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).
Discovery and resolution of an incorrect spring thrust issue on the Bentley clutch.
| Identifier | ExFiles\Box 85\2\ scan0363 | |
| Date | 11th July 1938 | |
| fil 212 To BY.{R.W. Bailey - Chief Engineer} Rm{William Robotham - Chief Engineer}/NRC.{N. R. Chandler}3/B.11.7.38. RE: BENTLEY CLUTCH. Until recently we had no means of testing the actual total spring thrust of an assembled Borg & Beck clutch, as received from the Makers, but we now have a rig of our own design on which the effective working thrust, (quite apart from the individual spring poundage) is quickly and accurately measured. This will, in future, eliminate the risk of clutches with incorrect thrust going into production. The history of the change of spring is briefly as follows :- When Thermoid facings were first fitted to Experimental cars, late in 1937, we found a slight tendency for slip on making a quick get-away, and on investigation found the springs supplied with the clutch were slightly under their nominal poundage. We therefore called a conference with Borg & Beck and the suppliers of their springs, and decided upon a new spring to provide a slightly increased thrust. Borg & Beck had overlooked the fact that the new spring, having a considerably higher rate per inch, would produce a thrust in excess of its nominal increase of poundage. We discovered the reason for this, and pointed it out to Borg & Beck, who admitted they had overlooked the point, and agreed to change the springs of all the clutches supplied, free of charge. Rm{William Robotham - Chief Engineer}/NRC.{N. R. Chandler} | ||