Locking balance shoe and system for a pivotable window

Abstract

Locking balance shoes and balance systems to be incorporated in pivotable double hung windows include, in one embodiment, a pair of retractable tabs that partially extend through openings within an inverted window balance. In one embodiment of the method of installing such a system, an enlarged portion of the balance shoe is inserted into a window jamb and then rotated into position.

Claims

1. A window balance system adapted to be received in a window jamb track, the window balance system comprising: a U-shaped channel defining a plurality of openings, a channel width (W.sub.C), and a channel depth (D.sub.C); a spring connected to a system of pulleys located within the U-shaped channel; a cord with a first cord end and a second cord end, the first cord end connected to and threaded through the system of pulleys, the second cord end connected to a jamb mounting attachment; and a T-shaped balance shoe, wherein the balance shoe comprises: a frame comprising an elongate portion and an enlarged portion, wherein the elongate portion comprises two frame edge surfaces defining an elongate portion width (W.sub.EL) therebetween and a frame front surface and a frame back surface defining an elongate portion depth (D.sub.EL) therebetween, wherein the enlarged portion comprises two outer surfaces defining an enlarged portion width (W.sub.EN) therebetween, a front surface and a back surface defining an enlarged portion depth (D.sub.EN) therebetween, and opposing surfaces defining an enlarged portion length (L.sub.EN) therebetween, wherein the elongate portion depth (D.sub.EL) is substantially the same as the channel depth (D.sub.C) and the elongate portion width (W.sub.EL) is substantially the same as the channel width (W.sub.C), wherein the enlarged portion width (W.sub.EN) is greater than each of the elongate portion depth (D.sub.EL), the elongate portion width (W.sub.EL), the enlarged portion depth (D.sub.EN), the enlarged portion length (L.sub.EN), the channel width (W.sub.C), and the channel depth (D.sub.C),and wherein the elongate portion is received at least partially within the U-shaped channel, and wherein the two outer surfaces of the enlarged portion are adapted to slide within the window jamb track; a cam at least partially disposed within the enlarged portion, wherein the cam is adapted for rotation between a first position and a second position; a locking device in contact with the cam and at least partially disposed within the enlarged portion, the locking device comprising opposed locking surfaces, wherein the locking surfaces are adapted to extend beyond the two outer surfaces of the enlarged portion when the cam is in the first position; and a connecting device for attaching the balance shoe to the U-shaped channel.

2. The balance system of claim 1, wherein the locking surfaces are adapted to retract to locations within the enlarged portion when the cam is in the second position.

3. The balance system of claim 1, wherein the locking surfaces are joined by a spring member.

4. The balance system of claim 1, wherein the cam defines an opening adapted to receive therein a pivot pin.

5. The window balance system of claim 1, wherein the enlarged portion comprises a plastic.

6. The window balance system of claim 5, wherein the elongate portion comprises the plastic.

7. The balance system of claim 1, wherein the elongate portion includes an opening through the two frame edge surfaces of the elongate portion.

8. The balance system of claim 1, wherein the locking surfaces are forced toward the window jamb track when the cam is in the first position.

9. The balance system of claim 8, wherein the locking surfaces are adapted to engage the window jamb track when the cam is in the first position.

10. The balance system of claim 1, wherein the locking device at least partially surrounds the cam.

11. The balance system of claim 1, wherein the cam is in direct contact with the locking device.

12. The window balance system of claim 1, wherein the frame comprises a resilient member for securing the balance shoe to the U-shaped channel.

13. The window balance system of claim 12, wherein the elongate portion comprises the resilient member.

14. The window balance system of claim 13, wherein the resilient member comprises a tab.

15. The balance system of claim 1, wherein the locking device comprises a plate.

16. The balance system of claim 15, wherein the plate is adapted to engage the window jamb track when the cam is in the first position.

17. The window balance system of claim 1, wherein the frame comprises a unitary construction.

18. The window balance system of claim 1, wherein the connecting device comprises a rivet.

19. The window balance system of claim 18, wherein the elongate portion defines at least one opening adapted to mate with the rivet.

