High-tension or Low-tension?

[John Delacour]

At 22:04 25/09/01 +1000, Ron Overs wrote:


>>The instability with use, developing fast with heavy use, of the hopper's positioning under the notch owing to attrition of the cushion.
>
>John, curious to know what sort of grand action we are discussing here?

Brinsmead's latest patent action (probably 1886).  If you're not familiar with this, look at the Langer shop drawing illustrated in Pfeiffer's "Vom Hammer" Fig.42.  This is virtually a copy of an _earlier_ Brinsmead patent and lacks the extremely important later improvement to the escapement, but it illustrates the weakness I'm referring to.  Unlike the age-old English action (Stodart 1777, Petzold and so on) where the spring served only to return the jack under the notch, the spring here fulfils three functions, additionally providing repetition and lightening the down-bearing of the hammer.  Whereas the wear at the cushion would be tolerable in the older actions with the light spring, the great pressure of the spring in this action, acting against a small fraction of a necessarily softish cushion leads to rapid wear.  A hint of the solution to this problem seems to exist in Southwell's repetition action of 1837 but this is not clear and his solution would in any case not be friction-free.

Needless to say, the jurors at the exhibitions had new pianos to base their judgments on and Edgar Brinsmead in his Brinsmead-puffing History does not say what happens to their grand action after a year under the hands of a concert pianist.  However, there is a remarkably simple and elegant fix, which I won't go into at present.

JD