Collaro D30 Spring Measurements.

[Frankia]

I'm trying to find out what the original spring specifications were for the largest of the Collaro spring motors - the D30?
Does anyone know?

[epigramophone]

According to my Vulcan mainspring catalogue the specification is as follows :

Dimensions 1" x 0.028" x 15'6" (25 x 0.70 x 4750mm)

Pear shape outer end with hub centre.

The Vulcan Catalogue Number was 616 and the spring was listed as suitable for the Collaro D30 and 202, and the Columbia 50 and 100.

Knowing that the spring fitted several different motors may make it easier to source.

Roger.

[Frankia]

Thanks very much for that Roger. Coincidentally, someone else found the same source a short while ago! Apparently the Garrard 10b motor also takes the same spring, is that right?
If so, I'm interested in the fact that Collaro advertised their D30 motor as being capable of getting through four 12 inch 78s. However the Garrard 10b is a three record motor, at least going on the good condition example that I have here. I've tested my D30 for play length, and while it can't quite manage four records, it runs quite a bit longer than three - more like three and two thirds or three quarters, depending on record length.
Being a mechanical infant, I ask for patience with the next question! Does this simply mean different gearing in the two motors?
I ask because I want to be absolutely sure I'm getting long enough springs before going any farther.
Thanks.

[epigramophone]

For some reason the Garrard 10B is not listed in the Vulcan catalogue, but the 10A is, and has an even longer spring measuring 1" x 0.026" x 16'9" (25 x 0.65 x 5075mm).

My catalogue is a photocopy, but when time permits I will scan and post it on the forum as a technical resource.

Roger.