US3799296A

US3799296A - Cable drum brake

Info

Publication number: US3799296A
Application number: US00325869A
Authority: US
Inventors: R Lester
Original assignee: Celotex Corp
Current assignee: WAYNE-DALTON CORP AN OH CORP; Celotex Corp
Priority date: 1973-01-22
Filing date: 1973-01-22
Publication date: 1974-03-26
Anticipated expiration: 1991-03-26
Also published as: CA998627A

Abstract

In a side coiling door having cables to pull the door through its closing movement, a brake to exert a selected extent of opposition against unwinding rotation of the cable drum so that the upper cable spanning across the upper edge of the door opening does not sag down into the opening under its own weight causing a snagging hazard or the like, and which brake, however, does not impede or otherwise interfere with the wind-up directional rotation of the cable drum. Moreover, the functioning of the brake which contemplates a jamming together of parts to produce the resistance or opposition to rotation is used to advantage by having said brake mounted on a multi-position spring, so that a selected spring position produces a corresponding spring urgency or bias which determines the braking force produced during said jamming.

Description

nited States Patent 1 [111 3,799,%

Lester Mar. 26, 11974 1 CABLE DRUM BRAKE Inventor: Russell H. Lester, Commack, NY.

Assignee: The Celotex Corporation, Tampa,

Fla.

Filed: Jan. 22, 1973 Appl. No.: 325,869

US. Cl 188/82.8, 188/134, 242/156.2 lint. Cl. Fl6d 65/06 Field of Search 188/828, 82.84, 134, 136,

References Cited UNITED STATES PATENTS Primary Examiner-Duane E. Reger Attorney, Agent, or Firm-James W. Grace [5 7] ABSTRACT In a side coiling door having cables to pull the door through its closing movement, a brake to exert a selected extent of opposition against unwinding rotation of the cable drum so that the upper cable spanning across the upper edge of the door opening does not sag down into the opening under its own weight causing a snagging hazard or the like, and which brake, however, does not impede or otherwise interfere with the wind-up directional rotation of the cable drum, Moreover, the functioning of the brake which contemplates a jamming together of parts to produce the resistance or opposition to rotation is used to advantage by having said brake mounted on-a multi-position spring, so that a selected spring position produces a corresponding spring urgency or bias which determines the braking force produced during said jamming.

6 Claims, 41 Drawing Figures CABLE DRUM BRAKE The present invention relates generally to an improved brake for a shaft or other rotating operative part, and more particularly to an improved brake or rotation control for a cable drum of a side coiling door.

As generally understood, a side coiling door is pulled by cables through its closing movement and urged through its opening movement by being helically wound about a vertically oriented support shaft or drum, the cables during said door opening movement being unwound from a drum, reel, or the like. With a large door opening in particular, the spanning upper cable, unless restrained from doing so, will sag under its own weight into the door opening and in such position represents a snagging hazard. Various expedients are thus used to pay out the cable under controlled conditions, but none function with complete satisfaction. Such devices invariably are complicated because of the need to oppose rotation in one direction, but not in the other; yet the normal abuse occasioned by the frequent opening and closing of the door is of such an extent as to soon cause malfunctioning in such complicated mechanical devices. Further, none of the known devices are readily adjustable in the extent or degree of drag that they can be made to exert in opposition to unwinding cable drum rotation.

Broadly, it is an object of the present invention to provide an improved side coiling door cable drum brake overcoming the foregoing and other shortcomings of the prior art. Specifically, it is an object to provide a sturdy brake of simple construction which automatically performs a braking or non-braking function in response to the directional rotation of the cable drum, and thus is readily operatively arranged to brake only in the cable-unwinding directional rotation thereof.

A cable drum brake demonstrating objects and advantages of the present invention includes a brake shoe disposed in braking relation to said cable drum and slidable from a clearance non-breaking position into a braking zone of a progressively diminishing volume until attaining a braking position which opposes rotation by jamming. Said braking position, however, is not determined by the wedging of the shoe to the extent in which there is a complete stoppage in rotation, as characterized by the prior art, but rather is determined by limiting the sliding movement of said brake shoe to an operative position from which drag pressure is advantageously exerted which merely slows rotation. Moreover, this operative position is adjustable so that the ultimate pressure or braking force that is exerted to oppose rotation is correspondingly adjustable.

The above brief description, as well as further objects, features and advantages of the present invention, will be more fully appreciated by reference to the following detailed description of a presently preferred, but nonetheless illustrative embodiment in accordance with the present invention, when taken in conjunction with the accompanying drawings, wherein:

FIG. 1 is an isometric view illustrating the environment in which use is advantageously made of a brake according to the present invention;

FIG. 2 is an isometric view, on an enlarged scale, illustrating details of the construction of the brake; and

FIGS. 3a and 3b are related side elevational views, FIG. 3a illustrating the position of the parts of the brake when it is opposing rotation, and FIG. 3b illustrating the position of said parts when it is not so opposing rotation.

