GB844612A - Improvements in and relating to brush holder assemblies - Google Patents

Abstract

844,612. Brush holders and brushes for dynamo-electric machines. METROPOLITANVICKERS ELECTRICAL CO. Ltd. Nov. 9, 1956 [Nov. 22, 1955], No. 33462/55. Class 35. An electric brush holder assembly having a flat spiral spring 8 for applying contact pressure to a brush 4 includes an additional member 16 which is parallel to a portion of the outermost convolution of the spring, is fixedly secured to such portion for rotation therewith and has, for relieving the contact pressure by recoiling the spring, a handle 12 extending substantially radially from its convex surface which is parallel to the spring portion. As shown, the member 16 is a metal strip of stainless steel, spring steel or bronze, spot welded at angularly displaced points 21 ... 24 to the spring, and formed with the spring to provide a contact pressure conveying finger 7; the other end 19 of member 16 is bent to form a hook engageable with a pin 10 to retain the finger in its " hold-off " positions. In modifications the hold-off is provided by the finger, the handle, or an extension of a ratchet plate 9 by which the spring pressure can be adjusted. The brush box 1 which can be made from an extruded section has dust slots 13, 14 and an outer wall ended at 15a to limit finger movement; its inner surface is chamfered on one side only at 37 to receive a complementarily chamfered brush, which ensures correct assembly of the latter.