BLOCK AND TACKLE WINDOW BALANCE

摘要

A block and tackle window balance includes an extension spring and two blocks of pulleys mounted within a rigid channel. A spring coupling connects a free end of the extension spring to the first block of pulleys. The pulleys of the first block are sized in width to center the spring coupling and the free end of the extension spring within the channel. The second block of pulleys are mounted on an axle that is received in slots formed in the channel. A center portion of the axle guides a pulley cord through the second block for exiting the balance.