TANGLEY CALLIOPE RESTORATION PROJECT (part 11)
by Dr. Bill Black
THE AIR MOTOR
Rather than using an electric motor to turn a crankshaft which then powers the roll frame like a Wurlitzer band organ, the Tangley Calliope uses an air motor similar to those used to operate the spool box in a player piano. This air motor is actually operated by the vacuum supply which also operates the stack and other control mechanisms for the calliope.
PHOTO A shows the unrestored air motor. On the left side of the photo, there are two nipples on a small block mounted on the air motor. The smaller nipple on the side of the block is connected to the air motor we discussed last month. This vacuum source is regulated and allows for control of the speed at which the air motor runs and thereby the tempo of the music by controlling the speed of travel of the music roll. The larger nipple on the top of the block, provides a higher level of vacuum from the rewind shifter control to allow the air motor to operate at a higher vacuum level and therefore a faster speed for rewinding the music roll.
The air motor is comprised of a group of 5 pneumatics joined together by metal strips and interconnecting nipples which provide the vacuum supply for each pneumatic. On top of each pneumatic there is a mounting block with a slider valve. On the bottom of each pneumatic there is an arm which is connected to a wooden push rod which is connected to a crankshaft. The action of the pneumatics opening and closing in sequence cause this crank shaft to rotate. On the end of this crankshaft is mounted a sprocket which serves to power the roll frame by means of a chain which connects the air motor to the roll frame.
PHOTO B shows the air motor turned upside down.
PHOTO C shows a closer view of the slider valves on the tops of each pneumatic. Each slider valve is connected to a wooden push rod (PHOTO D). These slider valves have wire guides to prevent sideways movement and allow for a fore and aft movement. Note how the hole in the mounting block can be covered and uncovered as the slider moves back and forth. When the hole is covered, this arrangement allows vacuum to be applied to the pneumatic and it collapses. As the crankshaft rotates, the slider valve is moved and the hole is opened. Atmospheric air pressure enters , the vacuum is overcome and the pneumatic opens. This sequential opening and closing of the pneumatics and the movement of the slider valves produce a rotation of the crankshaft which powers the roll frame.
PHOTO D shows a closeup of the connection between the slider valve and the wooden arm connected to the pneumatic and the crankshaft. This is an adjustable link which allows you to adjust the timing of the operation of the pneumatics to permit a smooth rotation of the crankshaft.
PHOTO E shows the disassembly of the air motor into the individual parts.
Dr. Bill Black is one of the nation's most knowledgeble Wurlitzer band organ experts. He has made recordings of many band organs and other mechanical music machines which are available for purchase in our CarouselStores.com website.