20. A window balance system adapted to be received in a window jamb track, the window balance system comprising: a U-shaped channel defining a plurality of openings, a channel width (W.sub.C), and a channel depth (D.sub.C); a spring connected to a system of pulleys located within the U-shaped channel; a cord with a first cord end and a second cord end, the first cord end connected to and threaded through the system of pulleys, the second cord end connected to a jamb mounting attachment; and a T-shaped balance shoe, wherein the balance shoe comprises: a frame comprising an elongate portion and an enlarged portion, wherein the elongate portion comprises two frame edge surfaces defining an elongate portion width (W.sub.EL) therebetween and a frame front surface and a frame back surface defining an elongate portion depth (D.sub.EL) therebetween, wherein the enlarged portion comprises two outer surfaces defining an enlarged portion width (W.sub.EN) therebetween, a front surface and a back surface defining an enlarged portion depth (D.sub.EN) therebetween, and opposing surfaces defining an enlarged portion length (L.sub.EN) therebetween, wherein the elongate portion depth (D.sub.EL) is substantially the same as the channel depth (D.sub.C) and, the elongate portion width (W.sub.EL) is substantially the same as the channel width (W.sub.C), wherein the enlarged portion width (W.sub.EN) is greater than each of the elongate portion depth (D.sub.EL), the elongate portion width (W.sub.EL), the enlarged portion depth (D.sub.EN), the enlarged portion length (L.sub.EN), the channel width (W.sub.C), and the channel depth (D.sub.C), and wherein the elongate portion is received at least partially within the U-shaped channel, and wherein the two outer surfaces of the enlarged portion are adapted to slide within the window jamb track; a cam at least partially disposed within the enlarged portion, wherein the cam is adapted for rotation between a first position and a second position; and a locking device in contact with the cam, the locking device adapted to be forced toward the window jamb track when the cam is in the first position.

21. The balance system of claim 20, the frame further comprising a resilient tab.

22. The balance system of claim 21, wherein the resilient tab is located on the elongate portion.

23. The balance system of claim 20, wherein the elongate portion includes an opening through the two frame edge surfaces of the elongate portion define an opening therebetween.

24. The balance system of claim 23, wherein the opening is adapted to receive a connecting device.

25. The balance system of claim 20, wherein the locking device at least partially surrounds the cam.

26. The balance system of claim 20, wherein the cam defines an opening adapted to receive therein a pivot pin.

27. The balance system of claim 20, wherein the cam is in direct contact with the locking device.

28. A window balance system adapted to be received in a window jamb track, the window balance system comprising: a U-shaped channel defining a plurality of openings, an axis, a channel width (W.sub.C), and a channel depth (D.sub.C); a spring connected to a system of pulleys located within the U-shaped channel; a cord with a first cord end and a second cord end, the first cord end connected to and threaded through the system of pulleys, the second cord end connected to a jamb mounting attachment; a fastener; and a frame comprising: means defined by the frame for receiving the fastener for pivotally connecting the frame to the U-shaped channel; means for securing the frame against rotation relative to the U-shaped channel; an elongate portion comprising two frame edge surfaces defining an elongate portion width (W.sub.EL) therebetween and a frame front surface and a frame back surface defining an elongate portion depth (D.sub.EL) therebetween; and an enlarged portion comprising two outer surfaces defining an enlarged portion width (W.sub.EN) therebetween, a front surface and a back surface defining an enlarged portion depth (D.sub.EN) therebetween, and opposing surfaces defining an enlarged portion length (L.sub.EN) therebetween, wherein the elongate portion depth (D.sub.EL) is substantially the same as the channel depth, the elongate portion width (W.sub.EL) is substantially the same as the channel width (W.sub.C), and wherein the enlarged portion width (W.sub.EN) is greater than each of the elongate portion depth (D.sub.EL), the elongate portion width (W.sub.EL), the enlarged portion depth (D.sub.EN), the enlarged portion length (L.sub.EN), the channel width (W.sub.C), and the channel depth (D.sub.C).

29. The window balance system of claim 28, wherein the two outer surfaces of the enlarged portion of the frame are adapted to slide within the window jamb track.

30. The window balance system of claim 29, further comprising: a cam located within the frame, wherein the cam is adapted for rotation between a first position and a second position; and a locking device in contact with the cam and comprising opposed locking surfaces, wherein the locking surfaces are adapted to extend toward the window jamb track when the window balance system is received in the window jamb track and the cam is in the first position.

