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67. Maintaining Player Pianos

We now offer a full line of player piano repair
and restoration parts at our
Online Catalog.

I do not pretend that I can solve all your player piano problems.  The following is a short list of problems I thought you could solve yourself.  Beyond that, you need to call your tuner.  Players are somewhat complicated to work on, so don't go beyond what you can understand by reading these helps and your own common sense.

We now have completed digitally typesetting the 1917 edition of William Braid White's Piano Tuning and the Allied Arts. It has three chapters on player pianos which were omitted in subsequent editions. We make them available here.

Here is a list of problems in numbers 68 through 71:


unknownunknownGreen bullet 68. Varmints, Lubrication of Player Pianos

unknownunknownGreen bullet 69. Adjustment of Player Pianos

unknownunknownGreen bullet  70. Bellows repair in Player Pianos

unknownunknowngreen bullet  71. Get a stalled Player going again

                        green bullet       Player Principles and Diagnostics


Here are two more suggestions:


Drastic option:

Another option is to trash all of the player works, and use the piano as a regular piano only. Do this by taking out the "stack" and storing it in the garage. Don't throw it away. It is one of those neat pieces of junk you can keep, "Because some day we might want to restore it."

Be sure you don't trash any of the parts of the regular piano. Check the action diagram at the end of the book to see what not to touch.

Take the big bellows out of the bottom of the piano with its rubber tubing and rods and levers. Take out the two big flat pedals that operate the bellows. BUT, be sure to leave the regular piano pedals and the rods that run from the pedals to the sides of the box and up to the action.

If in doubt, go visit a friend who has a regular piano, and note the items you must NOT remove from yours. If, after you have stripped out the player piano, all you have left are is wires, you are in serious trouble. Start saving for a new piano.



If you have an electric vacuum operated player from long ago, and, if the thing stops dead and smells like something is burning, your motor is bad. Open the bottom, and you will see a motor that looks big enough to run the elevator in the iron works.

You need to replace this motor and its vacuum pump with the new version which is vastly smaller. Order the new pump from my Online Catalogue or from your piano tuner.

Once the vacuum pump is in hand, invite your electrician friend over to figure out where to interrupt the original wiring and wire in the new vacuum pump. Buy new big hoses at the auto parts store to run from the vacuum pump to the "stack," or use the one provided in the new pump kit. Pitch the old rubber.

I suggest you ask your electrician friend to add a "goof light" which will tell you when the motor is on so that it is not accidentally left on after someone plays it. The deluxe model of vacuum pump we sell has this light included.

From Piano Tuning and the Allied Arts 1917 edition by William Braid White . . .
              (This is the beginning of his player section) .

Previous Chapter                    Next Chapter                      WBW Book Contents


It is not my intention in the following chapters of this book to write an exhaustive treatise on pneumatics. Elsewhere I have subjected the piano player mechanism in its present condition to treatment of a technical sort at some length and to this other volume the reader is invited for a more complete survey of the facts surrounding the construction and operating principles of these mechanisms. In the present chapter, I have indeed endeavored to set forth simply and clearly the requisite facts; but in a more condensed fashion. To treat the subject-matter again in all completeness would be to write another volume beginning at this page; but this is unnecessary, for the reasons stated. At the same time, I feel it proper to say that the reader who wishes to be thoroughly acquainted with the player mechanism, and is not satisfied merely to know that which every tuner must anyhow know to-day about players, should study the subject systematically. (1)

Need of Instruction.

It is no secret that the arrival and rapid progress of the player piano have been most seriously disturbing to those members of the tuning profession whose views are already formed and their methods more or less settled; in short, to the older and more conservative tuners. It is safe to say that as late as the year 1896 very few tuners had ever given serious thought to the possibility of a mechanism for piano playing being developed at all; much less to the possibility of its becoming immensely important to the trade and a knowledge of it in some shape essential to success as a tuner. That this should ever happen would have been thought absurd; that it should happen within fifteen years would have been thought ludicrously impossible. Yet the impossible has become the possible, the ''could-not-be" has become the Is. The player piano is with us; most of us have been caught quite unprepared for it.

