Grand Piano simplex actions

[Clark]

Hi, Tony;

To mess things up, English escapement I think usually refers to
grasshopper jacks as opposed to French escapement which has tendered
jacks. English let (or set) off is tied to hammer height, where jack
position at rest is regulated by screw; French is like usual, where in a
single action often the jack is reversed (hammer height may be regulated
through a rocker arrangement). Furthermore, many actions employ a
combination of the two, where let off is forced through a sot of tangent
protrusion on the upright portion of the jack instead of a perpendicular
extension - these will have regulating screws through the hammer rail.

Double _escapement_, or just repetition action would be more appropriate
for instance in reference to Herz/Erard type actions: first the hammer
escapes from the jack, and when the key is raised from full depress it
escapes from check.

Anyhow, the Broadwood single has forced tangent let off. The Handy
Volume 11th.ed. Britannica shows a stiff cloth tab above the covered
knuckle to aid in reseating the jack, much as for Robert Wornum's, or
the French upright action (where the tape may perform a similar task: I
have a model for an 1830s Pleyel that has padding on the jack to prevent
wear in the tape). Brass rail with long pins, back check and under
dampers. Labelled from 1884, it is very nearly the same as the
preceeding illustration of a Backers type from 1776.

Also illustrated is Collard's grand action, which is a delightful
development to single actions. It has French escapement, although toward
the front of the key, and the jack bears a secondary check that works
upon the knuckle. Let off buttons are on pinned and sprung dollies to
minimize motion between the intersecting parts.

Repetition is possible with single actions, though, if indirectly and
not so reliably as for double actions - it can be accomplished through
incomplete key depresses, where let off isn't completed and the effect
is more like to a mop stick action (I think the tangent jacks in
Backers', Broadwood's et al. do this most successfully), or as the
hammer shank bounces off the rest rail there will be a narrow window for
the jack to reseat. The latter requires a certain amount of lost motion,
so at rest the jack should be set a little lower than the knuckle. At
least for American square single actions the hammer rest rail is just
that.

Hope this helps,


Clark