Caldwell Manufacturing Company

Robert S Flight

William P Newton

A pulley mount for a window balance system 10 uses a pair of spaced-apart support plates 13 and 14 each having a shoulder rivet 30 with a shaft fitting through a hole 29 in each of support plates 13 and 14. A pair of pulleys 21,23 and 22,24 are mounted on each rivet, with one pulley mounted on the rivet shoulder 32, and another pulley mounted on a flanged bushing 35 around the rivet shaft. A support plate 13 for one pair of pulleys has a hook 12 for connecting to an end of a channel 11 containing the balance system, and a support plate 14 for another pair of pulleys has a coupler 17 connected to a balance spring 15.

Pulley mount for window balance system

A coupler connects end regions of different sizes of coiled tension springs 30 and 40 to components of block and tackle window balance systems 10. Each coupler 15, 20, or 25 has a snug fit within terminal coils 41 of the strongest spring 40 having the smallest inside diameter, and weaker spring 30 with a larger inside diameter has its terminal coils 31 necked down to fit the coupler. The coupler has a notch or opening with an abrupt edge 18, 22, or 28 axially spaced from an end of the coupler so that the notch is at least twice as long as the largest wire diameter used in the coil springs. At least one of the terminal coils of each spring is indented into the notch or opening in the coupler to a depth of more than one-half the wire diameter so that the indented coil interlocks with edge 18, 22, or 28 and keeps the spring from slipping off the coupler.

Spring coupler for block and tackle window balance system

A block and tackle window sash balance system 10 has its friction made adjustable by a friction spring 20 and a cam 30 arranged for pressing spring 20 against a radial face of a pulley 15 in a high friction position and moving the spring clear of the pulley in a low friction position. Cam 30 is preferably accessible with a screwdriver for adjusting friction after the balance is installed in a window.

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Rochester, NY, United States of America

Robert S Flight