US2287023A - Brake - Google Patents

Description

June '23, 1942- J. CARNES BRAKE Filed Sept. 27, 1941 4 Sheets-Sheet 1 d annes I Cannes June 23, 1942. J. J. CARNES 2,287,023

' BRAKE 2 Filed Sept. 27, 1941 4 Sheets-Sheet 2 Fig.4.

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J. J.= CAIVQNES 2,287,023

BRAKE Filed Sept. 27, 1941 I 4 Sheets-Sheet 4 Fig.8.

gwva/Mov James Carnes Patented June 23, 1942 BRAKE James J. Carnes, United States Army Application September 27, 1941, Serial No. 412,582

(Granted under the act of March 3, 1883, as amended April 30, 1928; 370 0. G. 757) Claims.

The invention described herein may be manufactured and used by or for the Government for I governmental purposes, without the payment to other of the servo-action type, where the pri-" mary shoe is not anchored and presses against the secondary shoe, as illustrated by Patent No.

2,101,425, granted to L. C. Brisson December 7,

1937. In the first case, the primary shoe is selfenergizing and does most of the braking. When the drum revolves in the reverse direction the secondary shoe is self-energizing and does most of the braking. While it is important to have good brakes both when the vehicle is going forward and in reverse, this type brake is open to the disadvantage, in view of the fact that the the greater portion of use of the brakes is while the vehicle is in forward motion, that the lining of' the primary shoe wears out first. In the servo-action type of brake the greater pressure is transferred to the secondary shoe and therefore the secondary shoe lining wears out before the primary shoe lining. A further disadvantage of the servo-action type brake is the fact that unless the shoes are in approximately exact adjustment, the brakes will grab or lock the wheels,

due to the fact that both shoes run with the drum.

It is the primary object of this invention to combine in a single brake mechanism the advantages of the two types of brakes mentioned above and at the same time to provide a brake mechanism which will overcome the disadvantages inherent in either type.

It is an object of this invention to provide a brake mechanism in which each of the brake shoes of the mechanism does the same amount of work whether the vehicle is moving forwardly or backwardly.

A further object of my invention is to provide an improved brake mechanism of relatively simple and inexpensive construction which will afford a positive control and a smooth and efficient action during braking.

Other objects and advantages of my invention when taken in conjunction withthe accompanying drawings in which Fig. 1 is a view in elevation of one of the preferred embodiments of my invention;

Fig. 2 is a diagrammatic view of Fig. 1 showing the relative movement of the elements of Fig. 1;

Fig. 3 is a fragmentary view of an embodiment of the invention using a single link to connect the two shoes;

Fig. 4 is an elevation of an embodiment of the invention adapted for use in small brakes;

Fig. 5 is a view in elevation of another embodiment of the invention and adapted for use in brakes operated either hydraulically or mechanicallyi I Fig. 6 is a view in elevation of an embodiment of the invention in which the link mechanism is connected between the toes of the brake shoes;

Fig. 7 is a view in elevation of a modified form of link mechanism connecting the toes of the brake shoes, and

Fig. 8 is a second modification of the link mechanism shown in Fig. 6, in which an adjustable connecting arm is placed in the linkage system.

I have illustrated my invention as applied to a hydraulic brake adapted to brake a rotating element of a machine, as, for example, the wheel of an' automotive vehicle; but it is to be understood that my invention is in no way limited in its use to this particular adaptation. Throughout the drawings the elements are shown in the position they assume after the brakes are aplied.

p In Fig. 1, l represents a brake drum which is intended to be rigidly fixed to the rotating machine part to be braked; 5 represents a backing element which is intended to be rigidly fixed to the nonrotating part of the machine. The normal direction of rotation of the drum l is indicated by the arrow hence, in the case of an automotive vehicle, said arrow f indicates the direction of rotation of the drum corresponding to forward motion of the vehicle.

Mounted within the drum I is a primary brake shoe 2 and a secondary brake shoe 3 each having on their contact side a suitable friction limng 4. v The backing plate 5 carries fixedly upon it a brake actuating means 9, adjustable anchor pins 8 and I, guide pins II and I2, and an adjustable eccentric l3. The adjustable anchor pins 8 and I are of conventional design such as is shown in United States" Letters Patent No.

will be apparent from the following description 2,161,640, granted June 6, 1939, to S. Schnell.

