Problems with Japanese copy of DB601 engine.

Discussion in 'Engines' started by davebender, Dec 11, 2011.

  1. davebender

    davebender Well-Known Member

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    The romance of engines - Takashi Suzuki - Google Books

    - Induction hardening of crankshaft caused inadequate surface hardness. Excessive wear after 100 hours.
    - Crankshaft shows precipitation of troostite, which indicates inadequate quenching.
    There is a picture of troostite precipitated on an Ha-40 crankshaft.

    I'll leave it to our engineers to explain what this stuff means. :)
     
  2. GregP

    GregP Well-Known Member

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    When you form steel, it does not really matter what the Rockwell hardness is. When you want a specific ttype of steel, it does.

    If you form a crankshaft and then decide to harden it, you must decide what Rockwell hardness to make it. Once it is a certain high hardness, it becomes brittle. Think of cobalt steel. Hard but brittle.

    If you quecnh the steel, it will lose a several Rockwell points, but the brittleness will diminish decidely. The Japanese crankshafts were not sufficiently quenched and developed a micro-mixture of Ferrite Cementite, making them brittle.

    It makes the crankshaft break under the strain. No power equals a descending aircraft.
     
  3. Shinpachi

    Shinpachi Well-Known Member

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    #3 Shinpachi, Dec 12, 2011
    Last edited: Dec 12, 2011
    I heard the Ha-40 crankshaft did not contain nickel.
     
  4. davebender

    davebender Well-Known Member

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    If you read further down there is a long winded discussion about bearing types. There is also a table which lists three main problem areas.

    - Excessive crankshaft wear.
    - Fuel injection problems. Why didn't they revert to a carburetor? IMO a good carburetor is better then a poor fuel injection system.
    - Lubrication system problems. Daimler-Benz had to leap this hurdle also for the DB605A engine.
     
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