Wurlitzer Style 17 (Regular) PianOrchestra
Philipps Pianella Model Special
"Rocking-Arm" Valve Chest
with Attached 2-Tier Stack

(Photographs courtesy of David Ramey, Jr.)

Front view of the "rocking-arm" type valve chest and attached overhead 2-tier pneumatic stack. Lead tubing for musical notes and various control functions flow downward from the tracker bar and connected to a removable header at the bottom of the valve chest. Behind this header, and in the bottom board of the chest, are the inflatable pouches that lift the primary valves, the primary being located on the backside of the chest. The primaries control the much larger secondary valves, for which their individual atmospheric vents form a row of little rectangular holes across the chest's front cover. The group of four atmospheric vents right below the two sliding-valve register unit are for the valves that control the four little pneumatics that push the slider-valves one way or the other. The next valve to the right connects to the large lead tube going up alongside the register unit, which connects to a pneumatic that breaks the electrical contacts, turning off the electric motor.

(Photographs courtesy of David Ramey, Jr.)

Backside of the valve chest and attached 2-tier stack. Here the four primary valves for the register unit are visible at the far right, with all other primary valves for musical notes and other controls obscured by the pneumatic stack. The tubing sweeping up from the top of the stack goes to the pipe chest located directly above.

(Photographs courtesy of David Ramey, Jr.)

This detail image more clearly shows the primary valves for the two slider-valve register unit, which controls the piano soft pedal and the piano loud or sustaining pedal operation. The large pneumatic on top of the stack is connected by a wire to the piano sustaining pedal mechanism. Unlike most tracker layouts, which used a chain perforation for the sustaining pedal operation, the PianOrchestra scale used two perforations, an "on" perforation and a separate "off" or cancel perforation.

(Photographs courtesy of David Ramey, Jr.)

This partial front view of the stack (with the interconnecting trunk board and valve chest out of the way) shows the gasketed interface for each pneumatic tier. When in place, each tier will be screwed tightly to the trunk board extension attached to the top of the valve chest, ensuring an air tight seal between the trunk board and the drilled channels for each piano pneumatic. The support leg (one on each side) supports the outer, working end of the stack.

(Photographs courtesy of David Ramey, Jr.)

Detail view of the primary valves. Here the front cover over the lower vacuum chamber for the primary valves has been removed. The bottom leather valve seat is glued to the flat topside of a circular metal weight or button. This relatively heavy button keeps the valve in a downward position. Between the two valve seats is a drilled channel (not visible) that connects to the secondary valve's pouch. When the primary is at rest—no tracker bar signal—a vacuum is applied to the secondary pouch, but when the primary is lifted, the secondary pouch channel is vented to atmospheric pressure. This causes the secondary pouch to inflate (because it is in a vacuum chamber) and push on a rod that operates the secondary "rocking-arm" valve. A characteristic of the "rocking-arm" type of chest is the unusual primary valve design, with a stem guide rail situated high above the actual valve surfaces.

(Photographs courtesy of David Ramey, Jr.)

Pouches for the primary valves. Here the lifting lever in one pouch is shown elevated at its free end. The lifting lever for these pouches is more or less fixed in place at one end, which tends to powerfully move the valve upwards with very little pressure differential within the pouch. The fixed end of each lifting lever is not only glued to the pouch, but it is further held in place by a strip of leather. The leather strip has been peeled back for this photograph, but this restraining strip of leather is still in place for the pouches toward the top of the photograph.

(Photographs courtesy of David Ramey, Jr.)

Detail view of the secondary "rocking-arm" valves. Each valve pivots on its own little flange, which is glued to the inside wall of its valve chamber. Here only one "rocking-arm" valve remains glued in place—the others have been removed for restoration. Each valve has its own little exclusive chamber, and as should be obvious the complexity of building such a chest requires more care and exactness than does the more conventional chest with cylindrical, quickly bored valve chambers that employ simple wire stem valves and stamped metal valve seats. The "rocking-arm" valve has an inner fixed leather seat that seals off the valve chamber from the vacuum source, which requires that the flange must be of a precise height and also glued to the inner chest wall carefully, to ensure proper alignment of the fixed valve surface. If you were to lay a ruler on the valve surface the ruler should just barely touch the bottom of the flange. There is little room for error here. In contrast, the outer atmospheric leather seat is glued to an rectangular piece of fiber, which is then twisted onto a threaded wire projecting out of the rocking arm. This makes the atmospheric valve surface slightly flexible, enough so that it can self-align to some extent, and by twisting it one way or the other the "play" of the valve can be adjusted. The large drilled channels at the top of each valve chamber travel up to the trunk board to which the 2-tier stack is attached.

(Photographs courtesy of David Ramey, Jr.)

Pouch board for the "rocking-arm" secondary valves. As can be readily observed, the pouch arrangement for the secondary valves emulates the same hinging of the lifting lever at one end as with the primary valve pouches. These secondary pouches, however, differ a bit in that they are somewhat larger than those for the more delicate and sensitive primary valves.