Reference is now made to the drawings and in particular to FIG. 1 wherein there is shown a side coiling door, generally designated 10, which will be understood to have a conventional drive arrangement i2 operated by a motor 14 to urge the door through its opening and closing movements relative to a door opening 16 of a building 18. As is generally understood,

cables

20 and 22 are connected to the front edge of the door and are used to pull the door through its closing movement, the

cables

20, 22 at this time being wound about a cable drum 24 which is powered in rotation in the direction 26 by the motor 14. Specifically, motor M is operated so that the shaft 27 thereof rotates in the direction 26 and is thus effective in transmitting via the pulley belt arrangement 28 the rotation of drive shaft 30 also in the direction 26, which direction will be understood to be the drive direction of a clutch 32, thus causing corresponding drive movement 26 in the pulley belt 34 which results in the previously noted wind-up directional movement 26 in the drum 24.

Since the aforesaid directional rotation 26 of the drive shaft 30 corresponds to the slip direction 36 of the clutch 38, there is no power transmitted at this time via the pulley 40, and thus the door support shaft 42 is free wheeling, or unimpeded in that direction of rotation which results in unwinding of the door 10 from about the shaft 42. Further, as laready noted, since the

cables

20 and 22 are pulling the door it) through its closing movement, these cables are taut and there, therefore, is no particular problem involved in the handling of these cables.

When the door 10 is urged through its opening movement 441, however, there could be a problem in the handling of the upper cable 20 in that this cable must not be permitted to sag into the position illustrated in phantom perspective in FIG. 1, since this sagging position is unsightly and, more important, could result in snagging of objects being transported through the opening E6.

The potential snagging condition of the upper cable 20 arises as follows. To achieve opening movement 44 in the door 10, motor 14 is operated so that the shaft 27 thereof is powered through directional movement 26. This produces corresponding rotation 36, via the pulley 2%, in the drive shaft 30 and this directional rotation will be understood to correspond to the drive direction of clutch 38 and also the slip direction of clutch 32. Thus, at this time, pulley 40 is functional and pulley 34 is not functional, with the result that the door shaft 42 is urged through its wind-up direction 44 while the drum 24 is theoretically free wheeling since it is not being restrained or in any other way affected by operation of the pulley 34. At this time, unless there is opposition exerted against the rotation of the drum 2%, the sheer weight of the upper cable 20, particularly when it is of a length which spans across a large door opening 16, will thus result in inadvertent sagging thereof. In accordance with the present invention, this contingency is minimized by a brake means, generally designated 50, in the operation of which it is readily possible to exert any selected extent of opposition against unwinding rotation 46 in the drum 24 while at the same time not interfering or impeding with opposite rotational movement 36 in the drum.

The structural details of a preferred embodiment of the brake means 50 hereof is illustrated in FIG. 2, while the functioning thereof in response to the opposite rtational directions 36 and 46 of the cable drum 24 is illustrated in FIGS. 3a and 3b. Having reference to these figures in conjunction with FIG. 1, it will be noted that the brake 50 includes a shaft member 52 which is fixedly mounted on the cable drum shaft 54 so as to be rotatable therewith, member 52 having an annular friction surface 56. Disposed in facing relation to surface 56 is a similarly curved friction surface 58 of a brake shoe 60 which is operatively arranged so that the

friction surfaces

56, 58 are in contact with each other. However, when this contact is under light pressure, brake shoe 60 does not impede or significantly oppose rotation of member 52, and thus rotation of shaft 54 and of drum 24 mounted thereon, but when the aforesaid contact between the

surfaces

56, 58 is under heavy pressure, then, of course, a significant braking function is performed by the brake shoe 60 in that the same opposes rotation of the shaft member 52.

Brake shoe 60 is operatively arranged for reciprocating sliding movement relative to shaft member 52 on a track arrangement, generally designated 62, which in a preferred embodiment as illustrated herein consists of two cooperating

track members

64 and 66 and a jamming member 68, the function and operation of all of which will now be explained. Specifically, track member 64 is appropriately fixed as a base member to the body of the brake shoe 60 and has a notch 70 therein bounded by

opposite sides

72 and 74 which function as stops or end limits for rolling movement of the jamming member 68, notch 70 being disposed in facing relation to the member 68. The other track member 66 has a notch 76 facing in the opposite direction and which is bounded by

sides

78 and 80 which also function as stops or end limits for rolling movement of the jamming member 68 which is disposed in spanning relation across the two

notches

70 and 76. Enlarged

diameter members

82 and 84 formed on opposite ends of the cylindrical body 68 maintain this body in its rolling relation within the

notches

70 and 76 by preventing any shifting laterally of the rolling direction movement of the member 68.

