Rebuilding Standard Action Valves
By Roger Waring
Denis Anderson and I are about to restore Triumph Autopiano players with what appear to be Standard valves. I have a few questions about these type of valves and would appreciate a little advice. Suction is poor when playing, and the stacks of both pianos appear to be leaky. I don't think it is all due to poor condition gaskets. We suspect that the problem may be with the valves but would like a more experienced view.
The valves that we have are a threaded thin wire stem type, 1.2" long, including the small cylindrical wooden button screwed on to the top. This button is .20" deep, .30" diameter, and is tipped with thin bushing cloth where it makes contact with the pouch. The two valve discs are of a reddish fibre, .70" diameter, .065" thick. The lower side of the bottom disc (the inside valve facing) is covered with brown (calf?) leather, suede faced, .05" thick.
The upper side of the top disc (the outside valve facing) is covered with white (sheepskin?) leather, suede faced, .07" thick. On top of this is a small, thin, brown leather punching, of smaller diameter than the hole in the dished metal plate into which the assembly seats when "on". The gap between the inside faces of the two fibre discs is approximately .06".
The whole assembly is held in place inside the valve chest by a rect- angular metal dished plate roughly 1" x 1.25", with four corner screw holes. Across one diagonal is positioned a narrow fibre guide, with a bushed centre hole to hold the wire in place. There is a similar guide attached at the other end on the outside of the valve chest. The plate is screwed to the chest with two screws only, and sealed with shellac.
Question 1. The leathers are generally OK on both instruments - a simple suck test using the metal seat is quite effective for both facings. Should we replace regardless? Is sheepskin OK?
Question 2. The small leather punching is not glued to the white suede. Should it be? What is its function?
Question 3. Many of the narrow fibre guides have their bushings missing, and thus the wire stem has a lot of play. Would this cause serious problems? Is too much play worse than not enough?
Thanks in anticipation; I promise not to hog the Digest with too many queries.
Roger Waring
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(Message sent Sun 23 Feb 1997, 00:14:45 GMT, from time zone GMT-0800.) |
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