Scope of these chapters.

In the circumstances, seeing that already nearly one-half of the pianos made in the United States are player pianos and that the ordinary upright piano without player seems positively to be doomed, it is plain that one could not very well avoid writing some chapters on the player mechanism in a book like this. On the one hand, then, I have attempted to make sure that the information given here shall be always clear, accurate and intelligible; whilst on the other hand I have not failed to remember that the tuner whose interest in the player is confined to attaining such acquaintance with it as will enable him to make necessary small adjustments and trace the cause of apparent defects in its performance, will neither require nor desire a lengthy treatise. To be accurate and intelligible whilst being also very brief is not easy; but I hope that I have succeeded measurably well in carrying out this requirement.

In this and the two following chapters, then, I undertake to set forth briefly (1) the fundamental principles of pneumatic player mechanism (2) a general description of the modern player piano in its pneumatic aspect and (3) such instructions as experience shows to be most useful in the adjustment and repair of defects. The treatment is such that the reader will have no difficulty in following everything set down here.

The Mechanism.

The player mechanism, whether it be built right into the piano or placed in a cabinet detached therefrom, is self-contained and entirely independent of the piano. Usually to-day it is interiorly built, fitting into waste space within the case of the upright piano. It is also now fitted into grand pianos, but in its principal embodiment remains an addition to the ordinary upright, built within the case, but independent of and not interfering with the regular action, scale or sound-board. The player mechanism can be withdrawn from the piano case very readily and is in all respects separate from the musical instrument itself. The function of the player mechanism is to render musical compositions by playing upon the piano action, either through the keys or directly upon the abstracts or wippens thereof. The player mechanism runs on power furnished by bellows blown by the performer. Various means for expression are provided, controlled either automatically or at the will of the performer, the objects of which are to permit, as required, variation of speed, use of damper lift, loud and soft stroke of hammers, and division of melody from accompaniment parts. All these requisites are made possible by the use of simple auxiliary devices. The selection of notes for the performance of a composition is undertaken by the aid of a web of perforated paper, spooled on a core and called a “music-roll.”

Source of Power.

The power for operating the player mechanism is furnished by bellows operated by the feet of the performer through treadles. The operation of the bellows system is not at all hard to understand. In fact, the entire player mechanism works on a system so generally simple that, once its principle is grasped, the reader can reason out immediately the method of operation and the function of any part.

Pressure and Weight of Air.

The air of the atmosphere in which we move and which we breathe is invisible and virtually intangible. Yet it is just as much to be reckoned with as so much iron or wood. Its density is less than that of the other materials mentioned, but is measurable nevertheless. Scientific observation has proved that air, like all forms of what is called matter, has weight. A column of air one inch square and the height of the atmosphere has a weight of very nearly 14.75 pounds or 236 ounces; so that we may say that the air of the atmosphere exerts a pressure at its bottom (the surface of the earth), of about 14.75 pounds per square inch.


Air is a gas and all matter in a gaseous state has the property of expanding continuously to fill any space in which it may find itself. This expansive property together with the weight of air is the foundation of the operation of all pneumatic machines. The air normally fills at normal pressure all closed spaces capable of containing air. It is everywhere and always present at normal pressure, unnoticed and unconsidered, until by some artificial means it is either rarefied or condensed. Then work can be done by means of it. If a closed bag, which is normally filled with air according to the natural facts of the case, be shut off and closed so that no more air can get into it from the outside, and if then the bag be enlarged, without any more air being allowed to flow into it, the contained air will have to expand to fill up the enlarged space. In so expanding, the air is acted on like the rubber in a rubber band which is stretched. It becomes thinned out, so that any cubic inch of it now weighs less than a cubic inch of it weighed before it expanded. Hence the pressure exerted by any quantity of it is less after expansion than before. Hence, again, the atmosphere outside, which has retained its normal pressure of 14.75 pounds to the square inch, is able to exert an effective pressure on the outside walls of the bag, because the inside pressure is reduced owing to the expansion of the bag; and hence the balance between the outside and inside air is disturbed.


Figure 21. Essential parts of player mechanism, pneumatic open; (not to scale)

Disturbance of Balance.

