Wedge brake elevator safety system

Abstract

A vertical lift system having a safety brake assembly (10) employing a pair of brakes attached to cables running vertically on each side of a guiderail (1). Each brake has a series of wedges (13, 14, and 15), including a braking wedge (14) that presses against the guiderail to brake downward motion of an elevator or lift basket upon an interruption in cable tension. A cable tension adjustment mechanism (3, 4 and 6) to equalize tension in the cables is also incorporated into the safety brake assembly. An electrical sensor (18) is also provided to disrupt power to the lift system upon slackening of a cable.

Claims

1. A vertical lift device with brake assembly comprising: a guiderail having at least two opposite sides; a cable drum for holding a predetermined length of cable mounted over said guiderail, having a minimum of two cables suspended therefrom; at least one cable positioned on opposite sides of the guiderail; and a cable brake attached to an end of each cable to clamp the guiderail in the event of cable failure.

2. The vertical lift device with brake assembly of claim 1 wherein each cable brake comprises: a plurality of wedges comprising an outer stationary wedge, a middle actuating wedge and an inner braking wedge with a braking surface for grippingly engaging a side of the guiderail when the cable brake moves downward along the guiderail.

3. The vertical lift device with brake assembly of claim 2 wherein the plurality of wedges of each cable brake are connected laterally by a retracting spring.

4. The vertical lift device with cable brake assembly of claim 1 wherein each cable brake further comprises: at least one guide wheel to facilitate movement of the brake up and down a side of the guiderail.

5. The vertical lift device with cable brake assembly of claim 1 wherein each cable is attached to each brake by an eye bolt and shank.

6. The vertical lift device with brake assembly of claim 1 wherein the guiderail is an I-beam.

7. The vertical lift device with brake assembly of claim 1 further comprising means for adjusting tensions in the at least one cable, said means comprising: a cable tension adjustment nut rotatably attached to an end of each cable below each cable brake, said cable tension adjustment nut being rotated against a stop and compression spring to adjust and equalize the tension in each cable.

8. The vertical lift device with brake assembly of claim 1 further comprising an electrical sensor that disrupts electrical power to the lift device upon slackening of a cable.

Description

DESCRIPTION OF THE DRAWINGS

(1) In the following detailed description, reference will be made to the attached drawings in which:

(2) FIG. 1 is a bottom end view of an elevator brake assembly of the present invention with an I-beam being utilized as a guiderail;

(3) FIG. 2 is a front perspective view the elevator brake assembly of the present invention showing the cable arrangement and winding drum with I-beam guiderail;

(4) FIG. 3 is a front view of the elevator brake assembly of the present invention and cable attachment assembly of FIG. 2 without the i-beam guiderail;

(5) FIG. 4 is an enlarged sectional view along section A of FIG. 3 of the elevator brake assembly of the present invention;

(6) FIG. 5 is a rear view of the elevator brake assembly of the present invention and cable attachment assembly of FIG. 2 without the I-beam guiderail; and

(7) FIG. 6 is an enlarged sectional view along section B of FIG. 5 of the elevator brake assembly of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

(8) For purposes of describing the preferred embodiment, the terminology used in reference to the numbered components in the drawings is as follows: 1. I-beam guide rail 2. top guide wheels 3. cable tension adjustment nut 4. spring stops 5. set screws 6. retracting springs 7. brake surfaces 8. bottom guide wheels 9. cable drum 10. elevator brake assembly, generally 11. cable 12. eye bolts 13. actuating wedges 14. braking wedges 15. stationary wedges 16. compression springs 17. rear wedge plates 18. electrical sensor/slack cable switch 19. fasteners for wedge plates 20. electrical power wire to 18

(9) Referring to the drawing figures, FIG. 1 illustrates a bottom end view of the elevator brake assembly 10 of the present invention consisting of dual brake assemblies running vertically within an I-beam 1. Each assembly has lower guide wheels 8 which abuts and runs along a front of the I-beam 1 and a top or upper guide wheel 2 which runs along a center rail of the I-beam 1. Each assembly has a brake surface 7 for gripping against the I-beam 1 in case of a cable malfunction to stop an elevator car from falling. Retracting springs 6 maintain the brake surfaces 7 away from the I-beam 1 during normal operation of an elevator. Rotatable cable tension adjustment nuts 3 and spring stops 4 are provided to adjust the cable tension exerted by compression springs 16 (shown in FIGS. 2-6). An electrical sensor with slack cable switch 18 connected to the electrical wire 20 that powers the elevator is provided to detect cable slackening and deactivate electrical power to the elevator upon such an occurrence.

(10) FIG. 2 illustrates a front perspective view of an elevator brake assembly 10 of the present invention as it would appear in operation without an elevator car attached thereto. The brake assemblies 10 are attached within opposite cavities of the I-beam 1 by eyebolts 12 to a cable 11 from a cable drum 9. Each brake assembly 10 is guided along the I-beam 1 by lower guide wheels 8 and top guide wheels 2 (not shown). Other components of the brake assembly 10, such as brake surface 7, compression spring 16, spring stop 4 and cable tensions adjustment nut 3 are also shown. Also, an electrical sensor with slack cable switch 18 connected to the electrical wire 20 that powers the elevator is provided to detect cable slackening and deactivate electrical power to the elevator upon such an occurrence.

(11) FIG. 3 illustrates a front view of the elevator brake assembly 10 of the present invention without an I-beam guide rail. As previously described the dual brake assemblies 10 are suspended from the cable drum by cable 11 and eye bolt brackets 12. Each brake assembly 10 as shown here and in the enlarged view of FIG. 4 consist of a top plate 18 attached to which are three vertical wedges: an outer stationary wedge 15, a middle actuating wedge 13 and an inner braking wedge 14 with braking surface 7. The braking wedge 7 is attached to the stationary wedge 15 with the actuating wedge 13 sandwiched in between by a retracting spring 6. Also, an electrical sensor with slack cable switch 18 connected to the electrical wire 20 that powers the elevator is provided to detect cable slackening and deactivate electrical power to the elevator upon such an occurrence.

(12) FIGS. 5 and 6 illustrate a rear view of the elevator brake assembly 10 shown in FIGS. 3 and 4. The only components shown here which have not been previously illustrated and described are the rear wedge plate 17 and a plurality of fasteners 19, such as rivets or similar items, which hold together the wedges of the elevator brake assembly 10. Also, an electrical sensor with slack cable switch 18 connected to the electrical wire 20 that powers the elevator is provided to detect cable slackening and deactivate electrical power to the elevator upon such an occurrence.

(13) It is to be understood that while preferred embodiments of the invention have been described, it is not to be limited to the specific form or arrangement of parts herein described and shown. It will be apparent to those skilled in the art that various changes may be made without departing from the scope of the invention and the invention is not to be considered limited to what is shown and described in the specification and/or drawings.