The manner in which the sides of the

notches

70 and 76 limit rolling movement of the jamming member 68 and, in so doing, achieve a braking function only in the directional rotation 46 of the cable drum 24 while permitting unimpeded rotation in the opposite direction 36, can be best appreciated by reference to FIGS. 3a and 3b. Specifically, as illustrated in FIG. 3b, in response to rotation of shaft member 52 in the direction 36, brake shoe 60 is urged through sliding movement to the right, as viewed in FIG. 3b, until it reaches its furthest position of movement in that direction. This is determined by contact of jamming member 68 against stop 80 of track member 66 and by stop 72 of track member 64 contacting the opposite side of jamming member 68 and thereby preventing any further sliding movement of brake shoe 60. This is the non-braking position of member 68 and the position in which it is located its furthest distance from the center of shaft member 52, this distance being represented by the reference line 86.

In contrast to the foregoing, when member 52 is rotated in the opposite direction 46, brake shoe 60 slides to the left, as viewed in FIG. 3a, in response to this directional movement. Such sliding movement of the brake shoe 60 occurs until jamming member 68 encounters stop 78 of track member 66 and stop 74 of track member 64 engages the opposite side of the jamming member 68. This is the braking position of member 68, being that in which it jams the brake shoe 60 under sufficient pressure against the shaft member 52 to achieve a braking function, i.e., when shoe 60 exerts a desired extent of opposition against rotation of the shaft member 52 in the direction 46. In the FIG. 3a braking position of member 68, it occupies a position which is closest to the center of the shaft member 52, this distance being represented by the reference line 88.

From the preceding description, it should be obvious that the rolling path of movement of the jamming member 68 between the stationary track member 66 and the sliding track member 64, which is part of the brake shoe 60, is along a line segment which completes a triangle in which reference line 88 is the other side thereof and reference line 86 is the hypotenuse. The

jamming or braking effect produced by cylindrical member 68 in its FIG. 3a position, as compared with its non-braking position of movement illustrated in FIG. 3b, is thus demonstrated by the size difference between the side and the hypotenuse of the previously noted triangle. Stated another way, the track member 66 is disposed in facing relation to the shaft member 52 so as to define a clearance space therebetween of a progressively diminishing volume in the sliding direction of brake shoe 60 corresponding to rotational movement 46. Thus, sliding movement of the brake shoe 60 into the diminished volume of the clearance space necessarily must result in a jamming of the brake shoe 60 against the shaft member 52 and, consequently, in the pressing together of the friction surfaces 56, 58 of these members under a sufficient extent of pressure which results in a braking function or in the application of a drag against rotation of the shaft member 52 in the rotational direction 46.

Not only is the brake means 50 effective in exerting opposition to rotation only in one direction, i.e., rotational direction 46, but it is also a significant aspect of its functioning that the extent of opposition which it exerts is readily adjustable. To this end, the stationarily mounted track member 66 of the brake 50 is disposed in a clearance position relative to a support wall or structure 90 by being mounted on a spring body 92, one end of which is fixedly connected in any appropriate manner to a spacing block 94, and the other end of which is free to be urged through adjusting movement 96 toward or away from the support 90. As illustrated, a simple expedient that will permit an adjusting movement 96 and then enable holding the movable end of the spring 92 in any selected position of movement is achieved using a threaded stud 98 which is projected through an oversized hole in the end of the spring 92 and then engaging this spring end on opposite sides by

threadable members

100, 102. Thus, to increase the pressure exerted by the brake shoe 60 in opposing rotation 46 of the shaft member 52, it is necessary only to raise the

nuts

100 and 102 along the threaded stud 98 thereby flexing member 92, which will be understood to be fabricated of a spring or resilient metal or the like, toward the shaft member 52. This increases the force urgency being exerted by the spring body 92 in the direction of the shaft member 52. Thus, when the cylindrical jamming member 68 partakes of rolling movement to the left, as viewed in FIG. 3a, this greater urv gency or biasing force being exerted by the spring body 92 in the direction of the shaft member 52 is transmitted through the member 68 and brake shoe 60 and results in a corresponding increase in the pressure under which the friction surfaces 56 and 58 engage each other. Naturally, to reduce the braking effect or drag that the brake shoe 60 has on the shaft member 52, it is necessary only to lower the

nuts

100 and 102 along the threaded stud 98 and in this way increase the jamming distance 88 so that the jamming produced by the member 68 in its jamming or braking position, as illustrated in FIG. 3a, is less severe.

A latitude of modification, change and substitution is intended in the foregoing disclosure and in some instances some features of the invention will be employed without a corresponding use of other features. Accordingly, it is appropriate that the appended claims be construed broadly and in a manner consistent with the spirit and scope of the invention herein.