31. The window balance system of claim 30, wherein the elongate portion is integral with the frame.

32. The window balance system of claim 31, wherein the frame comprises a balance shoe.

33. The window balance system of claim 28, wherein the securing means comprises at least one tab.

34. The window balance system of claim 33, wherein the at least one tab engages an opening defined by the U-shaped channel when the frame is connected to the U-shaped channel.

35. The window balance system of claim 28, wherein the fastener comprises a rivet.

36. A window balance system adapted to be received in a window jamb track and counterbalance a window sash, the window balance system comprising: a U-shaped channel defining a channel width (W.sub.C) and a channel depth (D.sub.C); a fastener; and a frame pivotally connected to the U-shaped channel, the frame comprising: means defined by the frame for receiving the fastener for pivotally connecting the frame to the U-shaped channel; means for securing the frame against rotation relative to the U-shaped channel; an elongate portion comprising two frame edge surfaces defining an elongate portion width (W.sub.EL) therebetween and a frame front surface and a frame back surface defining an elongate portion depth (D.sub.EL) therebetween; and an enlarged portion comprising two outer surfaces defining an enlarged portion width (W.sub.EN) therebetween, a front surface and a back surface defining an enlarged portion depth (D.sub.EN) therebetween, and opposing surfaces defining an enlarged portion length (L.sub.EN) therebetween, wherein the elongate portion depth (D.sub.EL) is substantially the same as the channel depth, the elongate portion width (W.sub.EL) is substantially the same as the channel width (W.sub.C), and wherein the enlarged portion width (W.sub.EN) is greater than each of the elongate portion depth (D.sub.EL), the elongate portion width (W.sub.EL), the enlarged portion depth (D.sub.EN), the enlarged portion length (L.sub.EN), the channel width (W.sub.C), and the channel depth (D.sub.C).

37. The window balance system of claim 36, further comprising: a cam substantially located within the frame, wherein the cam is adapted for rotation between a first position and a second position; and a locking device in contact with the cam and comprising opposed locking surfaces, wherein the locking surfaces are adapted to extend toward the window jamb track when the window balance system is received in the window jamb track and the cam is in the first position.

38. The window balance system of claim 36, wherein the elongate portion is received within the U-shaped channel.

39. The window balance system of claim 38, wherein the frame comprises a plastic.

40. The window balance system of claim 38, wherein the elongate portion comprises a plastic.

41. The window balance system of claim 38, wherein the means for securing the frame against rotation comprises a resilient member.

42. The window balance system of claim 41, wherein the resilient member comprises a tab.

43. The window balance system of claim 38, wherein the elongate portion defines the receiving means.

44. A window balance system adapted to be received in a window jamb track, the window balance system comprising: a U-shaped channel defining an axis, a channel width (W.sub.C), and a channel depth (D.sub.C); a spring connected to a system of pulleys located within the U-shaped channel; a cord comprising a first cord end and a second cord end, the first cord end connected to and threaded through the system of pulleys, the second cord end connected to a jamb mounting attachment; a fastener; and a frame comprising: means defined by the frame for receiving the fastener for pivotally connecting the frame to the U-shaped channel; means for securing the frame against rotation relative to the U-shaped channel, an elongate portion comprising two frame edge surfaces defining an elongate portion width (W.sub.EL) therebetween and a frame front surface and a frame back surface defining an elongate portion depth (D.sub.EL) therebetween; and an enlarged portion comprising two outer surfaces defining an enlarged portion width (W.sub.EN) therebetween, a front surface and a back surface defining an enlarged portion depth (D.sub.EN) therebetween, and opposing surfaces defining an enlarged portion length (L.sub.EN) therebetween, wherein the elongate portion depth (D.sub.EL) is substantially the same as the channel depth, the elongate portion width (W.sub.EL) is subtantially the same as the channel width (W.sub.C), wherein the enlarged portion width (W.sub.EN) is greater than each of the elongate portion depth (D.sub.EL), the elongate portion width (W.sub.EL), the enlarged portion depth (D.sub.EN), the enlarged portion length (L.sub.EN), the channel width (W.sub.C), and the channel depth (D.sub.C), and wherein the U-shaped channel and the frame are T-shaped when connected.

