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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).
Internal memorandum with sketches specifying the rounding of gear teeth for the Spectre Gearbox.

Identifier  ExFiles\Box 94\1\  scan0026
Date  25th August 1934
  
x6694 328

To RHe. from Hdy.{William Hardy}

C.c. Hs.{Lord Ernest Hives - Chair} By.{R.W. Bailey - Chief Engineer} Wr.

Hdy.{William Hardy}1/N.25.8.34.

GRY{Shadwell Grylls}

Re: SpectreCodename for Phantom III Gearbox.

With regard to the tooth rounding of the 1st. and reverse gears, will you kindly radius the sharp edges left by the machine, as we indicate on the sketches below.

We are anxious that only the minimum amount of radiusing necessary is provided in order that the loss of tooth face shall be the minimum, and for this reason we are starting with curves that may be somewhat on the flat side.

SECTIONS AT ROOT OF TEETH

REVERSE GEARS ON LAYSHAFT AND R SHAFT 20 AND 19 TEETH

1ST SPEED GEARS AND R PINION

.050 CHAMFER

.125

RADIUS BY HAND .050R AT ROOT OF TOOTH

DIMINISHING TO .025R AT TOP OF TOOTH.

REDUCTION OF EFFECTIVE TOOTH SURFACE NOT TO EXCEED .125

Hdy.{William Hardy}
  
  


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