Patent ID: 8997313
Filing Date: 2015-04-07
Classification: E05F,Y10T

Abstract:
1. A counterbalance mechanism comprising: a first attachment strap; an arbor attached to the first attachment strap; a second attachment strap rotatably supported by the arbor and rotatable relative to the arbor about a winding axis; a spiral spring interconnecting the first attachment strap and the second attachment strap, and including a plurality of coils wound about the winding axis, wherein the spiral spring is operable to bias the first attachment strap and the second attachment strap angularly relative to each other about the winding axis; and a spring support attached to the second attachment strap and including an annular wall disposed circumferentially about and concentric with the winding axis; wherein the annular wall is radially positioned relative to the winding axis to contact an outermost coil of the plurality of coils to position the spiral spring in a spiral orientation about the winding axis; wherein the second attachment strap includes a positioning mechanism operable to position the annular wall of the spring support relative to the second attachment strap such that a central axis of the annular wall is co-axial with the winding axis; and wherein the positioning mechanism includes at least two tabs formed by the second attachment strap and positioned to contact the annular wall of the spring support when the spring support is positioned with the central axis of the annular wall co-axial with the winding axis.