45. The window balance system of claim 44, wherein the frame further comprises: a cam located within the frame, wherein the cam is adapted for rotation between a first position and a second position; and a locking device in contact with the cam and comprising opposed locking surfaces, wherein the locking surfaces are adapted to extend substantially orthogonal to the axis toward the window jamb track when the window balance system is received in the window jamb track and the cam is in the first position.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In the drawings, like reference characters generally refer to the same parts throughout the different views. Also, the drawings are not necessarily to scale, emphasis instead generally being placed upon illustrating the principles of the invention.

(2) FIG. 1 is a perspective view of a pivotable double hung window assembly;

(3) FIG. 2A is a rear view of inverted window balance system for use with a prior art balance shoe;

(4) FIG. 2B is a rear view of a window balance;

(5) FIG. 3A is one perspective view of an embodiment of a snap lock balance shoe of the present invention;

(6) FIG. 3B is another perspective view of the embodiment of the snap lock balance shoe of FIG. 3A;

(7) FIG. 3C is a rear view of one embodiment of a snap lock inverted balance system;

(8) FIG. 3D is a bottom view of one embodiment of a snap lock balance shoe;

(9) FIG. 3E is a front view of one embodiment of a snap lock balance shoe;

(10) FIG. 3F is a side view of one embodiment of a snap lock balance shoe;

(11) FIG. 4 is a perspective view of an embodiment of a snap lock balance shoe of the present invention;

(12) FIG. 5A is one perspective view of another embodiment of a snap lock balance shoe of the present invention;

(13) FIG. 5B is another perspective view of the embodiment of the snap lock balance shoe of FIG. 5A;

(14) FIG. 6A is a perspective view of one embodiment of a balance shoe of the invention and a rigid U-shaped channel;

(15) FIG. 6B is a perspective view showing the first step of connecting one embodiment of the balance shoe of the invention to the rigid U-shaped channel;

(16) FIG. 6C is a perspective view showing the second step of connecting one embodiment of the balance shoe of the invention to the rigid U-shaped channel;

(17) FIG. 6D is a perspective view showing one embodiment of the balance shoe of the invention connected to the rigid U-shaped channel;

(18) FIG. 7A is a front view of a prior art balance shoe attached to a rigid U-shaped channel;

(19) FIG. 7B is a side view of the prior art balance shoe attached to the rigid U-shaped channel;

(20) FIG. 8A is a front view of one embodiment of a snap lock balance shoe of the present invention attached to a rigid U-shaped channel;

(21) FIG. 8B is a side view of one embodiment of the snap lock balance shoe of the present invention attached to the rigid U-shaped channel;

(22) FIG. 9 is a front view of a window assembly including one snap lock inverted window balance system of the present invention and one prior art inverted window balance system installed in a window frame;

(23) FIG. 10A is a side view illustrating the first step of installing the snap lock inverted window balance system of the invention into the jamb track;

(24) FIG. 10B is a front view illustrating the first step of installing the snap lock inverted window balance system of the invention into the jamb track;

(25) FIG. 11A is a side view illustrating the second step of installing the snap lock inverted window balance system of the invention into the jamb track;

(26) FIG. 11B is a front view illustrating the second step of installing the snap lock inverted window balance system of the invention into the jamb track;

(27) FIG. 12A is a side view illustrating the third step of installing the snap lock inverted window balance system of the invention into the jamb track;

(28) FIG. 12B is a front view illustrating the third step of installing the snap lock inverted window balance system of the invention into the jamb track;

(29) FIG. 13A is a side view illustrating the last step of installing the snap lock inverted window balance system of the invention into the jamb track; and

(30) FIG. 13B is a front view illustrating the last step of installing the snap lock inverted window balance system of the invention into the jamb track.

DETAILED DESCRIPTION OF THE INVENTION

(31) Referring to FIG. 1, shown is a pivotable double hung window assembly 100 in which a snap lock balance shoe constructed in accordance with the teachings of the present invention can be used. The pivotable double hung window assembly 100 includes of a window frame 102, a pivotable lower window sash 104, a pivotable upper window sash 106, and a window jamb 107. The pivotable lower window sash 104 and the pivotable upper window sash 106 slide vertically in jamb track 108 within the window jamb 107, while also being able to pivot about a pivot bar 114, as shown in FIG. 9.