The player mechanism operates entirely through this disturbance of balance as between the atmosphere and bodies of air contained within enclosed spaces. Look at Figures 21 and 22, which show the various parts of a player mechanism drawn out in the simplest possible way to show the operation of each part, but not drawn in proportion or according to any particular existing player. In fact the object of the drawings is to show only the operation of the principle.


Figure 22. Essential parts of player mechanism, pneumatic closed; (not to scale)

Simplest case of pneumatic mechanism.

At the bottom of the illustrations will be observed the bellows with two ''exhausters," operated by the foot pedals, and one ''equalizer." One of these exhausters is open and the other closed. But let us suppose that the player is in a state of rest with, therefore, both foot pedals untouched and both exhausters closed. The compression springs behind the exhausters hold them closed normally. Well, now, the exhausters being normally closed, the reader will observe that (1) the outside air can find its way into the ''pneumatic" through the channels and the top of the valve; (2) the long channel from tracker bar, over which the perforated paper moves to the valve pouch, will also contain any air that may have flowed into it when a perforation in the paper was registered with the tracker bar hole ; and (3) through the little ''vent," which is just a pin hole in a cap, the atmosphere flowing in from the tracker bar will also fill the reduced pressure chamber and therefore the entire bellows system, which is in connection with it. This is the normal or at rest condition.

Operation of Exhausters.

If now, the foot is placed on a pedal and one exhauster pushed open, see what happens. Assuming that the tracker bar channel is sealed by the paper for the moment, as when no note is being played, it will be seen that the operation of the exhauster simply means that the whole inside cubical content of the player is enlarged by the exhauster being opened; the player, in fact, being made larger inside by just the volume of the exhauster. True to its nature, therefore, the air in the various parts of the player expands equally to fill up this space. But the illustrations show that a flap or strip of leather covers the openings between the inner wall of the exhauster and the interior of the player. This strip, however, is pushed aside by the rush of normal-pressure air into the empty opened exhauster, which continues until the pressure on either side of the strip is equalized. Therefore a quantity of air filling the exhauster, but at lower than normal pressure, is now trapped in the exhauster, since it cannot get back through the door which it opened once and is now holding closed (the strip) ; for this door is held shut by a spring just strong enough to keep it against the pressure on the inside of the player, and further, is of course held by the pressure now in the exhauster. But, the exhauster being now all the way open, and the pedal all the way down, the heavy compression-spring outside tends to close the exhauster again. Besides, the foot-pressure is now naturally released for the return of the pedal. Therefore the exhauster begins to close and in closing squeezes the air inside it, which is trapped there and cannot get back inside the player, until it is enough compressed to force its way out through the outer strip or flap into the atmosphere, being forced out by the closing of the exhauster. Once squeezed out, the exhauster is shut, and anyhow no more air can get back in through the strip or flap which presses on the outside of the exhauster. Therefore we see that one opening and closing of the exhauster has withdrawn a definite quantity of air from the interior of the player and has expelled it into the atmosphere. Therefore a “partial vacuum,” as it is called, is set up inside the player; or, in other words, the pressure of all the air inside the player has been lowered.


This being the case, the atmospheric pressure on top of the valve holds it down firmly on its seat and shuts off the reduced pressure chamber from the outer air, whilst conversely the pneumatic is open to that air and therefore remains at rest.

Reduced-pressure Chamber.

Thus the situation when the pedals are being operated is as follows: Pressure of air is being constantly reduced, inside the player, in the reduced-pressure chamber, in the tracker bar channel (though on account of the smallness of the vent, to a smaller degree), in the trunk channel between bellows and pneumatic action and in the equalizer. Now suppose that a hole in the paper registers with the tracker bar hole :

Operation of Valve.

Immediately, the atmosphere, which has of course, been pressing against the paper, finds its way down against the reduced-pressure air, through the tracker channel and under the pouch, losing a little by the way through the vent. The pouch being larger than the top of the valve button, rises against the pressure on the button, and lifts the valve spindle with its buttons. At once, as may be seen, outside air connection with the pneumatic is shut off, whilst connection is simultaneously made between the pneumatic and the reduced pressure chamber. Hence the heavy normal air in the pneumatic ''falls" by its own weight into the reduced pressure chamber, reducing the pressure in the pneumatic. The atmosphere therefore presses against the moving wall of the pneumatic, closing the same and putting the piano action into operation.

