US3351302A

US3351302A - Apparatus for paying out wire

Info

Publication number: US3351302A
Application number: US434290A
Authority: US
Inventors: Ernest U Lang
Original assignee: National Standard Co
Current assignee: National Standard Co
Priority date: 1965-02-23
Filing date: 1965-02-23
Publication date: 1967-11-07
Anticipated expiration: 1984-11-07
Also published as: DE1499082A1; DE1499082B2; GB1133716A; FR1464404A

Description

Nov. 7, 1967 E. u. LANG APPARATUS FOR PAYING OUT WIRE 2 Sheets-Sheet 1 Filed Feb. 23, 1965 $7 WJW W Nov. 7, 1967 E. u. LANG 3,351,302

APPARATUS FOR PAYING OUT WIRE Filed Feb. 25, 1965 2 Shets-Sheet z Wig-{i219 United States Patent 3,351,302 APPARATUS FOR PAYiNG GUT WIRE Ernest U. Lang, Niles, Mich, assignor to National- Standard Company, Niles, Mich, a corporation of Delaware Filed Feb. 23, 1965, Ser. No. 434,259 tClaims. (Cl. 242-4562) ABSTRACT 0F THE DISCLOSURE The present invention relates to apparatus for paying out coiled material, such as wire, wound on a reel from the reel to a place of use of the material.

In many utilizations of wire such as welding wire and wire for spring and staple fabricating machines, relatively low wire speed delivery is desirable, such as of the order of 150 feet per minutes or less. In such instances it has been the practice to use so called small packages of wire as the supply source in that presently known let-off stands are not satisfactorily operable to provide for the feeding of wire under substantially constant tension at speeds of the order noted. It is one purpose of the present invention to provide let-off apparatus for supporting a large reel package of wire, for example, of the order of 1000 pounds, from which wire may be Withdrawn at low pulling forces, for example, of the extent of 6 pounds, and at low linear speeds of the aforenoted order and under substantially constant tcnsion.

Further, presently known let-ofi apparatus embody a pivotally mounted festoon arm for supporting a sheave over which wire from a reel is trained in drawing the Wire off of the reel, and which festoon arm by its own weight or by being spring loaded solely provides for actuating a brake for braking the reel when withdrawal of wire from the reel is terminated. In such known constructions, a large releasing force of the withdrawn wire is required to actuate the reel brake and hence are not satisfactory in the typical instances above mentioned. It is a further purpose of the present invention to provide a let-off apparatus embodying brake means for yieldingly braking the reel at low brake torque as wire is withdrawn therefrom, and which is self-energizing upon reduction of the small or slight releasing force of the withdrawn wire to provide positive or non-yielding application of the brake means to the reel under relatively high brake torque.

In view of the foregoing it is an object of the present invention to provide a let-01f apparatus embodying festoon means for storing material drawn off a coil carried by a reel supported on the stand for the apparatus, and means for the festoon means operable to maintain material drawn from the festoon means under substantially constant tension.

A further object of the invention is to provide a letolf apparatus in which the reel carries a brake drum and brake shoe means therefore is associated with the festoon means, and together with means for normally yieldingly engaging the brake shoe means at low torque with the brake drum when material is being drawn olf the reel, and, in which, such last named means effects self en- Patented Nov. 7, 1967 ergization of the brake shoe means into substantially nonyielding engagement at high brake torque with the brake drum upon termination of withdrawal of material from the festoon means.

The above and other objects and advantages of the invention will be apparent from the following detailed de scription of a preferred embodiment of the invention.

Now in order to acquaint those skilled in the art with the manner of constructing and operating a let-off ap paratus in accordance with the principles of the present invention, there is described below in connection with the accompanying drawings a preferred embodiment of the invention.

In the drawings:

FIGURE 1 is a side elevational view of a let-off apparatus constructed in accordance with the principles of the present invention;

FIGURE 2 is an end elevational view looking toward the rear of the let-off apparatus of FIGURE 1;

FIGURE 3 is a detail side elvational view of brake shoe means for engaging a brake drum on a reel carrying a coil of wire mounted on the stand of FIGURES 1 and 2, and showing a slide member of brake shoe mounting means for mounting the brake shoe means on the festoon arm of festoon means of the stand; and

FIGURE 4 is a detail view of shaft means for supporting a reel for a coil of wire, and a brake drum for the reel embodied in the apparatus of FIGURES 1 and 2.

