Rolls Royce Single Stage Supercharger

Discussion in 'Engines' started by harold schneider, Jan 11, 2012.

  1. harold schneider

    harold schneider New Member

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    This is a short overhaul of the Rolls single-Stage Blower.
     
  2. jerryw

    jerryw Member

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    R-R Merlin SC.jpg

    Speaking of Rolls-Royce Merlin single-stage superchargers, above is a copy of a drawing from "Allied Aircraft Piston Engines of WWII" by Graham White.

    Can you spot the error??
     
  3. jerryw

    jerryw Member

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    Wow! Almost 250 views of this post and still no one can spot the BLOOPER!

    Where are the experts???
     
  4. Jugman

    Jugman Member

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    "Piston Ring Oil-Seal"
     
  5. herman1rg

    herman1rg Well-Known Member

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    Her Britannic Majesty?
     
  6. engguy

    engguy Member

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    #6 engguy, Feb 10, 2012
    Last edited: Feb 10, 2012
    A piston ring type oil seal, is just a nomenclature deal. Now they just call it a seal ring. Automatic transmissions have lots of them, as well as hook ring seals.
    Its not an overhaul, its a sectional drawing. Thats the blooper.
     
  7. tyrodtom

    tyrodtom Well-Known Member

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    You might call that part a oil seal, or even ring oil seal (as in o-ring), but never would you call it a piston ring oil seal.
     
  8. jerryw

    jerryw Member

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    THE ANSWER!!!

    The blooper is that the drawing and the caption DO NOT MATCH.

    The caption says that this is a drawing of a single-stage, two-speed supercharger for a Merlin XX

    In fact, the drawing is of a single-stage, one-speed supercharger for a Merlin Mk II or III

    The Merlin 2-speed supercharger is much more complicated than the 1-speed. There are selector forks running through the mechanism and there are two pinions on the impeller shaft, one for high speed and one for low.
     
  9. engguy

    engguy Member

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    No it is not an "O" ring seal. It is a piston ring type seal ring. So the nomenclature is pretty correct. An O ring is a rubberish type ring, a seal ring is metalish.
     
  10. dairwin

    dairwin Member

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    One can spot the occasional errors in the manuals. Some of the foreign language translations can be shocking.

    The diagram is applicable to most single speed Merlins (one speed?), including my Merlin VIII.
     
  11. MIflyer

    MIflyer Member

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    I have found that in WWII articles and popular drawings it is common for them to say that a supercharger is "two stage" in in reality it is simply two speed.
     
  12. dairwin

    dairwin Member

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    For the Merlin, there were three general types described as; single speed, two speed, and two stage.

    The single speed engines used a single supercharger stage with one drive ratio. The two speed engines used a single supercharger stage but had two ratios driving it; a moderate and full speed (MS for low altitude and FS for high altitude). The most powerful Merlins had two supercharger stages, with two ratios driving.
     
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