Design difference in between Rolex movement Cal.1520 and Cal.1530

[ecc803]

The difference in between Rolex movement Cal.1520 and Cal.1530 is the running speed.
Rolex Cal 1520 running speed 19800 beat
Rolex Cal 1530 running speed 18000 beat

Seems that the balance staff height and dimension do not have difference.
I know there is difference from the hairspring.
Does anybody know what is the difference from the 1st, 2nd and 3rd wheel?
For example:
How many teeth from each wheel?

Thanks in advance.

[toph]

All i can say is that that the 1530 is the base caliber for many movements, it is actually 28,5mm x 6,30mm whereas the 1520 is 28,5mm x 5,75mm- so that would suggest a difference in size. But the 1530 is the base caliber for the 1520.
Sorry i cannot be of more help.
:cheers:

[mike]

I would defer to the watchmakers for major differences. I believe the 1520 was available at one time with either 17 or 26 jewels. This was due to where the watch was destined for sale to offset tariffs.
The 1520 used a flat hairspring instead of a Breguet overcoil, and a stick regulator instead of the microstella version.

As to the number of teeth, I don't know.

[ecc803]

Thanks TOPH & MIKE,
I hope I can find the difference myself (During the overhaul). Will keep you posted.
Does anybody know, please provide hints to me. Thanks in advance.

[ecc803]

Overhaul Cal 1520, compare the 3rd wheel, 4th wheel and escapement. The difference in between 1520 and 1530 is the 3rd wheel.
As mentioned, the Calibre 1520 balance wheel running in 19800 beat.
The Calibre 1530 balance wheel running in 18000 beat.
From technical point of view, the 1520 is better.

[mike]

Great info. Thanks.:thumbsup::thumbsup: