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).
Tests conducted on a Borg & Beck clutch to determine the cause of lever bolt breakages.
| Identifier | ExFiles\Box 129\3\ scan0088 | |
| Date | 5th February 1936 | |
| X1110 P c. to By.{R.W. Bailey - Chief Engineer} c. to Da.{Bernard Day - Chassis Design} c. to Hdy.{William Hardy} c. to Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} FILE ONLY Tests on Borg & Beck Clutch to find reason for Lever Bolts Breaking. Tests Carried out on 3-B-IV - 11" Borg & Beck Clutch. The breaking of the finger lever bolts was suspected, from the fracture, to be due to fatigue due to a period. To prove this we have measured firstly the flutter of the flywheel and speed at which the flutter occurs. We then proved, both by washers fitted under the nuts of the lever bolts, and by measuring, that at a certain speed these levers had a period and were flung away from the face of the clutch case. To obtain the amount of movement, we first measured the amount of flutter of the flywheel, allowing for the end play of the crankshaft. By using a milli-ammeter in conjunction with a fixed contact, the slightest touch was registered. There was no sign of flywheel flutter until 4,400 revs. was reached. The sideway flutter registered was .028". Taking the radius at which the contact was made as 6.750", the amount of side flutter at the lever bolts with a radius of 3.625" would be .0151", assuming the line of flutter to be in a straight line from the centre. A contact was then fixed at this radius to measure the deflection of the bolts. We found that the period when the bolts left the case was between 3,700 and 3,800 r.p.m. We registered an outward movement of .032". Thus, taking the movement of the flywheel at this point, i.e., .0151", the bolts leave the clutch case during the period .0169". Above these revs. up to 4,500, there is no sign of the bolts moving. | ||