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MMD > Archives > February 2008 > 2008.02.23 > 03Prev  Next

Duo-Art Motor Running Continuously
By John A. Tuttle

Hi All,  Jeffrey's question should have but one answer _if_ the
electric motor has been restored and the expression system is
correctly adjusted.

In a correctly adjusted Duo-Art, there is a relatively large vacuum
leak to the atmosphere until it reaches level 9.  At level 10 (8+2),
that leak is closed, and full vacuum is applied to the expression
mechanism.  With no notes playing, that will put a tremendous strain
on both the rotary pump and the electric motor.  However, if the belt
between the pump and motor is correctly adjusted, the belt should slip
when the vacuum level in the pump reaches about 40-50 inches of water
vacuum (depending on the size of the Steinway).

In my opinion, he will be lucky if all he has to replace is a burnt out
belt.  And once the belt burns out, the motor should be fine, and the
rotary pump will have stopped turning.  If he's not so lucky, it's hard
to say whether the pump or the motor will fail first.  I suppose it
depends on the vacuum level in the pump and the amount of drag on the

In my opinion, the motor would seem to be the greatest concern.  As it
starts to overheat, the bearings will get tighter and tighter, and they
may eventually seize.  Should that happen, the motor current will reach
maximum and hopefully the circuit breaker will pop before the motor
catches fire.

Looking at the other possibility, the damage done to the pump depends
a lot on the newness of the cloth.  The stress of operating at the
maximum vacuum level will undoubtedly put a heavy strain on the cloth,
and it will most likely develop holes at the folds.

What I would do is call the neighbor to whom I gave a set of my house
keys before leaving, and tell them to turn the unit to Off.  But then,
maybe I'm one of those unusual folks who trust my neighbors enough to
give them a set of my house keys and car keys in the event that there
is a need to get into my house or move my cars while I'm away.  (P.S.
I also have them collect my mail and any parcels that get dropped off
by delivery people.  And yes, I have great trustworthy neighbors...)

Or, barring the above, I'd call the police and ask them to break into
my house and turn off the power.  What's more valuable: a door lock,
a window, or a Steinway Duo-Art grand?  You do the math!

John A Tuttle
Brick, New Jersey, USA

(Message sent Sat 23 Feb 2008, 15:10:57 GMT, from time zone GMT-0500.)

Key Words in Subject:  Continuously, Duo-Art, Motor, Running

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