Grandad opens the Pianola
"Oh, let's see the piano," said Junior. "I've never seen a piano play itself!"
Grandad showed Junior his Pianola. It looked like an ordinary piano, but was a bit deeper.
"That extra bit is for space to put in all the self-playing bit," said Grandad. "Some Pianolas had sort of pedals that made them work, but this one has an electric motor. The motor (or the pedals) works a set of bellows that sucks a vacuum in the insides. Lots of pipes, some big and some quite small, connect from the vacuum chamber to the main parts. There are four main parts in this Pianola, I'll show you them."
So Grandad opened the top of the Pianola and moved two wooden bits that held the front on. Then much to Junior's surprise, he just lifted the front of the Pianola away, and put it carefully on the floor.
Inside was a whole load of stuff! Grandad pointed out the three little bellows on the right, and said "That's the air motor. It is driven by the vacuum from the bellows. When the Pianola is started, the motor winds the paper roll over the shiny brass bar in the middle, which reads the holes in the paper. The motor can be made to go faster or slower, to get the speed of the tune right."
The motor bellows are on the right. roll holder in the centre.
Left of the roll holder, the reddish bellows are used to keep the paper centred
"It doesn't look like a motor," said Junior. How does it work?"
"Well, as the wire shaft turns round it moves those flat wooden slides," said Grandad. "As they move, they connect the bellows to the vacuum at just the right time. The vacuum sucks the bellows closed, and that moves the shaft round a bit. As it turns, the next bellows comes into play, and so on."
"But why so many bellows?" asked Junior. "Won't it work with just one?"
"One isn't enough to make the shaft go right round. It would just wobble a bit," replied Grandad. "By putting more bellows on, and by having the bends in the shaft set just right, the shaft turns very smoothly. Some Pianolas have four bellows, but this one only uses three."
"O.K. I understand that now," said Junior, "But how does it make the paper move?"
"It drives a gearbox that can turn either the bottom or top paper roll," replied Grandad. "When a lever is one way, it slowly winds paper from the top roll to the bottom roll, and the tune on the paper plays. When it's finished, the lever moves over and the motor drives the top roll, very fast, to rewind the paper. When that's finished, it all stops so that you can change the roll."
"How does the paper play the piano?" asked Junior.
"That's the next bit," said Grandad, pointing vaguely to the middle parts of the pianola. "the shiny bit there, between the paper spools, is the tracker bar. This has lots of holes in it, each connected to one of those rubber pipes. Most of the pipes go to the valve chest, where there are lots of valves, one for every note that plays. These are sucked by the vacuum bellows, and when one of the holes on the tracker bar is uncovered, the valve connects to the key mechanism and plays the note, just as if you had played the key. Once the tracker bar hole is covered again, the key is released."
"There seem to be a load of holes there, and a jungle of pipes," said Junior. "How many notes can the Pianola play?"
"This one is an 88-note pianola, so it plays 88 different notes. There are 12 notes in an octave, so it can play seven and a bit octaves. That is enough to play a very low bass note or a very high treble note."
"But can it only play one note at a time?" asked Junior
"Bless you, no," replied Grandad. "It can play lots of notes together, just like a person would. In fact, a person has only ten fingers and thumbs, but most Pianolas can play many more keys than this at the same time. It really depends on how strong the vacuum pump is. Just remember that every note needs a hole or slot in the paper."
"What are those lines of holes close together on the paper?" asked Junior. "Does it play a note for each hole, like when I whack my finger up and down on a key?"
"Not if they are very close together," replied Grandad. "If they are close, there isn't enough time for the key to come back up before it gets pulled down again. What happens is that the vacuum keeps pulling, but more gently once the key first operates. That way isn't such a strain on the pump if lots of notes need to hold for a long time."
"I bet it helps to stop the paper roll from falling apart, too!" said Junior.
Junior had been looking more closely at the tracker bar. He said "I've noticed that there are more than 88 holes, Grandad. And there are some bigger holes at the ends of the tracker bar."
"Yes," replied Grandad. "Those are all used for another part of the Pianola. Some are used to work the sustain and soft pedals, just like the pianist would do with his feet. Another one, when it is uncovered, makes the playing stop and starts rewinding the paper onto the top roll. Another one, that gets uncovered when there is no paper left, stops the motor and switches off the player. There are more holes as well. They work those bellows down at the bottom of the Pianola, to alter the amount of vacuum fed to each half of the keyboard and make it louder or softer. Not all rolls or Pianolas can do this bit, but this Pianola can. It is supposed to make it sound more like a real pianist."
Grandad dipped down and lifted off the big panel across the bottom part of the Pianola. They looked inside.
"The big bellows at the bottom in the middle are the vacuum pump. The big rectangles of felt are silencers, to stop the noise of the flap valves and the suction. The electric motor on the right drives them, geared down by two sets of Vee belts and pulleys. The bellows are in pairs, one in front and one behind that you can't see. That's six bellows altogether, all sucking in turn like billy-o to get a really good vacuum. The motor switches on when you start it playing, and turns off when the paper runs off the tracker bar. The belts reduce the motor speed so that the bellows are pumped at just the right speed. It is a quite powerful motor, so you must keep well away from it and from the bellows or it could be dangerous. At the left you can see the little bellows driven by the 'extra' holes in the paper roll, that adjust the vacuum and control how hard the keys are struck."
Junior said "Those bellows look as if they are put one on top of the other!" "They are," replied Grandad. "That way, they can work with one another to get even more combinations. Have you learned binary numbering yet?" "Yes," replied Junior, "I know how it works. So with four bellows you can have sixteen different settings?" "That's right," said Grandad. They are the only part of the Pianola where holes on the tracker bar work together, and don't just do one thing. Each half of the keyboard can separately be given a different loudness, because there are two sets of those binary bellows."
"Can we listen to it now?" asked Junior.
"Okey Dokey," replied Grandad, looking for a roll to play.
"What sort of music can be played on this pianola?" asked Junior.
"A lot of people bought them to play Classical music, often using 'expression' rolls originally played by famous pianists. I have hundreds of classical rolls, but they are not really my cup of tea."
"What do you listen too, then?" asked Junior.
"I like something with a strong rhythm," replied Grandad. "Especially Jazz and 'stride'."
So they listened to a piano roll of Fats Waller playing 'Handful of Keys' and watched all the bellows and shafts moving as it played.
"When was this Pianola made?" asked Junior.
"This one was made in 1921," replied Grandad. "The piano part was built by Steinway in Hamburg, then on the 11th of April 1921 was sold to Aeolian to have the Player parts fitted and then to be sold as a complete item."
"When these were finally sold to individuals," said Grandad, "The salesmen were told never to let prospective customers look inside the Pianola at the works, but just to get them to close their eyes and imagine a concert pianist sitting there playing the keys. They believed that the complicated mass of stuff inside would frighten people off and prevent them buying one."
"What! Not see how it works!" said Junior, shocked. "I wouldn't buy one if I couldn't see all that stuff working!"