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).
Specifications for increased strength clutch and brake springs for an epicyclic 3rd speed gearbox.
| Identifier | ExFiles\Box 15\5\ Scan240 | |
| Date | 12th February 1932 | |
| HS.{Lord Ernest Hives - Chair} ) FROM DA.{Bernard Day - Chassis Design} BY.{R.W. Bailey - Chief Engineer} ) X7310 DAL/12.2.32. X.7310. COPY to - E.{Mr Elliott - Chief Engineer} EPICYCLIC 3rd. SPEED GEARBOX. Further to DAL/M29132., we have now looked into the question of the increased springs, and find that the clutch spring can be doubled in strength, namely, from a total load of 223 lbs. to 446 lbs., that is to say, 56 lbs. per spring, by using springs of the following particulars: .128 wire. 5 coils. Static load 56 lbs. Max: load 75 lbs. Static stress 50,000 lbs. per sq. in. Max: stress 67,000 lbs. per sq. in. Mean radius .375. As regards brake springs we suggest the following: Outer spring increased from 250lbs. to 349lbs. Wire .3 dia. 7 coils. Normal load 349 lbs. Max: load 405 lbs. Normal stress 70,000 lbs. per sq. in. Max: stress 79,000 lbs. per sq.in. Mean radius 1.062 Inner Spring 275 lbs. Wire .252 dia. 9 coils. Normal load 275 lbs. Max: load 331 lbs. Normal stress 68,700 lbs. per sq. in. Max: stress 83,400 lbs. per. sq. in. Mean radius .774. On again examining CL.521. we notice that the clearance for withdrawing the clutch appears to have been reduced compared with the original N. sch., by approx: a half, that is to say, from .1 to round about .050. This seems to us to be a mistake and suggest that it should be increased to at least .1 so as to make sure that the clutch comes clear. We cannot see any reason why this clearance has been reduced. If the particulars of the thread are as instructed on the N.sch. then a movement of .1 to free the brake is required. DA.{Bernard Day - Chassis Design} | ||