Yamaha U1

[pianoguru at cox.net]

The jack rail is effective in improving repetition..  Julia, you'll notice that in other upright actions there may be felt on the back side of the let-off rail to serve the same purpose, or a felt block on the jack near the top, or a smaller felt block on the back of the catcher, all serving the same purpose. The difference is that the rail is adjustable, to achieve the absolute minimum of necessary movement away from the hammer butt.  The same screw that mounts the rail is the adjusting screw.  If the threads of the screw were the same along its length, turning it would affect no change in the rail position, but the threads through the rail are "faster" threads than at the tip where it enters the main rail, allowing for the tiny bit of movement to finely control its adjustment.

Frank Emerson


---- Mark Wisner <markwisner at earthlink.net> wrote: 
> It's a jack-stop rail, and supposed to keep the jack from whipping too far on back on a very hard blow.
> 
> -----Original Message-----
> >From: KeyKat88 at aol.com
> >Sent: Aug 21, 2008 6:15 PM
> >To: pianotech at ptg.org
> >Subject: Yamaha U1 "extra" rail
> >
> >Greetings,
> > 
> >     What's with the extra rail in the front of the  Yamaha U1 action? I have 
> >never seen this before. Its down in front near the  letoff rail
> > 
> > 
> >Julia Gottshall
> >Reading, PA
> >
> >
> >
> >**************It's only a deal if it's where you want to go. Find your travel 
> >deal here.      
> >(http://information.travel.aol.com/deals?ncid=aoltrv00050000000047)
>