Coinola brand instruments were made by Operators Piano Co., Chicago.
 

Fig. 1-1.  The Coinola worm gear speed reducer is unique to instruments built by
Operators Piano Co.  The design above is the later version with the chain at
the left, nearest the worm gear reducer.  Note also the large hub on the upper
spur gear.  This is a replacement gear made by Boston Gear Co.
 

Fig. 1-2. A later Coinola spool frame with chain on the left.  This example is an
original frame except the upper large gear is a replacement by Boston Gear Co.
Coinola pianos typically have some pot metal gears that need replacing.
 

Fig 1-3. Coinola spool frame with chain on the right.  This is the earlier design.
 

Fig. 1-4. Another Coinola spool frame with chain on the right.  Notice that the
paper winds at the rear of the roll, which is typical of instruments that play the O-roll.
 

Fig 1-5.  Motor in the bottom of a Coinola cabinet nickelodeon.  Round leather belts of
1/4" or 516" diameter drive the spool frame above and the pump at the right of the motor.
 

Fig. 1-6.  Pulley on the Coinola worm gear reducer shaft.
 

Fig. 1-7. Coinola suction pump.  Visible behind the pump are
11 overstrung bass notes of the 54-note Coinola Cupid piano.

Fig 1-9. Coinola Style A Midget Orchestion that plays A-rolls.  The A-roll tracker bar is supported by
cast arms, well forward of the side plates.  Otherwise the design is the same as the later O-roll frames,
with the chain on the left.  The wooden cone pulley has 3 grooves.  The piano was designed to play
O-rolls, so the A-rolls play transposed 5 notes higher than normal.