US Patent 10472871 Window balance having four-loop cord configuration

A window balance has a channel with two ends. A top guide is disposed at one end of the channel and a bottom guide is disposed at the other end of the channel. One end of a spring is fixed within the channel. A movable block is secured to the other end of the spring. Rollers are rotatably mounted in the movable block. A single roller is rotatably mounted to a fixed block which is secured to the channel. A cord exit roller is disposed proximate the bottom guide. The first end of a cord is fixed relative to the channel. The middle portion of the cord is routed about the rollers mounted in the movable block and mounted to the fixed block. A second end of the cord is routed around the cord exit roller and is attachable to a window jamb.