The brake actuating means 9 may be any suitable wheel cylinder of a hydraulic brake system and is here represented as a two-way acting cylinder. The primary brake shoe 2 is mounted for limited rotation about the adjustable anchor pin 1 adjacent the end of the shoe remote from the actuating means. The amount of rotation and its path are limited by the guide pin l2. The other end of the primary shoe 2 is attached by means of an adjustable link l4 to an .operating arm of the actuating means 9. The secondary brake shoe 3 is attached at one end by means of an adjustable link IE to a second operating arm of the actuating means 9. As will be described later this link l5 acts as an anchor pin for the secondary shoe 3 about which the shoe may have a limited rotation. The amount of rotation of the shoe 3 and its path are determined by guide pin H. Connecting primary shoe 3 are actuating links 8 (only one shown). The links 8 are mounted on an adjustable anchor pin 6 so as to be free to rock about the pin. The ends of links 8 are attached to the shoes 2 and 3 by means of link pins l8 and 24 respectively. The pins In and 24 are fixed to the ends of links 8 and are adapted to be engaged byslots in the ends of shoes 2 and 3 respectively. The adjustable eccentric I3 is provided to coact with brake shoe 2 in order to adjust the brake forthe shoes to their inoperative position. An added spring I! is attached between the backing plate 5 and secondary shoe 3. The purpose of spring I! is to place a greater retractive. force upon secondary shoe 3 so that when the wheel cylinder 9 is operated shoe 3 will be held against link l5 and caused o rotate about link 15 as an axis.

The operation of the embodiment of my invention shown in Fig. 1 will be clear by a consideration of Fig. 2, a schematic diagram showing the movement of the elements of a brake constructed according. to the invention. As the force is applied from the actuating means 9 to the upper portion of primary 'shoe 2, the upper portion of said shoe will be given an outward rotation about anchor pin 1 as an axis in the direction shown by arrow a, forcing the lining 4 of primary shoe 2 into contact with drum I. At the same time the other end of said shoe will be given an inward rotation about anchor pin 1 as an axis in the direction shown by arrow b. This in turn will impart an inwarl -;otation of the endsof links 8 attached to link pin in about the anchor pin 6 as an axis in the direction shown by arrow 0. The other ends-of the links 8 will thus be .given an outward rotation about anchor pin 8 as an axisflin the direction shown by'arrow d. This motion of pin 24 imparts to secondary shoe 3 an outward rotation about anchor pin 15 as an axis in the direction shown remain substantially at rest due to the fact that spring I I is of suflicient strength to overcome the pressure produced by the actuating means 9. It'will be seen-that, as a result of the method of anchoring the brake shoes, while the vehicle is in forward motion the toe of both the primary and secondary shoes will be rotated in the s me sense as the direction of rotation of the drum I. This will effectively cause both shoes to be self energizing. Thus the braking effort of both shoes .will be substantially equal and they willeach b subjected to equal amounts of wear. The advantages of the invention are equally present when the vehicle is in reverse since any tendency of either of the brake shoes to assume more than its share of the braking load is instantly transferred to the other of said shoes through the link mechanism.

Fig. 3 shows an alternate link mechanismwherein a singlelink 23 may be substituted for the pair of links 8 shown in Fig. 1. a solid link 23 is provided with cam ends l8 and 2| adapted to engage correspondingly shaped slots 20 and 22 in the web of the ends of shoes 2 and 3 respectively. The link 23 is mounted to rotate about pin 6. The operation of the device is identical with the construction shown in Fig. 1.

Where is it desired to use the invention in a small brake, it may be diilicult to utilize the construction shown in Fig. 1 and still have sumcient braking area. In such a case the modification shown in Fig. 4 may be used. In this embodiment of the invention the heel of the primary shoe 2 is extended in an inwardly curved manner at 2a so as to overlap the toe of secondary shoe 3. Links 8| are pivoted about pin 6 and carry pins l8 and 24 adapted to engage the slots in shoes 2 and 3 respectively. A hole 25 is placed in the extended heel of the primary shoe 2 to allow movement of the shoe about anchor pin 6. The operation of this form of the invention is identical with the construction shown in Fig. 1.

In Fig. 5 there is shown an embodiment of the invention in which the secondary shoe 3 is floating rather than anchored to the actuating means 8. In this modification springs 26 and 21 attached to an anchor pin 28 replace springs l6 and H appearing in Fig. 1 and apply equal pressure to shoes,2 and 3. The anchor pin 28, in this embodiment, merely acts as a stop to hold the secondary shoe 3 in its proper retracted position. There is also shown a modified form of link 82 which has a rounded cam portion 36 on one arm of the link adapted to coact with a slot in the web of brake shoe 3 and a notched portion 31 on the other arm of the link adapted to coact with a rounded cam 38 on the heel of brake shoe 2. The actuating means 9 causes both shoes 2 and 3 to be forced against the drum I. The link with the drum the pressure in the wheel cylinder 9 is increased. This increase is effective braking force without increase in applied pressure is particularly useful in stopping heavy equipment. In such an arrangement whenthe brake is applied while the drum is rotating in a direction the reverse of that shown by arrow 1, the fact that the secondary shoe 3 is floating allows it to become, in a relative manner, self-energizing. This force is applied through the link 82 and transmitted to the primary shoe 2 thus equalizing the pressure on the two shoes.

