The lost motion device is a refinement that was installed in _some_
of the later model "A" Ampico player units, and is usually found in
all of the model "B" units.

Assuming the pneumatic stack is adjusted properly, with no lost motion
between the poppets and the piano action at rest, when the soft pedal
is called for, it moves the hammer rail in a position closer to the
strings for softness.  When this occurs, it creates a small space between
the poppet striker and the piano action.  The small gap can produce a
very slight thud sound and also a very slight delay and unevenness in
the playing of soft notes.  The majority of people do not hear this,
yet for those who do, it can be quite annoying.

The lost motion device is a pneumatic mechanism which compensates for
this small spacing between the piano action and the player action when
the soft pedal is activated.  It is _only_ activated when the soft pedal
is called for.  Its supply is connected to the soft pedal valve block,
or tee'd to the soft pedal pneumatic.

In the Ampico grand, the device is usually found built into the
pneumatic stack, and can be identified by three or four pneumatics
larger than the striking pneumatics.  They are usually covered with
motor cloth, rather than pneumatic cloth.  The pneumatics are connected
together, and feed from one supply in the soft pedal, or soft pedal
valve block.

In the Ampico upright the lost motion device is somewhat rare.  If
installed, it is usually found under the key-bed, and is mechanically
activated by a rod extending upward.  The rod lifts a rail on the
pneumatic stack, raising all of the poppets to follow the piano action
movement when the soft pedal is in use.

Ampico was not consistent in the placement, or connections of various
improvements.  Some are found in different locations, and some were
never used, or never installed.

To adjust the lost motion device, compress the soft pedal pneumatic,
(hammer rail lift in grands) either mechanically, (with a clamp) or
with vacuum when the motor is on, and lightly press upward on the
striking pneumatics.  If there is noticeable movement before the piano
action starts to activate the piano hammer, (lost motion) the travel of
the lost motion pneumatic(s) should be increased until the space between
the poppets and the piano action is reduced to zero.

It is very important that there is absolutely no leakage in the lost
motion pneumatic or pneumatics.  The supply is very small, and the
mechanism has a lot of work to do.  A small leak will render it
ineffective.

Some of the very late model Ampico systems are lacking many of the
earlier refinements.  After the Ampico "B" was introduced, some model
"A" expression units remained, and were connected to "B" drawers in the
grands.  Some had lost motion devices and others did not.  I believe
Ampico realized the end was near, and started to use many older style
parts that had been packed away in their warehouses.

In addition, I believe Ampico eventually realized many Ampico owners
were not as critical of music produced by the Ampico as they had
originally assumed.  A properly adjusted, disabled, or missing lost
motion device might not be noticed by the average listener.

Bruce Clark, Ampico technician (retired)