US Patent 9458655 Constant force moving coil window balance with drop-in carrier

The disclosure provides a window balance assembly for installation in a window assembly. The window balance assembly includes a carrier, a curl spring, and a mounting bracket. The spring element includes first and second portions. The first portion is contained by the carrier and the mounting bracket engages the second portion. The carrier has a first housing including a channel formed in an exterior side of the first housing and an aperture in which a receiver is included. The channel extends vertically upwardly from the aperture toward the top end of the first housing portion to facilitate a full-drop-in installation and removal of a window sash from the window assembly.