Grahame Code asked in 010628 MMDigest about a substitute motor in
order to operate the Welte Vorsetzer from the 240 vac mains in
Australia.  Aspects to consider include cost, availability, ease of
installation, range of speed adjustment, and noise (hum).  These
options are conceivable:

1.  If the existing 110-volt Welte motor is serviceable then one can
employ a simple step-down transformer to change 240 vac to 110 vac.
Ask about a transformer at an electrical supplies firm, or at an
old-time firm which deals with 110-volt appliances from Japan and USA,
etc.  A transformer rated for 1 kilowatt (or 1 horsepower) should be
more than adequate.

This option is least cost, most readily available, easiest to install
(because it's external) and there is no change in motor speed
adjustments and motor noise.

2.  Obtain an original 220-volt motor *and* the associated resistors
from a Vorsetzer built for 220 vac service in Europe.

This option is likely to be quite expensive and it will be difficult
to locate a motor for sale; the installation will be straightforward;
motor speed adjustments and motor noise will be unchanged.

3.  Substitute a similar adjustable-speed AC motor.  As I recall,
the motor furnished with the Welte-built Vorsetzer is a compound- or
shunt-controlled variable speed motor, such as was used many years ago
in industrial applications that required smooth and continuous speed
adjustment.

This type of AC motor is rarely seen nowadays in fractional horsepower
sizes; it will be hard to find a suitable motor and it will be quite
expensive.  Installation will be fussy but manageable; some fiddling
with the resistors will be needed to match the speeds of the original
Welte motor.  The noise level probably will be equivalent with the
Welte motor.

4.  Substitute a similar 220-volt shunt-connected DC motor and simple
DC power supply, using the same basic field-current speed control
circuit with switched resistors as with the Welte motor.  Acceleration
can be adjusted by a resistance in series with the armature.

This type of motor has been used in industry (and in player pianos!)
for over 100 years, including in fractional horsepower sizes, and is
relatively easy to find.  The commutator noise will be no more than
with the Welte motor; if well-filtered DC is applied there will be
no motor hum.

The cost will be a little more than an induction motor, but all the
control features of the Welte motor system are retained.  Installation
and adjustment will be similar to the adjustable-speed AC motor option.

5.  Substitute a modern permanent magnet DC motor and electronic
speed control unit for 220-240 vac 50 Hz mains.  It should include an
adjustment for acceleration/deceleration.  The speed control circuit
can be modified by the vendor to provide separate controls for "fast"
and "slow" speed as commanded by the switch in the Vorsetzer mechanism.
The controller must be specified to output well-filtered DC, else the
motor hum will be objectionable.

The cost of this option is more than a simple AC induction motor but
probably less than the cost of a Welte motor or equivalent.  The
DC motor and controller is readily available from an industrial motor
supplier, who will also modify the controller for dual speeds.
The installation will be straightforward.  It will be easy to adjust
the two speeds and acceleration characteristics to match the operation
of the original Welte motor and its resistors.  With well-filtered
current from the motor controller the motor should be inaudible.

6.  Adapt a modern two-speed induction motor.  A fractional horsepower
2-speed induction motor is often used to spin the squirrel-cage blower
in an evaporative ("swamp") cooler for the house.  I examined one of
these motors installed in a Wurlitzer coin piano.  It seemed actually
to be two independent motors: a 4-pole and a 6-pole motor sharing a
common shaft in one rather long housing.  A 50 Hz motor like this would
be labeled at approximately 960 and 1440 rpm.

The cost is moderate and it's readily available.   However, an
intermediate jack-shaft with belts and pulleys is likely to be required
to get adequate speed reduction, and the speed ratio is fixed at 2:3.
A relay will be needed to change the motor connections to select high
or low speed, and the "clunk" of the relay is likely to be annoying,
and also the distinct click from the internal motor start switch.  The
hum of a commercial induction motor is often noticeably louder than
from a motor designed for player piano service.

7.  Dispense with the two-speed system.  The two-speed system of the
Welte-Mignon Vorsetzer was employed simply to reduce the noise of the
motor and pump when large air flow was not needed.  Later Welte
"Licensee" player systems, built in USA after WW1, operated the pump
at one speed and used the same pump motors as in other reproducing pianos.

Therefore, substitute a quiet 6-pole 50 Hz induction motor of about
960 rpm and select the motor pulley diameter so that the pump
speed is the minimum needed for the most demanding musical passages.
The excess air flow during quiet passages will be spilled by the
existing pump spill valve.

The cost is moderate and installation is straightforward.  The motor
can be a reconditioned old player piano motor (best) or a modern
960 rpm blower motor (noisier, more hum).

Best regards,

Robbie Rhodes
Etiwanda, CA