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).
Design and required modifications for a crankshaft damper and spring drive for the Bentley 80 and C.I. Conv. 8 models.
| Identifier | ExFiles\Box 124\1\ scan0038 | |
| Date | 11th March 1939 | |
| [Handwritten] WYMAN notice [Crossed out in red] Please note Rm{William Robotham - Chief Engineer} [Red signature] File 1044 BH/NS{Norman Scott} c. Rm.{William Robotham - Chief Engineer} [Redacted text] [Typed] DA.{Bernard Day - Chassis Design}2/G.11.3.39. BENTLEY 80 and C.I. CONV. 8. CRANKSHAFT DAMPER AND SPRING DRIVE. Please receive herewith :- E.CD.1246 Harmonic Crankshaft Damper and Spring Drive. B.80 and C.I. Conv. 8. The crankshaft damper is of the Buick type, with a flywheel inertia of 125 lbs.sq.in. and a spring rate of 250 lbs.ft. per degree of relative oscillation between crankshaft and flywheel. It is not proposed to include the friction damping washers for flywheel shown in Figure 1. for the time being, so that Figure II only, should be detailed regarding the damper. The spring drive, of course, is the same for both figures I and II. The spring drive and its damping is in principle the usual RR. practice, only with very much simplified manufacturing methods to reduce cost. The oscillation amplitude of the spring drive is only 1.4 degrees against our usual 5 degrees. The stops are formed by the driving springs becoming choc-a-bloc and rate of the springs is considerably higher than those on the Wraith lll spring drive owing to the smaller amplitude. The best amount of damping friction for the spring drive damper should be determined by experiment. It is quite likely that the amount of damping called for on the design will be excessive, but this can easily be reduced by fitting weaker damping springs. The front nose of the crankshaft is modified to suit the new damper, and the 2.750 diameter journal crankshaft recently instructed should include this revision. The wheelcase is also altered at the oil retaining nose. Will you please detail and instruct experimentally as soon as possible. DA.{Bernard Day - Chassis Design} | ||