(32) FIG. 2A shows a rear view of an inverted window balance system 120 for use in the pivotable double hung window assembly 100. The inverted window balance system 120 includes an inverted window balance 122 used for balancing the weight of either the pivotable lower window sash 104 or the pivotable upper window sash 106 at any vertical position within the window frame 102, and a prior art balance shoe 110 for guiding the rotation of the pivotable lower window sash 104 about the pivot bar 114. A hanging connector 112 connects the prior art balance shoe 110 to the inverted window balance122. The inverted window balance 122 includes an extension spring 126 connected to a system of pulleys 128 housed within a rigid U-shaped channel 130 having a width (W.sub.C) and a depth (D.sub.C) (see FIGS. 8A and 8B), and a cord 132 for connecting the system of pulleys 128 to a jamb mounting attachment 134. The jamb mounting attachment 134 is used for connecting the inverted window balance system 120 to the window jamb 107. One difference between the inverted window balance 122 and a window balance 140, shown in FIG. 2B, includes the placement of the extension spring 146 above a system of pulleys 148 within the rigid U-shaped channel 150. A cord 152connects the system of pulleys 148 to a jamb mounting attachment 154. Another difference is that while inverted window balances 122 travel with either the pivotable lower window sash 104 or pivotable upper window sash 106, the window balance 140 remains in a fixed position in the window jamb 107 due to an attachment to the window jamb 107 through an attachment opening 155.

(33) FIGS. 3A and 3B are perspective views of a snap lock balance shoe 210 of one embodiment of the present invention. The snap lock balance shoe 210 has a frame 211 in which is housed a connecting device 212, a locking device 214, and a cam 218. The connecting device 212 can be integral with the frame 211 and attaches the snap lock balance shoe 210 directly within an inverted window balance 622, shown in FIG. 3C. The inverted window balance 622 in combination with the snap lock balance shoe 210 forms a snap lock inverted window balance system 600. The inverted window balance 622 includes an extension spring 626 connected to a system of pulleys 628 housed within a rigid U-shaped channel 630, and a cord 632 for connecting the system of pulleys 628 to a jamb mounting attachment 634, such as a cord terminal or hook.

(34) In the depicted embodiment, the connecting device 212 is a pair of retractable tabs that snap into the rigid U-shaped channel 630. In other embodiments, other connecting devices such as a screw, may be used to secure the frame 211 to the rigid U-shaped channel 630. A fastener 635 located in the inverted window balance 622 can be used to further secure the connection between the snap lock balance shoe 210 and the inverted window balance 622. To accommodate the fastener 635, the snap lock balance shoe 210 can form a connection pocket 213 sized to receive or mate with the fastener 635.

(35) Another element of the snap lock balance shoe 210 visible in FIG. 3A is a keyhole opening 219 located within the cam 218. The keyhole opening 219 is sized to accept the pivot bar 114 extending from either the pivotable lower window sash 104 or the pivotable upper window sash 106, and serves as a connection point between the pivotable lower or upper window sash 104, 106 and the snap lock balance shoe 210. FIG. 3B shows a perspective view of the snap lock balance shoe 210 showing another face of the cam 218.

(36) In the embodiment shown in FIG. 3B, the locking device 214 surrounds the cam 218 and includes of a pair of opposing ends 215 connected by a spring member 216. When the pivotable lower window sash 104 is tilted open, the pivot bar 114 rotates, which in turn rotates the cam 218 forcing the opposing ends 215 outward to engage the jamb track 108 of the window frame 102, thereby locking the balance shoe 210 in that location.

(37) FIGS. 3D-3F show different views of one of the embodiments of the snap lock balance shoe 210 of the invention. FIG. 3D is a bottom view of the snap lock balance shoe 210 that shows a frame bottom surface 230. FIG. 3E is a front view of the same embodiment of the snap lock balance shoe 210 that illustrates a frame front surface 240 and with a frame back surface defining a depth (D.sub.EL) therebetween (see FIG. 3F), and FIG. 3F is a side view that shows one of the two frame edge surfaces 250 of the snap lock balance shoe 210 which together form a width (WEL) therebetween (see FIG. 3E). As shown in FIGS. 3E and 3F, the snap lock balance shoe 210 is substantially T-shaped and includes an elongate portion 252 and an enlarged portion 254. Outer surfaces 256 and 258 define a width (W.sub.EN) of the enlarged portion 254. A front surface 260 and a back surface 262 define a depth (D.sub.EN) of the enlarged portion 254. Opposing surfaces 264 and 266 define a length (L.sub.EN) of the enlarged portion 254. Referring to FIGS. 3E, 3F, 8A, and 8B, the elongate portion depth (D.sub.EL), the elongate portion width (W.sub.EL), the enlarged portion depth (D.sub.EN), the enlarged portion length (L.sub.EN), the channel width (W.sub.C), and the channel depth (D.sub.C) are similarly dimensioned. Also, the enlarged portion width (W.sub.EN) is substantially greater than the elongate portion depth (D.sub.EL), the elongate portion width (W.sub.EL), the enlarged portion depth (D.sub.EN), the enlarged portion length (L.sub.EN), the channel width (W.sub.C), and the channel depth (D.sub.C).

