_Rr_, regulating rail. The _regulating b.u.t.ton_ is shown attached to the rail by the regulating screw which is turned by means of its ring on top of _Rr_. The purpose of the regulating b.u.t.ton is to throw the point of the jack out of the nose of the hammer b.u.t.t, and allow the hammer to rebound from the string. If the b.u.t.ton is too high, it does not throw or trip the jack in time to prevent blocking. When the b.u.t.ton is too low, it disengages too soon, and much of the force of the key is lost before it reaches the hammer.

_BR_, is the block rail, felted on the side next to the jack which strikes against it when thrown from nose. This rail is absent in some actions, in which case the back of the jack is felted and strikes against the "back catch," which is also felted on inner side. (The back catch has no mark in the cut, but is explained below in connection with the "back check.")

_BC_, is the back check which is simply a piece of wood with a thick piece of felt glued to the inner face and suspended on a wire.

_BCW_, back check wire supporting the back check, and screwed to the wippen. The purpose of the back check is to check the hammer by coming in contact with the "back catch" (the backward projection of the b.u.t.t), at a short distance from the string in its return, and prevent the hammer from falling entirely back to its rest position, thereby preventing quick repet.i.tion.

_Bl_, bridle. This is a piece of tape about an eighth of an inch wide with a piece of leather glued to the end and a hole near the end for the point of the "stirrup" or bridle wire. The cut shows where the bridle is fastened in the hammer b.u.t.t by being put into the hole in the b.u.t.t, and the back catch stem covered with glue and driven in by it which precludes all possibility of its coming loose. The bridle pa.s.ses through a hole in the lower part of the back catch. Its purpose is to a.s.sist the hammer to return quickly by hanging to it with the weight of the wippen, extension, jack, etc., when the key is released.

Thus the bridle becomes the main factor in the matter of quick repet.i.tion.

_Bl W_, bridle wire, screwed into wippen, bent in the shape of a buckle at top to hold bridle.

_Bt_, b.u.t.t; or, more specifically, hammer b.u.t.t. In some cheap actions the b.u.t.t is joined to its f.l.a.n.g.e _g_, by the means described under the head of wippen f.l.a.n.g.e; but in this action the center-pin is held firmly in the b.u.t.t by a small strip of bra.s.s containing a set screw; somewhat obscure in the cut, but discernible. As explained elsewhere, all center-pins turn in the f.l.a.n.g.e and not in the middle part.

_HS_, hammer shank in rest position.

_H_, hammer showing wood body or head, and covering of two layers of felt.

_H R_, hammer rail, resting on felt cushion, _c_, glued to rail or bracket. The hammer rail is held in position by the rod, shown under the hammer shank, which is hinged to the bracket at the lower end, and which allows it to be moved forward when the soft pedal is used. The soft pedal communicates with this rail by a rod which moves it forward and thereby shortens the stroke of the hammers and produces a softer tone.

_sr_, spring rail screwed to the brackets. This rail supports the light wire springs which a.s.sist the hammers in returning to rest position.

_S_, string.

_D_, is the damper head secured to the damper wire by a set screw.

_DL_, damper lever, working in damper f.l.a.n.g.e _g_, which is screwed to main rail.

_s_, spoon; so called from its shape. It is screwed into the wippen.

When the key is struck, the motion on the wippen throws the spoon forward, pushing the lower end of damper lever forward, and releasing the damper from its contact with the string. The damper is held against the string by the wire spring which is seen running from the damper f.l.a.n.g.e to the top of the damper lever.

_DR_, damper rod. This is a rod running from the left or ba.s.s end of the action to the right as far as the dampers are continued in the treble. It is acted upon by the "loud" or damper pedal, which raises the outer projection, and by being hinged to the main rail about the same height as this projection, the entire rod is thrown outward against the lower ends of the damper levers, releasing all the dampers simultaneously. This being the only office of the right pedal, it is readily seen that this pedal does not increase the loudness, but simply _sustains_ any number of tones struck successively, giving the effect of more volume.

The student should familiarize himself with all technical terms used in this lesson, as they will be referred to frequently in the succeeding lessons on repairing and regulating.

QUESTIONS ON LESSON III.

Without reference to anything but the cut, give technical names for parts of action represented by the following letters or abbreviations:

1. Bnc R, c, G P, BP, Ky, L.

2. Bm, Cpn, E, W, j, js, g, and M R.

3. Rr, B C, B R, B C W, Bl, and Bl W.

4. Bt, H, H S, H R, and sr.

5. S, D, D L, D R, s, B, and B B.

6. Explain the purpose and movements of the jack.

7. Describe a f.l.a.n.g.e and the joint of same.

8. Give names of the four f.l.a.n.g.es shown in cut.

9. What is the purpose of the back catch and back check?

10. Explain the mechanical action of the damper pedal, and its effect when used; also, that of the soft pedal.

LESSON IV.

~ACTION OF SQUARE AND GRAND PIANOS.~

ACTION OF THE SQUARE PIANO.

Up to about the year 1870, the square was the popular piano. The grand has always been too expensive for the great music-loving ma.s.ses, and previous to this time the upright had not been developed sufficiently to a.s.sert itself as a satisfactory instrument. The numerous objections to the square piano forced its manufacture to be discontinued a few years after the introduction of the improved new upright. Square pianos that come, at the present day, under the hand of the tuner, are usually at least fifteen years old, and more frequently twenty or more. However, in some localities the tuner will meet numbers of these pianos and he will find them a great source of revenue, as they are almost invariably in need of repair.

Compare the three cuts of actions in the study of this lesson.

The main const.i.tuent parts of the square action are similar in appearance to those of the upright; in fact, most of the parts are the same in name and office. However, the parts are necessarily a.s.sembled very differently. In the square action, the hammers strike in a vertical direction, while in the upright they strike in a horizontal direction; the motion of the key being the same in both.

Of the three types, the square is the simplest action, as many of the parts seen in the upright and grand are entirely absent in the square.

Beginning with the key, it has its balance pin, guide pin, cushions, etc., practically the same as in the other types.

The bottom, or key rocker, is reversed in the square; the end transmitting the motion being nearest the performer.

The extension and wippen are absent in the square, as the jack is attached directly to the bottom or key-rocker.

The back check is screwed to the key, and as the hammer head rests against it after striking, the use of the contrivance called the back catch in the upright is unnecessary.

[Ill.u.s.tration: ACTION OF THE SQUARE PIANO.]

ACTION OF THE SQUARE PIANO.

A. Action Frame.

B's Indicate the Cushions, or Bushing, of felt, cloth or leather.

C. Balance Rail.

D. Balance Pin. Round.

E. Mortised Cap for Balance Pin. Bushed.