SWISCO - The Replacement Hardware Authority

Block and tackle balance information

A quick learner from DENVER, CO says:
ARE BLOCK AND TACKLE BALANCERS DESIGNED TO CARRY A RANGE OF WEIGHTS?

LETS SAY YOU HAVE A SASH 40W X 30H AND ANOTHER 20W X 30H. WOULD THEY TAKE THE SAME BALANCER? IF YES HOW IS THE DIFFERENCE IN THE FORCE THAT THE BALANCER DELIVERS TO LIFT THE SASH ADJUSTED SO THAT THE WINDOW OPERATES NICELY?
IF NO WHAT IS DIFFERENT BETWEEN THE BALANCER FOR THE 20 WIDE SASH AND THE BALANCER FOR THE 40 WIDE SASH SINCE THEY ARE THE SAME HEIGHT AND THE WEIGHT SHOULD BE AROUND DOUBLE.

I HAVE BEEN IN THE INDUSTRY FOR 20 YEARS - NEITHER COMPANY I WORKED FOR USED BLOCK AND TACKLE. I AM GOING TO TRAVEL TO INTERVIEW AT A COMPANY THAT USES THEM AND I NEED TO GET SOME KNOWLEDGE OF THIS SYSTEM. YOUR HELP WILL BE GREATLY APPRECIATED.
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Paul from SWISCO responded:
A block and tackle balance is a window balance system that uses a spring and pulley system to hold the sash up. The manufacturer stamps these balances with certain codes (we call them "stamp options") that indicate the strength of the spring. Two balances may have the same Series and length, but two totally different strength springs. You should definitely weigh the sashes to determine exactly what stamp option would be best in each circumstances.

Most of the balances on our site have a chart on their store page that associates each stamp option with a specific weight range.
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