ADJUSTABLE FRICTION BLOCK AND TACKLE WINDOW BALANCE SYSTEM

摘要

A block and tackle window sash balance system 10 has its friction made adjustable by a friction spring 20 and a cam 30 arranged for pressing spring 20 against a radial face of a pulley 15 in a high friction position and moving the spring clear of the pulley in a low friction position. Cam 30 is preferably accessible with a screwdriver for adjusting friction after the balance is installed in a window.