Hi all.  Having just reassembled a restored Triumph Autopiano valve
chest and pneumatic stack and had it fail at the first major test,
I am somewhat taken aback.  Clearly I should have tested each valve
individually before full reassembly.  But how?  I would appreciate any
tricks of the trade from MMDers.  In the meantime, this is what I have
come up with for 36mm dia. valves with the pouch board off:

1.  Take the knurled metal nozzle from a tracker bar pump.  Front inside
diameter 37mm. Rear inside diameter 16.5 mm.

2.  Take a piece of straight rubber tubing outside diameter 16.5 mm.
Length approx. 110mm. Insert it into the nozzle so that it just
protrudes inside it. It must be an airtight fit in the nozzle.

3.  Take a wooden pencil or similar small thin shank approx. 125mm
long.  Put this inside the tube so that it just protrudes from the other
end.

4.  Take a piece of supple leather approx. 57 mm. square.  Cut a hole
in the middle 20 mm. diameter.

5.  Place the leather centrally over the seat of the installed valve to
be tested so that the valve parts and button are free to move.

6.  Place the nozzle and tube assembly over the leather so that it
exactly covers the valve seat.

7.  Press the nozzle head hard and "screw" it into the leather so that
there is an airtight seal at the valve board face. Hold it there.

8.  Put your mouth to the tube end and *suck*. The inside valve should
seal with no leakage.

9.  Whilst continuing to suck, push the pencil forward gently with the
tip of your tongue. (Good fun, eh?) This will trip the button and should
operate the pneumatic very smartly. If it is sluggish it will show now.
Any leakage in the outside valve (or indeed in the pneumatic) will make
itself heard.

10.  Whilst continuing to suck, release the pencil. The inside valve
should seal again and the pneumatic should close.

11.  Now regain your breath!

I do not suppose that this is even mildly original, and do not pretend
that it is in any way scientific, but it does allow you to become
intimately acquainted with actual valve operation and pneumatic
response.

I shall be interested to hear from anyone on the merits/demerits of
this method.

Yours breathlessly

Roger Waring