Referring now to FIGURES l and 2 of the drawings, there is shown a let-off apparatus constructed in accordance with the present invention and which in the main comprises frame means 1, a reel and shaft assembly 2 supported on the frame means 1, brake means for the shaft and reel assembly indicated generally at 3, and festoon means for wire withdrawn from a coil on the reel indicated by the reference numeral The frame means 1 comprises a pair of laterally spaced apart

side frame members

5 and 6 extending upwardly from a base member 7. The

side frame members

5 and 6 intermediate their ends have support means 8 and 9 mounted on the outer surfaces thereof and which support means 3 and 9 have upper cam follower supporting surfaces 10 lying above the upper edges of the

side frame members

5 and 6 for purposes to be herinafter described in greater detail, it being sufiicient for the present to note that the reel and shaft assembly 2 is mounted thereon for rotation about a fixed horizontal axis to provide for withdrawing of wire from the reel. It will be understood that the letofif apparatus of the present invention has utility for use With coils of material other than wire such as natural or synthetic filaments and for strands comprising monofilament or multifilament coiled material. The word wire" is thus used herein in the generic sense to mean metal Wire or other coiled filaments as typified by those last above noted.

The festoon means 4- comprises a first fixed standard 14 securely mounted outwardly of and on side frame member 5 to project upwardly and forwardly of the main frame 1 and which at its outer end carried a first wire guide, such as a sheave 16, rotatably mounted about a fixed axis at the outer end of axle pin 17 mounted at the upper end of the standard to position the sheave is in a vertical plane lying substantially centrally between the

side frame members

5 and 6. The festoon means 4 further comprises a festoon arm 18 pivotally mounted at its lower end in a bearing block 19 on the base 7 of the main frame 1 and lying inwardly of the inner surface of the side frame member 5. The festoon arm 18 is defined by a first leg portion 22 extending generally forwardly and upwardly of the main frame 1, a second leg portion 23 extending generally upwardly and rearwardly of the 3 frame, and a third leg portion 24 extending further rearwardly and upwardly of the main frame, and which at its outer end carries a second wire guide in the form of a sheave 25 rotatably mounted about a fixed axis on an axle pin 26 carried at the outer end of the festoon arm. Festoon arm 18 is normally biased for rotation in a clockwise direction as viewed in FIGURE 1 tending to space apart the first and second

wire guide sheaves

16 and 25 for storage of wire withdrawn from the coil. The wire w from the coil is adapted to be trained over the first sheave 16 and then to and around the second sheave 25 from which it extends to its place of utilization. In accordance with the present invention, spring means, indicated generally at 30, is arranged between the festoon arm 18 and the main frame 1 of the stand to provide, as will be hereinafter described, for the drawing of wire otf of the coil under substantially constant tension over a predetermined range of pivotal movement of the festoon arm 18 and within the wire storage capacity of the festoon means. The spring means 30, as seen in FIGURE 1, comprises a link 32 pivotally secured at its outer end to leg portion 23 of the festoon arm 18 close to the juncture of the latter with the first leg portion 22, and a coil tension spring 33, connected at its inner end to the other or outer end of the link 32, and with the outer or other end of coil spring 33 being anchored, as at 34, on an anchor member 35 rigidly connected to the base 7 of the frame 1. It will be observed that the axis of the spring means 33 as indicated, at xx, extends angularly upwardly and forwardly from the base of the stand and in converging relation to leg portion 22 of the festoon arm 18. As shown in FIGURE 1, a resilient spring bumper 37 is mounted inwardly of the inner surface of the side frame member and in position to be engaged by the leg portion 22 of the festoon arm 18 to limit pivotal movement of the festoon arm 18 around its pivot 19 in a counterclockwise direction. Also, as shown in FIGURE 1, a reaction member 36 attached to side frame member 5 limits the clockwise pivotal movement of the festoon arm caused by self energization of brake means 3,'hereinafter described in greater detail, upon termination of withdrawal of the wire.