When the perforation passes over and the paper again seals the tracker bar hole and channel, the normal air under the pouch and in the channel no longer is reinforced by supplies from the outside and in consequence (since the bellows are operated continuously and the reduced pressure chamber always therefore is in a state of partial vacuum, being never in contact with the open air except at times through the very small vent), this normal air in the channel “ falls” into the reduced pressure chamber as quickly as it can “'fall” in through the vent (air being elastic in all directions, can “'fall,” as I call it, up as well as down). Therefore, partial vacuum again exists in the channel and under the pouch, so that the valve stem is no longer held up with its buttons but again sinks down and is held down by the atmospheric pressure on its top button. Therefore again the pneumatic is shut off from the reduced pressure chamber and placed in contact with the atmosphere, so that it fills with air at normal pressure, and forthwith opens. This operation may be repeated over and over again, quite as rapidly as the piano action can operate, and in fact, even more rapidly; provided the necessary sequence of perforations is present on the paper roll. This is the operation of the player mechanism. But we have yet to speak of one important accessory; the equalizer.


The equalizer is a reversed exhauster. Normally it is held open by a spring. It is also, as will be seen, connected pneumatically with the remainder of the bellows system and with the upper action of the player. When the exhausters begin their work, the air in the equalizer expands along with the rest and part of it moves outward to the air, so that the pressure in the equalizer is also reduced. If the pressure is enough reduced to overcome the expansive power of the spring (which never exceeds 8 ounces per square inch of area on the moving wall of the equalizer and usually is much less, so that a displacement of about 3 per cent, of the contained air is enough to enable the atmosphere to balance the spring and neutralise it), then the equalizer starts to close. Whilst closing, it does no effective work, but is in fact a drag on the bellows. When, however, owing to an increase in the number of tracker bar holes open, or to slowing up of the pedaling, or increased speed of the motor, or to any other cause, the effectiveness of the exhausters is reduced for a time, the equalizer, forced by its spring, begins to open; and in opening becomes, of course, another exhauster, automatically displacing air from the player and holding it till the exhauster can take care of it and expel it. This is the function of the equalizer.

Of course, the reader is well aware that there are many variations on the simple system here described, but all depend on exactly the same principles, whether one or another kind of bellows be used, whether single or double valve system be adopted, and whether the most elaborate or the simplest expression devices be provided. In the next chapter, I discuss the general varieties of construction amongst the players usually met with.


The motor system is equally easy to understand. As will be seen by the illustration on the next page, the motor consists of small bellows called “ pneumatics,” mounted on a block which is perforated with one long tube running through it from the bellows, provided with ports called “suction ports” which penetrate to the outside of the remote surface of the frame. Each pneumatic is also provided with a port which runs between its interior and the outer surface of the same block. A slide valve slides over the pair of ports belonging to each pneumatic and is connected with a crank shaft by means of a connecting rod, the pneumatic itself being also connected to the crank shaft.

Operation of Motor.

Now, when the bellows are operating below and the suction port is in pneumatic connection therewith by means of the tempo lever which opens a gate situated in a suitable gate box, the air pressure in the suction tube is reduced. When, therefore a slide valve is in such a position that it covers both the suction port and the outer air port belonging to any pneumatic (see the illustration), the air in the pneumatic flows outwards into the suction port and thence into the channel and so to the bellows. This causes the outside air to press against the moving wall of the pneumatic and begin to close it. This closing moves the connecting rod and turns the crank shaft, which in turn brings the slide valve along till the suction port is closed and the outer air port exposed to the atmosphere, when the pneumatic again fills and opens, thus continuing the rotary motion of the shaft and completing it. When a number of pneumatics, usually four or five, are arranged around a crankshaft at suitable angles, a continuous rotary motion is given to the shaft and the motor develops enough power to turn the take up spool around which the paper roll winds.

