Pianotech

  • 1.  Different backcheck

    Posted 03-29-2019 11:54
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    My son was tuning today and ran across a Zeiler vertical.  He took this picture and asked if I had ever seen this style backcheck before.  Truthfully, I never have.  Would some of you Wizards of Smart have information about what this is, and what it does?  Appreciated.  We aren't doing repairs to the piano, by the way.

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    Ted Rohde
    Central Illinois
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  • 2.  RE: Different backcheck

    Registered Piano Technician
    Posted 03-29-2019 12:04
    Seems like the back check not only checks the hammer, but kicks the hammer toward the string on release, so that the back check functions like a grand repetition lever to allow the jack to reset more quickly. Seems clever and workable.

    Richard West





  • 3.  RE: Different backcheck

    Registered Piano Technician
    Posted 03-30-2019 08:16
    Ted, 

    This is is a variety of double-escapement action. There have been a number of different ones designed and patented over the years with varying degrees of success. The downside, in vertical pianos, is the added expense so it's seldom that even high-end verticals will utilize them. 

    I have a Mathushek from around 1890 that has a similar, though even simpler, design. I've worked with a couple of the Mathushek uprights with double-escapement actions in the past and they actually work pretty well. The only bad part about the current one is that someone with more ability with wire cutters than brains snipped the repetition springs at the top of the back checks so I've got to wind a new set. <heavy sigh>

    You might want want to also look at Darrell Fandrich's patent on a design they developed some years back for a double-escapement vertical action - https://patentimages.storage.googleapis.com/2d/30/2d/9f688dcbd9b4f7/WO2014011640A1.pdf 


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    Allan Gilreath, RPT
    Registered Piano Technician & President
    Allan Gilreath & Associates, Inc
    Calhoun, GA
    706-602-7667
    allan@allangilreath.com - www.allangilreath.com
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  • 4.  RE: Different backcheck

    Posted 03-30-2019 21:40
      |   view attached
    and the Langer bp jack system which i saw on an upright piano (not sure which make).
    difference with what Alan mentioned is that the metal spring is not attached to the jack top so it is not being loaded but rather uses gravity as the hammer assembly falls back, so no extra spring tension adding resistance

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    Petrus Janssen
    Peachtree City GA
    678-416-8055
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  • 5.  RE: Different backcheck

    Registered Piano Technician
    Posted 03-30-2019 15:52
    Interesting. I ran into a similar design on a 1889 Estey upright several years go. 



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    Geoff Sykes, RPT
    Los Angeles CA
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  • 6.  RE: Different backcheck

    Posted 03-31-2019 13:45
    Well, I've certainly learned a lot from you all, and I thank you for it!

    Ted

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    Ted Rohde
    Central Illinois
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