from Mr. Rich's Department and did not represent rubbers as received at the Works, but rubbers as passed for use in accordance with my instructions, and we think it is agreed that these rubbers were quite close to requirements. In future we propose not to use any rubbers which fall outside of the limits you specify. This means that we will avoid drilling rubbers through the core in order to bring them within the loading specified. This will increase the number of rubbers we are returning to the Dunlop Co. We also confirm that we have supplied you with rubbers from the last delivery showing very low poundages. The low poundage is the result of a complaint made against the previous delivery that they were all very high. Some of the recent deliveries were as low as 250 on the deflection whilst the previous delivery about which complaints were made and a large number returned went as high as 800 lbs. under the same deflection. Mr. Cox will in future not drill any rubbers, but will return all those falling outside of the new limits. | ||