It is one of God's greatest gifts to mankind, for who is happy who does not serve? Hence it follows that service requires sacrifice. It is the foundation stone of every enterprise. Whatever it may be, its success or failure depends upon whole-hearted co-operation.
The functions of this unit are (a) to cut off the top action while the transmission is in the play position, (b) to silence any speaking note on the music roll that is passing over the tracker bar and (c) to increase the speed of the wind motor, causing that part of the music roll that is not desirable to pass quickly over the tracker bar. Therefore, this unit may be called the "silencer" or speeder unit.
This control valve is usually placed on the control slip near the "play and re-roll" lever, or it may be placed in the spool box on the bottom plate under the take-up spool. It is operated by means of a push button and a pallet valve and is, in some types of actions, controlled by the play and rewind lever when it is placed in the "silent" position.
In some types of pneumatic actions the wind motor may speed up under heavy pumping, but not under normal pumping (unless there is a broken connecting tube from the pallet valve to the silencer button). Should the motor speed up under heavy pumping look at the spring pallet valve under the key bed, remove the rubber tubing, and with a short piece of tubing connect to the pallet valve block, and test for leaks. There may be a small bit of dirt under the pallet, or the spring may be too weak to permit the pallet lip to cover the nipple snugly. To overcome this strengthen the spring.
Again, the rubber tubing may be broken at the brass nipple, or the brass nipple may be loose in the wooden block. In some types of actions the pallet valve is connected through a two or three-way wood block that has two or three channels in it. Leaks may develop in this two or three-way block through shrinkage of the wood, which allows a slow seepage of outside air to pass between the outer edges of the brass nipples; and while it is not noticeable under normal pumping it will be under heavy pumping. The remedy is a small amount of heavy shellac around the offending nipple.
In shellacking the nipples, care should be taken not to force the brass nipple too far in to the block, as it is apt to stop the channel and prevent the unit from acting, especially on re-roll, in certain types of actions.
The purpose of this unit is to raise the dampers away from the piano strings and to prolong or sustain the musical tone or tones. This unit may be a one, two or three-valved unit, depending en the design of the maker, and is controlled in two or three different manners; that is, (a) from the tracker port through the sustaining or loud pedal switch in the spool box, (b) by means of a lever on the control slip, or (c) by means of a push button-controlled pallet valve on the control slip. If other conditions are equal. this unit is rapid in action, and seldom gives any trouble.
Remember that the types of valves in this unit are the same as in the pneumatic action, and that they require the same remedies. Should this unit fail, under long usage, to function in the proper manner the valve or valves may become noisy in operation, which indicates too much valve motion. The remedy is the same as in the case of ordinary valves, that is, to build up the top seat of the valve with paper punchings. The levers connecting from the control slip should be free, with no binding or friction. By inspection, means will be found to regulate lost motion, although in the older types it may be necessary to build up on the arm of the pneumatic by means of felt or leather punchings.
The push button control that is located in the control slip has a pallet valve, and is "teed" into the tubing coming from the loud pedal switch in the spool box. Should it fail to act in the proper manner, it requires the same remedy that has been explained for the speeder or silencer pallet valve.
This unit is controlled through a tracker bar port on the right side, and its function is to raise the hammers upward to the strings in the grand type and forward in the upright. In some types of reproducing grands the action shifts, as when the left pedal is used on the piano, and may be used in combination, that is, to raise the hammers and shift the action at the same time, which give exceedingly fine shading to the reproduction of the music. Provision is made to take care of lost motion in the shifting or lifting mechanism, which is covered fully in the service manual of the action in question. Should the valve and the bleed fail to operate in the proper manner, keep in mind that it requires the same attention as any other valve. In a following article in this series the function and operation of the pedal governor, or pedal regulator, will be treated.
The divided hammer rail is controlled by levers on the control slip, marked "bass" and "treble". Or it may be of the button, pallet valve control type. Although, as a rule, the hammer rail is divided in two pans, as mentioned, in some types of actions the rail is divided in three parts, "bass", "treble" and "tenor".
In the button controlled type hammer rail division there is a pallet valve, connected to the lifting pneumatic, which pneumatic may be installed in the upper part of the piano and connected directly with the hammer rail. Or it may be placed underneath the key board and connected by means of metal rods to the hammer rail, and does not act until the button is depressed, admitting outside air to the valve. In the hammer rail which is divided in three parts the three ports on the control slip are always exposed to outside air, and do not act unless one of the ports is closed with the tip of the finger. In this type there is also provision for adjusting the travel of that portion of the rail that is raised toward the strings. These adjustments are treated in the service manual of the maker.
When the divided rail is controlled by levers on the control slip the levers should act freely without binding, lost motion or noise when coming back to rest after being released by the fingers. In the valve controlled type there are valves and bleeds which require the same care and remedies as ordinary valves.
This unit, which is known by several different names, namely, "bellows", "exhauster", "pump", and so forth, is used for the sole purpose of reducing the atmosphere within the pneumatic action and, in conjunction with a system of equalizers, to maintain reduced air pressure of the alternating pressure of the feet upon the foot pedals, and in every case is of sufficient size and of sufficiently sturdy construction to meet the most extreme demands on it, either of heavy or soft pumping. This unit will rarely give any trouble, even under adverse conditions.
Pallet valve trouble may develop in a player piano where a combination of foot pump and electric drive is used. That is, where the foot pump, or exhauster, has stood idle for considerable time the outside valves may become inoperative, on account of the valves sticking to the outer leaf of the exhaust pneumatic. The remedy is to remove the unit and slip a thin, flat steel, such as is used to slip under a loose bridge, under the outer edges of the leather valve and work around the edges so as to loosen it. Be careful not to force the small spring upward too much. If this is done the valve will not seat tightly.
It is an actual fact that the exhauster, or bellows, gives little, if any trouble under normal conditions, and will under actual test outwear two or three pneumatic stacks. It is a good plan when the unit is removed from the piano to inspect the exhaust springs, both the inside and outside springs. To inspect tie inside springs remove the small packed panel on the face of the bellows, or the exhauster. If the springs are found on the weak side they may be strengthened by grasping the points of the springs and bending outward, or they may be weakened by placing the blade of a heavy screw driver at the inside bend where the leaves are riveted and bending inward, starting from the bend upward and pressing in at an even pressure while working upward toward the tips of the springs. Feeder springs should be of equal strength in pairs, otherwise the foot "feel" will not be correct.
In the next article in this series I shall deal with electric motors before going into the electric expression players.
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