Hi all.  I would appreciate some advice from anyone who has experience
of a Triumphodist expression system.  It appears to be a fairly simple
affair on a British Kemble player with a straightforward standard
single valve action, and a split stack.

The controls are as follows: Two pallet valves underneath buttons on
the keyslip: one for soft bass, the other for soft treble.  The buttons
control the level of suction to the stack, rather than operating pneu-
matics connected to the half-blow rail.

Pretty normal except that upon depressing the buttons the intake chan-
nel is _sealed_ rather than opened.  Upon operation of these buttons
air is thus _excluded_ from the system rather than being admitted.
They are only effective when the Triumphodist lever is set to _off_.

Two tubes from the expression holes at the bass and treble ends of
the trackerbar are effective only when the Triumphodist lever is set
to _on_.

Concern no. 1.

I cannot reconcile the fact that the tracker bar apparently lets air
_in_ to operate the feature and the buttons do the opposite.  Have I
missed something?  Are there special rolls for Triumphodists that have
holes present to _suppress_ its operation, and the absence of holes
invokes it?

These four tubes are connected to a selection box, a small assembly
that directs the appropriate pair of input channels to two outlet tubes
connected to the main bellows.  The bellows has two control pneumatics
held under tension to regulate the overall level of suction to each
half of the stack.  Quite effective too.

Each tube feeds into a primary valve, which under normal conditions
is _on_ as air is being admitted when the Triumphodist lever is set
to _off_.  Thus the pouch is inflated and operates the primary valve,
allowing _suction_ to enter a channel routed to beneath a secondary
valve pouch.  This larger valve stays _off_, and in this way normal
suction is maintained, regulated only by the sprung pneumatics.
Okay so far?

When the button is pressed, air is very quickly exhausted from the
control tubes, and the primary pouch collapses, thus allowing the
primary valve to fall and seal on its inside seat.  The outside valve
facing now exposes the secondary valve channel to atmosphere, and air
enters beneath the large pouch and operates the secondary valve so that
suction to the stack is much reduced.  The amount by which it is
reduced depends upon the tension in the pneumatic springs.

Concern no. 2.

What are the factors to consider in regulating the primary valve?
When tested in isolation (i.e., all bellows pipes are taped off) the
valves operate perfectly.  When fully connected to the stack, however,
they are very sluggish, and sometimes will only work when both buttons
are pressed at the same time.

I guess this is a matter of trial and error.  I have used the normal
clearances and gap settings applicable to those in the valve chest.
Perhaps there are special considerations here that I have not taken
into account.

That's it.  I hope that I have not tired you all with my problem.
All advice welcomed and acknowledged.

Roger Waring
pianolas@dial.pipex.com