Wurlitzer Style 17 (Regular) PianOrchestra
Philipps Pianella Model Special
Trapwork Valve Chest

(Photographs courtesy of David Ramey, Jr.)

The trapwork chest sits squarely on the top chassis shelf directly above the roll mechanism, and in front of the pipe chest. It contains fifteen valve sets—a primary valve and a secondary valve make up each set. The primary valves connect directly to the appropriate tracker bar hole. The valve set at the extreme left operates the snare drum, while the extreme right hand valve set operates the bass drum and cymbal. The thirteen valve sets in between play the orchestra bells, for which the loose rubber tubing flopping down from the chest would normally be connected to the pneumatics in the bell action.

(Photographs courtesy of David Ramey, Jr.)

Peering down into the right hand side of the trapwork chest. The brass elbow at the right is for the bass drum and cymbal, the other visible secondary valves are for the bells. The primary valves are not visible, and operate the little pneumatics that lift the larger secondary valves.

(Photographs courtesy of David Ramey, Jr.)

This view shows both the primary and secondary valves as they appear in the main board with all covers and tubing headers removed. The primary and secondary valves are of the same center wire stem type, with the secondaries larger and lifted from the top, as opposed to the smaller primaries that are lifted by an internal pouch.

(Photographs courtesy of David Ramey, Jr.)

This side view peers into the inside of the chest. The valve board is at the top, with punched metal valve seats, and the pouch board is on the bottom. Notice that each primary valve pouch is fitted around and glued to its own little wooden block. This may have enabled whomever was building up a new chest to grab a handful of pre-made pouch units and quickly glue them in place, but in later years this idea was abandoned for the more common pouch board design that consisted of a series of round recesses bored part way into the board and with a stamped out circular piece of zephyr skin or pouch leather glued over the hole. Both designs served the same function, but the latter was less work to manufacture.

(Photographs courtesy of David Ramey, Jr.)

Top view of the right hand part of the pouch board. The little rectangular piece of fiber glued to the center of the pouch is what presses against a felted leather nut at the bottom end of the primary valve's wire stem.

(Photographs courtesy of David Ramey, Jr.)

This view shows a primary valve to the left, and a secondary valve to the right. Both valves are similarly constructed, but of different sizes, and the primary valve at left is lifted from the bottom, while the secondary valve at the right is lifted from the top. Both wire stems have rolled threads at one end to accommodate a leather nut, and within the valve body there is a small flange secured to the wire, around which the valve body is assembled. This tiny flange keeps the valve body from slipping up or down on the wire stem, while simultaneously allowing the valve surfaces to be flexible enough to self align with the stamped metal valve seats. Looking at the secondary valve at right, the upper leather valve surface and underlying fiber washer rest on and above the flange. This is why there is a slight separation between the upper and lower parts of the valve. The lower part consists of a leather valve surface glued to a fiber washer, whereupon this unfinished part is then slipped over the wire stem up to the flange. Then another piece of valve leather is glued to the other side of the fiber washer, essentially locking this part of the valve assembly around the tiny flange, but it still remaining flexible enough to self align with the valve seat.

(Photographs courtesy of David Ramey, Jr.)

The above is an exploded view of a secondary valve. At far left is a typical leather nut. Next to it is an action cloth bushing, which is tougher and holds its shape better than would a simple felt punching. Next is a leather punching that serves as a valve face, of which there would be two similar leather faces for each valve—one for the vacuum interface, and the other for the atmospheric vent. To the right are fiber washers, which maintain the structural integrity and flatness of the valve unit. The fiber washer near the center of the image is for the atmospheric vent, and is nothing but a flat fiber punching. The fiber washer at its left is a shallow recess that provides some space for the wire stem's tiny flange. The wire stem laying horizontally below the other valve components has rolled threads on its top (left side) end, and is fitted with a small tapered flange secured to the wire stem at about the center point of the valve body.

(Photographs courtesy of David Ramey, Jr.)

The above line drawing is from U.S. Patent Application No. 730,565, Pneumatic Action for Musical Instruments, which was filed by J. D. Philipps on November 28, 1902, with the patent issued on June 9, 1903. This is the basic idea and layout behind the trapwork chest in the Style 17 PianOrchestra, and for all known early Mandolin and Concert PianOrchestras. In actual practice, however, simple stamped metal valve seats were used, instead of the more arduous to make wooden construction shown. Notice that this drawing does not show pouch blocks, as in the Style 17's trapwork chest, but instead illustrates the commonly used pouch board design using holes bored part way through the board. Moreover, the drawing also shows a bleed hole within the chest itself, and connected to the channel going to the pouch. This bleed placement was not used for any known PianOrchestra, because the bleeds were located within the tracker bar.