(38) FIG. 4 shows another embodiment of a snap lock balance shoe 310. The snap lock balance shoe 310 has an elongated frame 311 in which is housed a collecting device 312, a locking device 314, and a cam 318. Within the cam is a keyhole opening 319 sized to receive the pivot bar 114. The elongated frame 311 has a length L 325 that is greater than about 1.25 inches. When attached to the rigid U-shaped channel 630, the balance shoe 310 extends further outward from the rigid U-shaped channel 630 than the balance shoe 210 attached to a similar sized rigid U-shaped channel 630. The balance shoe 310 allows a fixed-sized rigid U-shaped channel 630 to be used in a larger window having a greater travel distance by extending the length of the entire window balance system by having a longer balance shoe 310. One of the advantages of the present invention is that an installer can create a custom window balance system for a particular window by fitting a fixed-length rigid U-shaped channel 630 with an appropriately sized snap lock balance shoe.

(39) Referring to FIGS. 5A-5B, shown is another embodiment of the present invention of a snap lock balance shoe 410. The snap lock balance shoe 410 has a locking member 422 which engages a back wall of the jamb track 108 locking the balance shoe 410 in that location. The locking member 422 is partially disposed in the frame 411 and includes a plate 423 that engages the back wall of the jamb track 108. The balance shoe 410 also includes a frame 411, a connecting device 412, and a cam 418. The cam 418 is partially disposed within the frame 411 in a space enclosed by the locking member 422. The cam 418 includes a keyhole opening 419 sized to receive the pivot bar 114. Upon rotation of the cam 418 with the pivot bar 114, the locking member 422 is forced away from the frame 411 towards the back wall of the jamb track 108, thereby anchoring the balance shoe 410 in that location within the window frame 102.

(40) FIGS. 6A-6D show one embodiment of a method for securing the snap lock balance shoe 210 within a rigid U-shaped channel 630 with multiple openings 638. It should be noted that each opening 638 on one side of the rigid U-shaped channel 630 has a corresponding opening 638 on the other side of the rigid U-shaped channel 630 to form a pair of openings. The first step, shown in FIG. 6A, is to place a fastener 635, such as a rivet, in one of the pairs of openings 638 in the rigid U-shaped channel 630. The next step, as depicted in FIG. 6B, is to slide the snap lock balance shoe 210 into the rigid U-shaped shaped channel 630 such that the fastener 635 is received in the connection pocket 213 of the snap lock balance shoe 210. As shown in FIG. 6C, the snap lock balance shoe 210 is then rotated down so that the front frame surface 240 is aligned with a bottom wall 636 of the rigid U-shaped channel 630. FIG. 6D shows the last step of attaching the snap lock balance shoe 210 within the rigid U-shaped channel 630. In this step, the connecting device 212 of the snap lock balance shoe 210 snaps into one of the pairs of openings 638 located on the rigid U-shaped channel 630. In alternative embodiments the connection device 212 of the snap lock balance shoe 210 can extend through off-set openings in the rigid U-shaped channel 630. In some embodiments, the snap lock balance shoe 210 is attached to the rigid U-shaped channel 630 with the fastener 635. In other embodiments, the snap lock balance shoe 210 is attached to the rigid U-shaped channel 630 without the fastener 635. It should also be noted that in some embodiments, the snap lock balance shoe 210 can be aligned and secured to the rigid U-shaped channel 630 such that the front frame surface 240 faces upwards instead of downwards as depicted in FIG. 6D.