In the apparatus thus far described it will be noted that upon drawing wire w over sheave 16 and sheave in the initial movement of the wire at the source of use the festoon arm 18 will move in a counterclockwise direction about its pivot 19 initially taking out the wire stored between the

sheaves

16 and 25. In such initial starting operation the inertia of the reel and the coil of wire thereon is overcome. The festoon arm may rock to engage the resilient bumper 37 should wire speeds in excess of about 150 feet per minute be attained. Of course, a larger wire tension will be needed to accelerate a 1000 lb. reel above the constant tension design speed of the apparatus. Thereafter, the festoon arm 18 will back off or move in a counterclockwise direction and the festoon arm will shortly assume a position in which there is no hunting, that is with the hereinbelow described brake shoe means 48 lightly engaging a brake drum 44 carried by the reel. It will be noted that in relative movement of sheave 25 toward and away from sheave 16 of the festoon means that the effective lever arms of the spring means will vary to provide for constant tension of the withdrawn wire over a predetermined range of movement of festoon arm such as the distance Y indicated on FIGURE 1. In this regard, it will be observed upon movement of the festoon arm 18 in a counterclockwise direction from the position shown the axis x--x shifts downwardly and forwardly shortening the distance indicated at L between the pivot 19 of the festoon arm 18 and the axis xx of the spring means 30 thus decreasing the effective lever arm in proportion to increasing the force component of spring 33 as it is linearly extended. The distance L between the center line x-x of the spring means 30 and the pivot 19 of the festoon arm 18 upon movement of festoon arm 18 will vary providing a varying effective lever arm for the uniform maintenance of torque and withdrawal of wire w under substantially constant tension in the predetermined range spaced apart normal storage capacity between the

sheaves

16 and 25. When the sheave 25 exceeds its normal storage capacity position the spring bumper means 37 effects gradually increasing tension to the withdrawn wire as indicated at z. In connection with loading a reel having a coil of wire thereon onto the stand as will be later described it will be observed that a hook member 40 is pivotally mounted on the pin 17 supporting sheave 16 and which is adapted to be engaged with a pin 42 on the leg portion 24 of the festoon arm 18 to hold the festoon arm 18 well forwardly of the frame.

In connection with the aforementioned components providing for substantially constant tension of wire withdrawn from a reel over a predetermined range of move ment of the festoon arm, it will be observed that brake means, indicated generally at 3, provides for the retarding rotation of the reel so that it does not overrun wire being withdrawn from the coil. The brake means 3 as best seen in FIGURES 1, 3 and 4 comprises a brake drum 44 suitably mounted on shaft means 45 of the reel and shaft assembly 2, and from which a pair of pins 46 project axially and into openings provided in the adjacent reel side plate 47. The brake means 3, as seen in FIGURES 1 and 3, further comprises brake shoe means 48 defined by a pair of

leg members

52 and 53 which at their diverging outer end portions carry

brake shoes

54 and 55 for braking engagement with the P ripheral surface of the brake drum 45. A transverse reinforcing plate 56 connects the

leg members

53 and 54 inwardly of their diverging end portions, and a spring holder, in the form of a rigid hollow pipe 57, is mounted on the plate 56 to lie between parallel spaced apart upper portions 58 and 59 of the

arms

52 and 53. A plate member 60 extends across and is secured to the upper ends of the legs 58 and 59. Brake spring means in the form of coil spring 62 is received and supported in the rigid hollow pipe 57. Brake shoe mounting means for mounting the brake shoe means 48 on the festoon arm 18 comprises a slide member 65 mounted between the parallel portions 58 and 59 of the

legs

52 and 53 of the brake shoe means for movement between. end plate 60 and the open upper end of hollow pipe 57. The slide member 65 is formed with an opening into which a pin 66 carried by the leg portion 23 of the festoon arm 18 is received. The slide 65 is thus mounted for sliding relation between the arms 58 and 59 of the brake shoe means in response to movement of the festoon arm 18. A coil spring 67 extends between festoon arm 18 and brake shoe means 48 to position the latter with respect to the brake drum 44.

