Window balance systems

A block and tackle window balance system comprising:

• an elongated channel;
• a fixed pulley coupled to the elongated channel;
• a movable pulley slidably disposed within the elongated channel;
• a cord extending between the fixed pulley and the movable pulley;
• a spring coupled between the elongated channel and the movable pulley;
• and
• a locking device movable between at least a locked configuration and an unlocked configuration with respect to the cord, in the unlocked configuration, the cord is movable with respect to the elongated channel such that the elongated channel is slidable within a window jamb, and in the locked configuration, the cord is engaged such that the elongated channel is held in place within the window jamb.

A window balance system for a tilting window sash, the window balance system comprising:

• an elongated channel configured to couple to the window sash;
• a fixed pulley coupled to the elongated channel;
• a movable pulley slidably disposed within the elongated channel;
• a cord extending between the fixed pulley and the movable pulley;
• a spring coupled between the elongated channel and the movable pulley;
• and
• a locking device movable between at least a locked configuration and an unlocked configuration with respect to the cord, wherein in the locked configuration, the window sash is in a tilted position and the locking device engages the cord so as to hold the elongated channel in place, and in the unlocked configuration, the window sash is in a vertical position and the locking device allows the cord to slidably position the elongated channel.