(41) FIG. 7A is a front view of the prior art balance shoe 110 attached to the rigid U-shaped channel 130. The rigid U-shaped channel 130 is connected to the prior art balance shoe 110 by the hanging connector 112. No part of the prior art balance shoe 110 lies within the rigid U-shaped channel 130. FIG. 7B is a side view of the prior art balance shoe 110 attached to the rigid U-shaped channel 130 illustrating channel openings 137. Fasteners (not shown) are installed through the channel openings 137 to secure the hanging connector 112 to the rigid U-shaped channel 130.

(42) Referring to FIGS. 8A and 8B, shown is an embodiment of the snap lock balance shoe 210 of the present invention attached to the rigid U-shaped channel 630. The snap lock balance shoe 210 is directly attached within the rigid U-shaped channel 630 by a connecting device 212 located on the frame 211 of the snap lock balance shoe 210. The connecting device 212 extends through a pair of openings 638 located on the rigid U-shaped channel 630.

(43) FIG. 9 is a front view of a pivotable double hung window assembly 800 in which an inverted window balance 122 is attached to a prior art balance shoe 110 by using the hanging connector 112, and the inverted window balance 622 is attached to the snap lock balance shoe 210 of an embodiment of the present invention. Pivot bars 114, as shown in FIG. 9, are secured to the pivotable lower window sash 104. The pivot bars 114 are slidably receivable by both the prior art balance shoe 110 and the snap lock balance shoe 210 and serve as connections between the pivotable lower window sash 104 and respective inverted window balances 122, 622.

(44) An advantage of the type of balance shoe presently disclosed is that the snap lock balance shoe 210 is attached within the rigid U-shaped channel 630 resulting in a longer rigid U-shaped channel 630 than in the inverted balance systems 120 for a given window sash. The longer rigid U-shaped channel 630 of the inverted window balance 622 allows for the use of longer extension springs that provide greater control of the vertical positioning of the window sash than a shorter rigid U-shaped channel 130 with a shorter extension spring. Another advantage of the present invention is that the snap lock balance shoe 210 contains a smaller number of parts than prior art balance shoes 110.

(45) One installation method used to place a snap lock inverted window balance system 600 within the jamb tracks 108 is schematically illustrated in the remaining figures. The snap lock inverted window balance system 600 includes one inverted window balance 622 and one snap lock window balance 210. FIGS. 10A, 11A, 12A, and 13A show the installation method from a side view, while FIGS. 10B, 11B, 12B, and 13B show the method from a front view. The installation method involves an orientation step, a first rotation step, and a second rotation step. FIGS. 10A and 10B show the orientation step in the installation method. In the orientation step, the snap lock inverted window balance system 600 is inserted the jamb tracks 108 such that an axis CC 510 in FIG. 10A is perpendicular to a back wall 530 of the jamb tracks 108, while an axis DD 520 in FIG. 10A is parallel to the back wall 530 and the frame front surface 240 is adjacent to a side wall 532 of the jamb tracks 108. FIGS. 11A and 11B show the snap lock inverted window balance system 600 inserted in the jamb tracks 108 as well as an arrow 550 indicating the direction of rotation of the snap lock inverted window balance system 600 required to complete the first rotation step. The first rotation step involves rotating the snap lock inverted window balance system 600 90-degrees about the axis CC 510 such that the frame front surface 240 faces downward. FIGS. 12A and 12B show the snap lock inverted window balance system 600 after the 90-degree rotation around the axis CC 510 has been completed. The second rotation step involves a 90-degree rotation about the axis DD 520. An arrow 560 showing the direction of the second rotation step is shown in FIGS. 12A and 12B. FIGS. 13A and 13B show in two different views the snap lock inverted window balance system 600 after the installation method has been completed. The cord terminal or any other jamb mounting attachment 634 (see FIG. 9) can then be screwed or hooked into place to anchor the snap lock inverted window balance system 600.

(46) The installation method just described can be carried out in reverse to remove the snap lock inverted window balance system 600 from the jamb track 108 of the window frame 102 to allow for easy replacement of the snap lock balance shoe 210 or the snap lock inverted window balance system 600 itself. In order to replace inverted window balance systems 120 with prior art balance shoes 110, either the jamb tracks 108 need to be warped or completely removed in order to replace the prior art balance shoe 110 of the inverted window balance system 120.

(47) While there have been described several embodiments of the invention, other variants and alternatives will be obvious to those skilled in the art. Accordingly, the scope of the invention is not limited to the specific embodiments shown.