Abstract: A pivot shoe which slides in a track includes a body which receives a cam. The cam is rotated by a sash pivot shaft for engagement of a wall of the track by the shoe for resisting movement along the track when the sash is rotated on the shaft to a position generally perpendicular to the track. The cam defines a first axial opening for receiving the shaft, and defines a second radial opening for removing the shaft from the cam. The body defines a third radial opening which is in alignment with the second opening when the sash is rotated to the track engaging position. A reversible obstructor for the second opening provides for easy installation or removal of the shaft from the shoe.

Abstract: A body for sliding in a track, and a rotary barrel cam. One portion of the body has two legs defining a separation zone between them for divergent movement of them. They further define within the zone, a passage in the body, for receiving the barrel cam. The barrel cam is mounted in the passage for rotation, about an axis that is generally normal to one wall of the track.The barrel cam and the body define between them an axial thrust cam for forcing part of the pivot shoe axially with respect to the axis, against an inner surface of the track when the barrel cam is rotated.An axially slidable brake pad is located over the barrel cam for engaging the inner surface of the track when the barrel cam is rotated.The barrel cam and the body also define between them a radial thrust cam for forcing a leg radially with respect to the axis against an inner surface of the track when the barrel cam is rotated.The body is adapted for receiving external elements for urging the body along the track.

Abstract: 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 jam and make difficult the operation of tilt type and removable sashes.