Here is a picture of 2 Elgin movements both 23 jewel the grade 730 and grade 750 ..

I bought the grade 730 about a year ago with a broke pivoit on the escape it was in a nice lord elgin i got around to working on it today and thought i would take a few pictures of what i think is one of Elgins best movements..

the 730 used in the B.W. Raymond railroad approved watches..

you can see in this pictutre a ruby pin that was used instead of a steel pin on the intermediate winding gear looks similar to the ruby banking pins used on the Keystone Howards.

Samie,
What's the purpose of the clamp around the balance wheel? I have a couple of these and have no idea of how they are regulated. I think a weight or weights may be moved toward and back from the rim of the balance wheel on the curved spokes, but can't see how that can be done without risk of severe damage to the hairspring and pivots by indiscriminate poking about.

John,

I think you're right about regulating. This is what Elgin had to say about it at the time. To quote from the 1958 Elgin Service Manual...

a) The new Elgin DuraBalance assembly is the most advanced timekeeping device for modern wristwatches to be introduced in recent years. It offers five major benefits...

1) Better timekeeping
2)Simplicity in adjustment and regulation
3)No hairspring tangling
4)Improved shock resistance
5)Reduction of oil troubles

b) With the Elgin DuraBalance assembly, the regulator is eliminated. Timing is not affected by variation in hairspring length. Timing depends on the moment of inertia in the balance. This can be easily varied by changing the position of the movable weights. Timing is, therefore, virtually independent of balance motion. This means that the watch keeps exact time for a longer period with less isochronal error. The principal of the new Elgin DuraBalance may be likened to a governor. As the weights are moved toward the staff, the timing speeds up; as they are moved toward the rim, the timing slows down.

And later, after the sales pitch...

18.3 Regulation

a)With the balance assembly still in place in the watch, stop the balance with pegwood, tool or finger.

b)Move the regulating lever slowly, with a pointed piece of pegwood or tweezers, the distance required to regulate timing:
1)clockwise to advance (faster).
2)counter-clockwise (slower).

c) Distance between timing marks equals 90 seconds.

18.4 Cleaning

a) Remove complete balance assembly.
b) Clean assembly complete, by hand, without any disassembly (to avoid possibility of damage.)
c)Replace assembly in movement, making sure that stud is back in original position.

Note" If cleaning is done properly, no hairspring centering or correction, and little or no timing regulation will be necessary.

There is also a note saying...

Service of the DuraBalance assembly should be confined to regulating and cleaning as described above. Other service of the DuraBalance assembly will be provided by the Elgin National Watch Company.

Later editions of the manual provide rather complicated instructions for staffing and poising the DuraBalance wheel.

Regards,

Cary

Cary,
Thanks! That's very good to know. I doubt I will try to regulate mine; for me poking about that close to a hair spring would be disastrous.

John Cary did a great job explaining the Dura balance i use a small screwdider to make adjusments on these but you sure need to take your time or you can damange the hairspring..

I have found these movements to be great timekeeper if in good condition some folks don,t like these but i think they are very good movements.