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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).
Distortion issues in Phantom gearbox gears due to spline hardening and proposing solutions.

Identifier  ExFiles\Box 94\2\  scan0110
Date  10th December 1936
  
To E.{Mr Elliott - Chief Engineer} & Hs.{Lord Ernest Hives - Chair} From RHC.{R. H. Coverley - Production Engineer}
c. to Da.{Bernard Day - Chassis Design}
c. to Hm.{Capt. W. Hallam - Head Repairs}
c. to H'dly.
c. to Hy.{Tom Haldenby - Plant Engineer}

GRY{Shadwell Grylls} 328

RHC.{R. H. Coverley - Production Engineer}11/MJ.10.12.36.

PHANTOM GEARBOXES.

Great difficulty is experienced in the production of gearbox gears owing to the fact of the locating splines being hardened. The distortion brought about by the heat treatment in some instances is considerable and such that it makes the gears impossible for use consequently the scrap for this reason is very high. The amount of distortion of course varies, some times a batch will go through quite satisfactorily, but it invariably happens that in the best condition only a portion of the effective spline area is used under operating conditions because of the distortion trouble.

It is therefore recommended that all gear splines should be left soft. This would enable the processing to be modified so that the final spline broaching operation is carried out before the grinding of gear teeth and will ensure that full advantage is taken of the effective spline area in final assembly.

This alteration would, apart from the economies which can be effected, remove many of the difficulties and be a step to improve the quality of gears, and would be satisfactory since the Brinell/is 360 to 380 and gears are being mounted on a hardened shaft. Whilst it is admitted that torque on these gears is greater than on other gearboxes the improved bedding that will be obtained should eliminate any wear on the splines, therefore steps are being taken to produce a number of gears to be tried out by Hm.{Capt. W. Hallam - Head Repairs} with a view to introducing them on Production.

In addition it is recommended that all Phantom 111 gearbox ball bearings should be of the 'Lapped' Type to improve the silence of bearings. According to reports received from Mx.{John H Maddocks - Chief Proving Officer} Gearboxes fitted with 'Lapped' Type Bearings N.1901 shewed a marked improvement compared with the Standard Bearings.

In the meantime we are trying to ascertain from the C.O. what the increase in costs will be but this is an example of where initial costs can be misleading and where far greater costs are incurred in the Factory due to the fact of changing finished gearboxes from Chassis and the dismantling of same which is necessary.

Therefore, actually if these steps are going to improve quality and remove some of the difficulties it will be an economy to pay a slight increase on the initial charges for the Ball Races in question. The Ball Bearings affected will be N.1901, 150, N.1993 (2 off), C.56227-N.1324, ES.12.

RHC.{R. H. Coverley - Production Engineer}
  
  


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