A-250 Safety Stop (start and stop mechanism) Observed

[fran604g]

Hi folks,

In the spirit of sharing knowledge, I thought I should create a separate post of the results of my small reearch project I started here: http://forum.talkingmachine.info/viewto ... 11&start=0

I hope you find these results informative and useful, and that this post isn't seen as too redundant.

With data I've collected so far, combined with my own observations, it appears that there were three versions of the levers used for the A-250 start and stop mechanism. I show them below in the chronological order that I think they were utilized. For clarification purposes, I will refer to them as; TYPE 1, TYPE 2, and TYPE 3 respectively.

All three versions of levers were used in tandem with a "finger": a curved metal piece mounted to the horn pivot shaft under the operating handle. In Edison literature this arrangement of levers and a finger was referred to as the "Safety Stop".

The finger part of the safety stop also changed throughout the production of the A-250 - from a pivoting one to a rigid one - but I don't have enough data to adequately express its evolution yet.

The safety stop appears very early on the A-250, and was probably used on all Type A mechanisms in some form. Eventually, it was carried over to the Type B mechanism, and was the standard for Diamond Disc Phonographs.

Because of the Edison company's well-known propensity to use up "older" parts in "newer" designs, these three versions may have been intermingled during the transitional periods they were implemented.

MY FINDINGS SO FAR:

TYPE 1 - This appears to be the earliest arrangement.

TYPE 2 - This arrangement appears to be an obviously simplified - and more economical - design than the TYPE 1.
NOTE: This is a picture of the TYPE 2 on an A-150, and is the same arrangement that is on Garrets A-250 referenced in this post: http://forum.talkingmachine.info/viewto ... 54#p113954

TYPE 3 - This version added an adjustable link to the stop lever, and is the version that was used throughout the many years that the Type B mechanism was utilized.

My sincere thanks to Dustie89, Valecnik, and Phonogfp for the 3 photos I used in this post. I would like to also thank the others who have posted their A-250 information.

This is a pursuit for knowledge, and as always, I appreciate additional comments and insight.

Best,
Fran[/quote]

[phonogfp]

Thanks for laying all this out, Fran. I've never seen the evolution of the Diamond Disc Phonograph brake illustrated like this - - not even in Frow.

Nice work!

George P.

[fran604g]

Thanks for laying all this out, Fran. I've never seen the evolution of the Diamond Disc Phonograph brake illustrated like this - - not even in Frow.

Nice work!

George P.

Thank you for the kind words, George!

Fran