What is claimed is:

1. In combination, a shaft operatively arranged for selective rotation in either a clockwise or a counterclockwise direction of rotation, a shaft member fixedly mounted on said shaft having an external cylindrical friction surface, and a brake means for exerting a selected extent of opposition against said shaft rotation in only one said direction of rotation comprising means defining a track located in a clearance position from said shaft member and in facing relation thereto so as to define a triangular clearance space therebetween of a progressively diminishing volume, a brake shoe disposed in an interposed position for reciprocating sliding movement on said track with a cooperating cylindrical friction surface thereof in contacting relation with said friction surface of said shaft member, a cylindrical jamming member disposed in rolling relation to said track and said brake shoe movable in response to the sliding directional movement of said brake shoe in the direction of said diminishing volume of said clearance space from a non-braking position of movement along a path of movement defined by said track into a braking position jamming said brake shoe into braking relation with said shaft member, and a spring operatively arranged to exert a selected extent of urgency mounted in supporting relation to said track, whereby braking opposition is exerted by said braking shoe against said shaft member only in said braking position of said jamming member and in an extent related to the urgency selected for said spring.

2. The combination as defined in claim 1 wherein said spring is a planar body operatively mounted adjacent one end to a support and having its opposite end selectively positionable with respect to said support, and wherein said track is supportingly mounted on said planar body.

3. The combination as defined in claim 2 wherein said track includes a cooperating pair of members disposed in facing relation to each other, each said member having a notch for accommodating said jamming member in interposed position therebetween, and wherein the sides bounding said notches effectively serve as limits for the rolling movement of said jamming member.

4. In combination, a member operatively arranged for selective rotation in either a clockwise or counterclockwise direction of rotation having an external cylindrical friction surface, and a brake means for exerting a selected extent of opposition against said member in only one said direction of rotation comprising a pair of facing track members defining a track located in a clearance position from said member so as to define a triangular clearance space therebetween of a progressively diminishing volume, a brake shoe disposed in an interposed position for reciprocating sliding movement on one said track member with a cooperating cylindrical friction surfacethereof in contacting relation with said friction surface of said member, and a cylindrical jamming member disposed in rolling relation between said track members so as to be movable in response to the sliding directional movement of said brake shoe in the direction of said diminishing volume of said clearance space from a non-braking position of movement along a path of movement defined by said track member into a braking position jamming said brake shoe into braking relation with said member, whereby braking opposition is exerted by said braking shoe against said shaft member only in said braking position of said jamming member.

5. The combination, as claimed in claim 4 including a spring having a planar body operatively arranged in supporting relation to said pair of track members such that one end ofsaid spring body is adapted to be adjusted in position to correspondingly adjust the position of said brake shoe relative to said member, to thereby permit regulation of the extent of opposition being exerted by said brake shoe against rotation of said member.

6. The combination as defined in claim 5 wherein each said track member has a notch for accommodating said jamming member in interposed position therebetween, and wherein the sides bounding said notches effectively serve as limits for the rolling movement of said jamming member.

UNITED STATES PATENT. OFFICE CERTIFICATE OF CORRECTION Patent No. 3 Dated March 26 1974 Inventor(s) Russell ster It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

In the drawing, FIG. 1, change the reference character "26F at; the right of l to 36 Signed and sealed this 22nd day of Oc-toberdl974.

SEAL) Attest:

MCCOY M. GIBSON JR. -c. MARSHALL DANN Attesting Officer v V Commissioner of Patents FORM Po-mso 0- USCOMM'DC 603764369 [1.5 GUVERNMENY PRINTING OFFICE; 8 69-

Claims

4. In combination, a member operatively arranged for selective rotation in either a clockwise or counterclockwise direction of rotation having an external cylindrical friction surface, and a brake means for exerting a selected extent of opposition against said member in only one said direction of rotation comprising a pair of facing track members defining a track located in a clearance position from said member so as to define a triangular clearance space therebetween of a progressively diminishing volume, a brake shoe disposed in an interposed position for reciprocating sliding movement on one said track member with a cooperating cylindrical friction surface thereof in contacting relation with said friction surface of said member, and a cylindrical jamming member disposed in rolling relation between said track members so as to be movable in response to the sliding directional movement of said brake shoe in the direction of said diminishing volume of said clearance space from a non-braking position of movement along a path of movement defined by said track member into a braking position jamming said brake shoe into braking relation with said member, whereby braking opposition is exerted by said braking shoe against said shaft member only in said braking position of said jamming member.

5. The combination, as claimed in claim 4 including a Spring having a planar body operatively arranged in supporting relation to said pair of track members such that one end of said spring body is adapted to be adjusted in position to correspondingly adjust the position of said brake shoe relative to said member, to thereby permit regulation of the extent of opposition being exerted by said brake shoe against rotation of said member.