GB819094A - Adjustable foot mechanism for sash balances - Google Patents

Abstract

819,094. Spring - balanced windows. UNIQUE BALANCE CO. April 8, 1957 [May 1, 1956], No. 11416/57. Class 20(3) Mechanism for adjusting the tension of the inner helical spring 22 of a conventional two-spring spiral sash balance, also having an outer axially-extensible helical spring 11, comprises a foot plate 36 which is secured by a rivet 37 to a short plate 40 and carries, at its upper end, a tapered sleeve 52 which frictionally engages within the lower end of the outer spring 11, the plate 40 carrying a pawl plate 41 with a central aperture 55 and pawl teeth 58. A stop 42 on the lower end of the plate 40 projects through a slot 45 in the plate 36. A ratchet plate 56, having notches 57 to engage the teeth 58 and opposed inwardly-extending teeth 60, is urged downwardly on to the pawl plate 41 by a helical spring 22 contained between the lower face of the sleeve 52 and the ratchet plate 56. An adjusting member 46 has a lower flange 47, a collar 48 and a tubular extension 51 which fits within and projects beyond, the tapered sleeve 52 frictionally to engage within the lower end of the torsion spring 22. A transverse slot 50, extending through the flange 47 and collar 48 and into the lower end of the tubular extension 51 engages the inwardly directed teeth 60 on the ratchet plate 56. To insert the adjusting member 46 the slot 50 is first aligned with the rivet 37, then it is turned through an angle of 90 degrees so that the teeth 58 engage the notches 57. The spring 22 is wound up by inserting the end, e.g. of a screwdriver, in the slot 50 and rotating the adjusting member in an anti-clockwise direction, the plate 56 riding over the teeth 56 and re-engaging as rotation of the adjusting member is stopped. To allow the spring 22 to unwind a screwdriver, with a narrow shank, is inserted into the adjusting member 46 to raise the pawl plate 56 and disengage the teeth 58 from the notches. The spring 22 will unwind until the screwdriver is withdrawn, the spring 61 then urging the teeth 58 to re-engage with the notches 57. The adjusting mechanism is suitable for use with balances having only a torsion spring. As shown, a conventional two-spring spiral sash balance comprises the outer spring 11 and the inner torsion spring 22 which carries at its upper end a slotted nut 26 which follows the spiral of a rod 15 suspended from an eyelet 17 passing through a hanger 10 for the upper end of the spring 11, and receiving, e.g. a nail 20, which secures an outer tubular housing 12 to a jamb 21 of a fixed frame for a window.