Coil spring loaded
Thanks for posting! Your coil balance shoe looks a lot like the 15-180. Look over the dimensions and compare them to your existing shoe to confirm that this is the right replacement.
The compatible coil springs are the Series 190 coil balance springs. To confirm the springs needed for your assembly, you'll need to search for any stamps on the metal coil. Then you'll be able to select the spring you need from the list shown on the link above. if there are no stamps you'll need to divide the exact window weight by the total number of coils in the window.
You may also need the 15-181 double support detent clip along with the 15-182 coil bushing.
The silver coil to the left appears to have a 7 on it. The other two copper color ones on the right are either a 6 or a 9. The dimensions for the one on the left match the ones you sent me.
The dimension you sent me fit the part I have. The coil spring numbers are different because of different weights of the windows.
The 40 in the stamp number refers to the travel length, the first digit is the spring strength. So, for example, or the coil stamped with a 7, you'll need the S190-740 coil spring.
Regarding the other coils, if you are unable to decipher whether the stamp is a 6 or 9, I would recommend obtaining the exact window weight. Then you'll need to divide that number by the total number of coils in the window.
Do you sell these parts whole or in pieces? I'm willing to try the one stamped 7. I'm willing to try anything you have that is close to making these windows work.
All of my windows that are broken contain only one coil each. It looks like the part you sent me are the ones I need.
These parts are not sold as a complete assembly but they are fairly easy to put together, once you place the order and have them in front of you.
If there is only one coil on each side of the window, that means there are two coils in each window. So you'll need to take those window weights and use the method explained above to select the correct stamp for your window from the list of Series 160 coil springs.
Given that the other coils are stamped with either 6 or 9, it would be best to get the window weight and confirm the correct coil. This means they should weigh either 12lbs or 18lbs. The 7lbs springs would be too strong for the 12lb window and they would not be enough to hold the weight of an 18lb sash.
I hope this helps!