Motor Governor.

The operation of the motor governor is equally easy to understand. As will be seen by the illustration on next page, air which travels from the motor passes into a sort of small equalizer, held open by a spring. In passing this, it goes through an opening which may be covered by a valve block, the movement of which depends upon the position of the moving wall of the auxiliary equalizer. The movement of this wall depends upon the power of its expansion spring. If this spring, for instance, is at such tension that it pulls back on the wall with a pull equal (say), to 3 ounces per square inch of the wall's surface, then the equalizer will close down as soon as the pressure inside is reduced enough to give the outside atmosphere more than 3 ounces effective pressure per square inch. In so closing it tends to shut off the travel of air through itself from motor to bellows and thus governs the motor so that no matter how hard or how gently one pumps, that is to say no matter how much or how little partial vacuum there is, the governor acts accordingly, closing or opening as required but always maintaining such an opening that increased velocity of air travel shall be balanced by smaller area of opening, or decreased speed by larger area, maintaining always the same pull on the motor and keeping its speed steady irrespective of the state of the pumping on the pedals.


To change speed, however, or to shut off entirely, the governor includes a tempo box containing (see illustration), two valves operated by slides over them. When the re-roll slide is closed, and the tempo closed also, no air can pass from motor further than to these slides, and so the motor stops. When the tempo slide is opened, air can pass through, and according to the area of the opening, as determined by position of the tempo lever and hence of the tempo valve slide, the motor runs slower or faster. The more air is displaced in a given time, the faster it runs; and this is governed by the size of the opening. Steadiness is governed by the motor governor and speed by the tempo valve.

The re-roll valve is used to run the motor very fast when re-rolling the paper at the conclusion of the piece. In most players it is independent of the governing pneumatic, though the illustration here, for the sake of simplicity, does not show such an arrangement.

Many other accessory devices are used in various players, but these I reserve for treatment in the next chapter, where I shall speak of the principal existing types of players and the peculiarities of each. In the same chapter also I shall touch on valve systems, accessories, individual peculiarities and so on, in just enough detail to enable the reader to recognize these when he meets them; and to understand their operation and duties.

Physical Facts.

In conclusion, I append the following summary of physical facts, which should be learned by heart and carried in the memory :

1. Air, like all matter in any state, possesses weight; that is, air is affected by the universal law of gravitation.

2. Air, therefore, exerts pressure at the surface of the earth.

3. This pressure is about 14.75 pounds per square inch at sea level, but being equal and uniform in all directions is normally not felt.

4. The normal pressure of the air cannot be used unless a body of air in which the pressure has been artificially reduced is placed in opposition to it. Then it can be used.

5. This principle of "disturbance of balance" is the foundation of the entire player system.

6. The player uses very low effective pressure. Whereas a perfect vacuum would mean that the outside air could exert its entire pressure of 14.75 pounds to the square inch on the moving parts, it is impossible to obtain working pressure on the moving parts higher than from 1 1/2 to 2 pounds per square inch. In other words, the degree of vacuum obtained inside the player does not exceed at the most 15 per cent, and is usually less than 10 per cent.

7. All air expands immediately when its container is enlarged or when part of it is withdrawn from its container without more coming in. This expansion reduces pressure, in proportion to its extent.

8.The player bellows operate by enlarging the containing space, causing the contained air to expand, then by means of suitable flap-valves expelling the displaced air on the closure of the bellows, and thus producing a state of reduced pressure inside the player; so that the outer air can operate against the moving parts thereof by pressure on their outer surfaces.

The above statement of principles applies perfectly to every possible arrangement of devices, parts or accessories found in any player mechanism made.

1 The book referred to is "The Player Piano Up-to-Date," published by Edward Lyman Bill, Inc., N. Y., 1914

Figure 24

Continue to Chapter 12 . . .



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Buy the book we sell please if you intend to restore a player piano. This is the book:

Player Piano Servicing and Rebuilding:
A Treatise on How Player Pianos Function,
and How to Get Them Back Into Top Playing Condition
by Arthur A. Reblitz
Paperback - 216 pages
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  On to task 68.