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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).
Oil loss prevention and lubrication issues in the Spectre gearbox.

Identifier  ExFiles\Box 94\1\  scan0160
Date  18th July 1935
  
SECRET. 4328
To E.H.
Copy to Wor.{Arthur Wormald - General Works Manager} Hs.{Lord Ernest Hives - Chair} RMC. BY.{R.W. Bailey - Chief Engineer}
HDY.{William Hardy}2/MN.18.7.35.

SPECTRECodename for Phantom III GEARBOX.

With reference to the measures taken by G.W.H. to prevent the loss of oil by the middle compartment of the box as reported in GWH.{George W. Hancock - Head Chateauroux}2/JAB.12.7.35 and Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer}9/KW.16.7.35, we cannot see any objection to the plugging of the reverse shaft but the plugging of the hole in diaphragm for the trough may not be so satisfactory.

The trough was primarily provided (on P.2) to supply oil to the rear compartment when descending a hill with a box partly empty, in order to lubricate the servo worm.

In the SpectreCodename for Phantom III box the trough also feeds oil to the reverse shaft bearing and will do this when ascending a hill backwards with a partly empty box.

We do not understand why it is thought that the trough is not effective in reverse as the 3rd. speed gears which feed it run always in the same direction.

In view of the small size of the hole referred to (.5") and the relatively large return hole in the diaphragm (1.5") we do not think that the trough can influence the oil level very much.

We think that a guard to prevent the 2nd.speed cone throwing up oil (as suggested by Hs{Lord Ernest Hives - Chair}/FJH{Fred J. Hardy - Chief Dev. Engineer}) is likely to be the best way of dealing with the trouble as nothing that is practicable will prevent oil flowing to the rear compartment when the level in that compartment is lowered by the cone throwing the oil up in the box.

With regard to the holes in the layshaft for the supply of the 2nd. speed bushes, we have not provided these as in our opinion this source of oil would only be reliable when the box was full or nearly full of oil. By adding a trough to supply oil to the inside of the shaft we should ensure a supply so long as any oil was picked up by the 2nd. speed cone and this would appear to be a very satisfactory arrangement. Hs{Lord Ernest Hives - Chair}/Rm{William Robotham - Chief Engineer} suggests the use of a screw thread inside the shaft but it hardly seems to me to be necessary.

HDY.{William Hardy}
  
  


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