In normal operation of drawing wire w from the reel, the brake spring means 62 will be loaded between the slide 65 and the plate 56 of the brake shoe means to yieldingly bias or engage the

brake shoes

54 and 55 into engagement with the periphery of the drum over a predetermined range of movement of the festoon arm toprevent the reel from overrunning the wire being withdrawn from the reel. Upon movement of the festoon 18 to a predetermined end position in the clockwise direction at which the slide 65 fully collapses the brake spring means 62 within the hollow pipe 57, the slide 65 will then rigidly engage the hollow pipe 57 and, when this occurs, the brake shoe means 48 will self energize into substantially non-yielding engagement with the surface of the brake drum 44. The foregoing self-energization of the brake shoe means 48 with the brake drum 44 results due to the relationship of the axis of rotation of brake drum 44 about the fixed horizontal axis of shaft means 45 and the arcuate path of movement of pivot 66 for the brake shoe means 48 carried by festoon arm 18 as defined by its pivot 19. Thus, as seen in FIGURE 1, as the festoon arm rotates in a clockwise direction about its pivot 19, the pivot 66 follows an arcuate path advancing toward the axis of shaft means 45 so that at a predetermined position of festoon arm 18 the brake shoe means 48 engage the brake drum to thus effect se-lf-energization of the brake shoe means into substantially non-yielding engagement with the brake drum. The brake torque thus applied to the brake drum is many times that of the yielding frictional braking action in the normal operation of drawing wire w from the reel. Thus, upon discontinuing drawing of wire from the reel or breakage of the wire when the festoon arm 18 approaches its predetermined end clockwise position, large or high brake torque through self-energization of the brake shoe means arrests movement of the reel and holds it against rotation. Thus, in the operation of the apparatus, a small or slight releasing force is sufiicient for the wire to be withdrawn from the spool. But, as the festoon arm is positioned toward its predetermined end clockwise position the self-energizing action of the brake means provides for application by toggle action of the brake shoe means to the brake drum.

The apparatus shown in the drawings provides for the facile and easy manual loading of a heavy reel and wire coil thereon onto the frame 1. It will be observed that the frame means is provided with a tread member 70 having a surface 71 inclined upwardly and toward the front end of the frame 1. A pair of

ramps

73 and 74 are securely mounted to the

side frame plates

5 and 6 at the inner surfaces thereof and at the upper edges of the side frame members to dispose the

ramps

73 and 74 with their upper surfaces 75 lying above the upper edges of the

side plates

5 and 6. The edge ramp surfaces 75 are inclined slightly upwardly and inwardly of the frame toward the front end thereof and the aforementioned supporting means 8 and 9 are disposed in juxtaposition of the

ramps

73 and 74. The cam follower supporting surfaces 10 of the supporting

means

8 and 9 lie laterally outwardly of the surfaces of the

ramps

73 and 74 to receive cam followers 83) and 81 mounted, respectively, at opposite ends of the shaft means 45 of the assembly 2. The

cam followers

80 and 81 are preferably low friction rollers and are secured to the ends of the shaft 46 in any suitable manner. Brackets '82 and 83 as best seen in FIGURES 1 and 2 have

latches

84 and 85 pivotally mounted thereon so that when the

cam followers

80 and 81 are supported on the cam follower surfaces 10 of the supporting

means

8 and 9 the

latches

84 and 85 may be swung in position over the cam followers to retain the reel and drum assembly in position on the frame as shown in FIGURE 1.

In loading a reel with a coil of wire thereon onto the frame the festoon arm 18 is first disposed to its end counterclockwise position to dispose the brake shoe assembly 3 in position free of the brake drum of the reel to be placed on the frame. The festoon arm is held in such position as above described by the aforementioned latch and pin 42. The reel is then positioned with the portions of the peripheries of the reel sides in engagement with the inclined surface 71 of the tread 70, and upon movement of the reel on the peripheries of its rims inwardly of the frame, the reel is raised slightly to dispose portions of the shaft means onto the surfaces 75 of the

ramps

73 and 74 with the reel then rolling into the frame on these ramp surfaces to the point where the cam followers $0 and 81 engage with the cam follower supporting surfaces 1% of the support means 8 and 9, respectively. Thereafter, the

latches

84 and 85 are disposed to the position shown in FIGURE 1 to retain the reel in position on the frame. The latch 40 may then be released from the pin 42 and the festoon arm moved in a counterclockwise direction to engage the brake shoes of the brake shoe means with the surface of the brake drum. Thereupon, upon stringing of the wire through the festoon as before described, the let-off apparatus is ready for operation. It will be observed that in loading a reel onto the let-01f stand as above described that only a portion of the necessary work is achieved by rolling the peripheries of the reel sides up inclined surface 71 of the tread 70. A preliminary roll of less than one inch is sufficient to easily roll the reel to the point at which shaft means 45 is deposited onto surfaces 75 of the

ramps

73 and 74. Thereafter, and during the major portion of the work, a large mechanical advantage is available since the reel must rotate more than one revolution on the periphery of its shaft means 45 while only a small force is applied manually on the periphery of the reel sides until disposal of the cam followers and 81 on the cam follower surfaces 10 of the support means 8 and 9.

