Spiral balance spring

Question

This spring broke into two parts. It fits Pat. 5,353,548 do I order a 7 spring?

Bob · Accepted Answer

I am afraid patent numbers really aren't that reliable, as many different pivot shoes can use the same one. I believe you might have our 15-087 though, which uses the Series 180 Coil Springs. Please confirm. If so, yes, a 7 stamp means you can use the S180-7 7 pound spring.

Series 180 coil balance diagram