| 摘要 |
<p>A pair of oppositely wound torsion springs and a pair of oppositely wound spiral ribbon actuators therefor are provided in a unitary construction as a Window Sash Balance. There are torques developed between each of the spiral ribbon actuators and its respective spring. The two torques are in opposite directions and cancel each other. This eliminates torque which would otherwise, when applied to the window sash, increase the friction between the sash and the window jamb and make difficult the operation of tilt type and removable sashes.</p> |