While a preferred embodiment of the invention has been shown and described, it will be understood'that various modifications and rearrangements may be made therein without departing from the spirit and scope of the invention.

The invention claimed is:

1. In an apparatus of the class described the combination of frame means, a reel having a coil of wire or the like wound thereon, means for rotatably supporting said reel on said frame means, festoon means comprising a first wire guide mounted on said frame means, a festoon arm pivotally mounted at one end thereof on said frame means, and a second wire guide mounted at the other end of said festoon arm and movable relative to said first wire guide by pivotal movement of said festoon arm about its pivot for storing wire drawn from said reel between said first and second wire guides, means extending between said festoon arm and said frame means for maintaining wire drawn ofl of said second wire guide under substantially constant tension over a predetermined range of pivotal movement of said festoon arm, a brake drum carried by said reel, brake shoe means for said brake drum, brake mounting means for mounting said brake shoe means on said festoon arm, brake spring means between said brake mounting means and said brake shoe means for yieldingly biasing said brake shoe means into engagement with said brake drum over a predetermined range of movement of said festoon arm, and said brake mounting means at a predetermined position of said festoon arm collapsing said brake spring means to dispose said brake shoe means in self-energizing and substantially non-yielding engagement with said brake drum.

2. In an apparatus of the class described the combination of frame means, a reel, means for rotatably supporting said reel on said frame means, festoon means comprising a festoon arm mounted for movement on said frame means, a brake drum carried by said reel, brake shoe means for said brake drum, brake mounting means for mounting said brake shoe means on said festoon arm, and brake spring means between said brake mounting means and said brake shoe means for yieldingly biasing said brake shoe means into engagement with said brake drum over a predetermined range of movement of said festoon arm, and said brake mounting means at a predetermined position of said festoon arm collapsing said brake spring means to dispose said brake shoe means in self-energizing and substantially non-yielding engagement with said brake drum.

3. In an apparatus of the class described the combination of frame means, a reel having a coil of wire or the like wound thereon, means for rotatably supporting said reel on said frame means, festoon means comprising'a first wire guide mounted on said frame means, a festoon arm mounted for pivotal movement on said frame means, and a second wire gniide carried by said festoon arm and movable relative to said first wire guide over a predetermined range of movement of said festoon arm for storing wire drawn from said reel between predetermined spaced apart positions of said first and second wire guides, a brake drum carried by said reel, brake shoe means for said brake drum, brake mounting means for mounting said brake shoe means on said festoon arm, brake spring means between said brake mounting means and said brake shoe means for yieldably biasing the latter into engagement with said brake drum over said predetermined range of movement of said festoon arm, and said brake mounting means at a predetermined position of said festoon arm spacing said first and second wire guides a predetermined maximum distance apart collapsing said brake spring means to dispose said brake shoe means in selfaenergizing and into substantially non-yielding engagement with said brake drum.

4. In an apparatus of the class described the combination of frame means, a reel having a coil of wire or the like wound thereon, means for rotatably supporting said reel on said frame means for drawing wire from said coil, festoon means for wire withdrawn from said reel comprising a first wire guide mounted on said frame means, a festoon arm mounted for pivotal movement on said frame means, and a second wire guide carried by said festoon arm and movable relative to said first wire guide over a predetermined range of movement of said festoon arm for storing wire drawn from said reel between predetermined spaced apart positions of said first and second wire guides, a brake drum carried by said reel, brake shoe means for said brake drum, brake mounting means for mounting said brake shoe means on said festoon arm comprising a slide member pivotally mounted on a fixed axis on said festoon arm and slidably mounted in said brake shoe means, brake spring means between said slide member and said brake shoe means for yieldingly biasing the latter into engagement with said brake drum over a predetermined range of movement of said festoon arm, and said brake mounting means at a predetermined position of said festoon arm spacing said first and second wire guides a predetermined maximum distance apart collapsing said brake spring means to dispose said brake shoe means in self-energizing and substantially non-yielding engagement with said brake drum.

