Lost Motion Compensator & Regulation

Joey Recker joey@onkeypianotuning.com
Thu, 16 Oct 2003 20:01:32 -0400


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As 'ol Arthur said on page 25.  "Lost Motion compensators were sometimes
used on the stickers.  In the regular verticl action, when the soft
pedal is depressed, pushing the hammer rail and hammers halfway toward
the strings, a space or lost motion is introduced between the jack and
the hammer butt.  The lost motion compensator makes use of the leverage
to eliminate lost motion when the hammer rail goes up, allowing the
pianist to play more softly by decreasing hammer travel distance, while
at the same time giving the keys control over the hammers through their
full stroke.  The compensator mechanism was used only on expensive
uprights made in the early 1900's, and it greatly enhanced the soft
playing capabilities of the upright piano.  Unfortunately, as
manufacturers sought to reduce their costs, this complicated device was
the first to go."
 
The one on my piano has joints in the sticker that rotate as the key is
pressed.  This joint his the lost motion compensator bar that runs
across the front of all the stickers.  This bar is connect by rods to
the hammer rail.  When the soft pedal is pressed the rail naturally
moves closer to the strings, and this raises the bar of the lost motion
compensator which moves the joints on the stickers, thus moving the jack
closer to the hammer butt as well as the hammers moving closer to the
strings.
 
Hard to put explain in print but maybe you can imagine what I'm trying
to say.
 
Joey
-----Original Message-----
From: Michael Gamble [mailto:michael@gambles.fsnet.co.uk] 
Sent: Tuesday, December 16, 2003 7:25 PM
To: joey@onkeypianotuning.com; Pianotech
Subject: Re: Lost Motion Compensator & Regulation



Hello Joey Recker
What's a "lost motion compensator"? Is it a dolly-top? a "touch screw"?
Any way is it a means of getting rid of the lost motion between the keys
and the action? If so, then (assuming the key dip is regulated and keys
are even) adjusting (or regulating) the "touch" is where you start. Then
follow ol' Arthur as you said.
Regards
Michael G (UK)


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