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).
Letter providing detailed specifications on pinion clearances, shaft materials, and clutch torque values.
| Identifier | ExFiles\Box 40\5\ Scan116 | |
| Date | 9th January 1923 guessed | |
| -2- Answering the questions in your letter of the 18th inst. in detail, we wish to give you the following information. 1. We recommend a clearance between the pinion bore and the shaft on which it slides of .005 inches. 2. We recommend that if a soft shaft is used, the pinion have a bronze bushing, but if the shaft is case-hardened, the pinion to be used without the bushing. It is our practice to use soft shafts with the separable type shift, with the bronze bushing, and case-hardened shafts with the integral type shift, without the bushing. 3. We are enclosing herewith our print B-10288A in duplicate, showing the chamfer of our pinion teeth. We would recommend that iron and unheat treated steel teeth be not chamfered. For hardened steel we recommend a chamfer of 45 degrees. 4. There is no adjustment for the torque which the clutch will carry. The mass and acceleration of the shift acting against the flywheel at rest, causes sufficient slip of the clutch to prevent damage to the teeth. As far as slippage at backfire is concerned, the maximum torque which our shifts hold is sufficient to protect the mechanism. These values are 20 ft. lbs. for the 2" shift, and 33 ft. lbs. for the 2 1/4" shift. These values, however, vary with the acceleration. 5. We are not familiar with any particular difficulties which should be given any particular attention. It would be wise to stock clutch discs, although they are capable of operating at least twenty thousand starts without replacing. We are enclosing a duplicate copy of this letter to be forwarded to Mr. Hives, as requested. Thanking you for your interest, we are, Yours very truly, (Signed) R.{Sir Henry Royce} P. Lansing Chief Engineer. RPL-K | ||