5. In an apparatus of the class described the combination of frame means, a reel having a coil of wire or the like wound thereon, means for rotatably supporting said reel on said frame means for drawing wire from said reel, festoon means comprising a first wire guide mounted on said frame means, a festoon arm mounted for pivotal movement on said frame means, and a second wire guide carried by said festoon arm and movable relative to said first Wire guide over a predetermined range of movement of said festoon arm for storing wire drawn from said reel between predetermined spaced apart positions of said first and second wire guides, a brake drum carried by said reel, brake shoe means for said brake drum, a rigid spring holder open at one end and fixed to said brake shoe means, brake mounting means for mounting said brake shoe means on said festoon arm comprising a slide member pivotally mounted on a fixed axis on said festoon arm and slidably mounted in said brake shoe means, brake spring means in said spring holder extending through the open end of the latter for engagement with said slide member for yieldingly biasing said brake shoe means into engagement with said brake drum and a predetermined range of movement of said festoon arm, and said slide member at a predetermined position of said festoon arm spacing said first and second Wire guides a predetermined maximum distance apart collapsing said brake spring means within said spring holder and rigidly engaging said one end thereof to dispose said brake shoe means into self-energizing and substantially non-yielding engagement with said brake drum.

References Cited UNITED STATES PATENTS 2,215,651 9/1940 Pierce 5 242156.2 X 2,285,654 6/1942 Hanna et al 242 2,419,808 4/1947 Wirth 242-156.2 2,562,990 8/1951 Peebles 242156 X 2,879,011 3/ 1959 Nelson 242156.2 2,905,406 9/ 1959 Falck-Pedersen 24275.43 2,920,840 1/1960 Cooper 242156.2 2,983,468 5/1961 Perrella 242-156.2 3,081,957 3/1963 Van De Bilt 242-156.2 X 3,222,008 12/ 1965 Purzycki 24275.43 3,223,352 12/1965 Fuller et a1. 242-1562 FOREIGN PATENTS 780,164 7/ 1956 Great Britain.

STANLEY N. GILREATH, Primary Examiner.

Claims

1. IN AN APPARATUS OF THE CLASS DESCRIBED THE COMBINATION OF FRAME MEANS, A REEL HAVING A COIL OF WIRE OR THE LIKE WOUND THEREON, MEAN FOR ROTATABLY SUPPORTING SAID REEL ON SAID FRAME MEANS, FESTOON MEANS COMPRISING A FIRST WIRE GUIDE MOUNTED ON SAID FRAME MEANS, A FESTOON ARM PIVOTALLY MOUNTED AT ONE END THEREOF ON SAID FRAME MEANS, AND A SECOND WIRE GUIDE MOUNTED AT THE OTHER END OF SAID FESTOON ARM AND MOVABLE RELATIVE TO SAID FIRST WIRE GUIDE BY PIVOTAL MOVEMENT OF SAID FESTOON ARM ABOUT ITS PIVOT FOR STORING WIRE DRAWN FROM SAID REEL BETWEEN SAID FIRST AND SECOND WIRE GUIDES, MEANS EXTENDING BETWEEN SAID FESTOON ARM AND SAID FRAME MEANS FOR MAINTAINING WIRE DRAWN OFF OF SAID SECOND WIRE GUIDE UNDER SUBSTANTIALLY CONSTANT TENSION OVER A PREDETERMINE RANGE OF PIVOTAL MOVEMENT OF SAID FESTOON ARM, A BRAKE DRUM CARRIED BY SAID REEL, BRAKE SHOE MEANS FOR SAID BRAKE DRUM, BRAKE MOUNTING MEANS FOR MOUNTING SAID BRAKE SHOE MEANS ON SAID FESTOON ARM, BRAKE SPRING MEANS BETWEEN SAID BRAKE MOUNTING MEANS FOR MOUNTING SAID BRAKE SHOE FOR YIELDINGLY BIASING SAID BRAKE SHOE MEANS INTO ENGAGEMENT WITH SAID BRAKE DRUM OVER A PREDETERMINED RANGE OF MOVEMENT OF SAID FESTOON ARM, AND SAID BRAKE MOUNTING MEANS AT A PREDETERMINED POSITION OF SAID FESTOON ARM COLLAPSING SAID BRAKE SPRING MEANS TO DISPOSE SAID BRAKE SHOE MEAN IN SELF-ENERGIZING AND SUBSTANTIALLY NON-YIELDING ENGAGEMENT WITH SAID BRAKE DRUM.