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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).
Engine gear whine tests performed on Bentley units B.7 and B.6.

Identifier  ExFiles\Box 136\1\  scan0104
Date  24th October 1933
  
To RHC.{R. H. Coverley - Production Engineer} From Hs{Lord Ernest Hives - Chair}/FJH.{Fred J. Hardy - Chief Dev. Engineer}
c. to E.{Mr Elliott - Chief Engineer}

ENGINE GEAR WHINE TESTS ON
BENTLEY UNITS B.7. AND B.6.

Attempts were made on Bentley units B.7. and B.6. to obtain quiet sets of engine gears without recourse to the usual production method of stoning and polishing the teeth by hand.

Great care was taken in machining the crankcases to ensure that the axes of the gears were parallel, similarly the shafts of the lapping rig were carefully lined up. The gears were produced by a method which eliminated casehardening distortion.

The first unit received was B.7. and the gears on this were bad when started up from cold. The steel gears were copper deposited and run to obtain a bedding. The bedding on all gears except the pump pinion was extremely good and could not be improved upon in any respect.

The bedding of the pump pinion was very bad as it was hard on the front of the pinion at one part of the circumference and hard upon the back of the pinion at a diametrically opposite part. The bedding is shewn on the attached sketch Fig.1.

The engine was rigged up so that it could be run with the pump pinion, idler, and dynamo pinion removed, together or separately. It was found that all the whine was due to the pump pinion as the gears were quiet with this removed.

The only errors that can cause the type of bedding shown in Fig.1. are as follows :-

(1) Axis of taper bore of pinion not parallel with axis about which teeth were cut and lapped.

(2) Axis of taper journal on pinion shaft not parallel with axis about which the shaft rotates.

(3) Bad eccentricity of inner race of ball bearing on front end of shaft.

The effect of any of the above errors is that the axis about which the pinion rotates is not parallel with
  
  


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