For safety it is customary to have an auxiliary mechanicaloperating system for supplementing the hydraulic operating system in case of failure.

An arrangement adapted for this purpose is shown In the figure,

shoes 2 and 3 into contact with drum I.

about its anchor pin 6. to pivot about its anchor pin 39- and puts addi- 2,287,023 in Fig. 5. It is obvious, however, that the arrangement could be applied to any of the embodiments shown in the other drawings with equal success. or could be substituted completely for the hydraulic operating means. The system for applying the mechanical operating force is as follows: on the web of shoes 2 and 3 adjacent their ends remote from link 82 are placed respectively pins 29 and 30. Rotatably mounted on pins 29 and 30 are links 33 and 34 respectively. Link 33 is attached to the body of link 34 by means of pin 3|. Operating arm 35 is attached to the free end of link'34 by means of pin 32. When a force is applied in thedirection of arrow y to the arm 35, the links 34 and 33 tend to rotate clockwise and counterclockwise respectively about pin 3|. This movement imparts an outward motion to pins 29 and 30.forcing the lining '4 of The link 82 acts as before to equalize the pressure on the .two shoes.

A somewhat different system of links which may be used toachieve the benefits of my invention is shown in Fig. 6. In this figure the pair of links 83, only .one of which is shown, instead of being connected to the heel of the pri mary shoe 2, is connected to one end of a pair of crank arms 40, only one of which is shown. The crank arm 40 is mounted to pivot about a fixed anchor pin 39 fixedly'attached to the backing plate 5. The other end of the crank arm is fastened to the link l4 carried by an operating arm of the actuating means 9. The construction 'of the remainder of the brake mechanism is similar to that described in Fig. 1, with the exception that the secondary shoe 3 is mounted to rotate against a fixed anchor pin 4| rigidly attached to the backing plate 5 adjacent the operating means 9.

The operation of this form of link system is as follows: when force is applied by the operating means 9 this force is transmitted through pin M to the primary shoe2 causing it to'rotate outwardly about anchorpin 1 forcing the lining 4 into contact with the drum I. A portion of the actuating force is transmitted to the slotted end of the crank arm 40 by means of pin l4 causing a counterclockwise rotation of the crank 40 about its pivot pin 39. The corresponding movement of the other arm of the anchor 40 istransmitted to the link 83 by means of pin in imparting to said link a clockwise rotation about its pivot pin 5. The correspondingmovement of the other end of the link 83 forces the toe of the secondary shoe 3 to have an outward rotation about anchor pin 4! as an axis, which in turn forces the lining 4 into contact with the drum I. On rearward rotationof the'brake drum the secondary shoe 3 moves away from its anchor 4i slightly and in so doing forces link "to pivot This causes crank 40 tional pressure on the toe of the primary shoe 2.

In Fig. '7 is shown a modification of the arrangement shown in Fig. 6 in which a pair of links 42, only one of which is shown, is connected so that the web of primary shoe 2 pivots in one end of the links "by means of pin 43,. and the other end of said links" pivots in the crank arm 40 by means of pin 44. The from the actuating means 9 is applied. to the links 42 by a pin l4 which pivots atthe center. The purpose of this additional link 42 is to cause both shoes 2 and 3 to content the drum I, even if the shoes do not have the 'same linin drum clearance. The operation of this embodiment of the invention is the same as previously described except the equalizing pressure is now applied through the added adjustment equalizing link 42.

It will be seen that the link 84 of Fig. 7 merely serves to transmit the force of pin II to pin- 24 and for some conditions it may be desirable to make the link 84 an adjustable connecting arm. Such an arrangement is shown in Fig. 8 in which the clevis 85 is attached to link 44 at one end by means of pin it and at the other end to shoe 3 by means of pin 24. The clevis 45 has threaded ends 48-46 adapted to be engaged by lock nuts 45-45 whereby the linkage system may be adjusted. The operation of the linkage system may be aided by an added spring 48 connecting'the upper end of link 40 and the brake shoe 3. To aid in the accurate operation of the secondary shoe 3 it may be found desirable to add an eccentric shoe anchor 41 near the heel of the shoe. The principle of operation of this form of the invention is identical with that disclosedin Fig. 6.

The various embodiments of my invention hereinbefore described and illustrated in the accompanying drawings constitute certain preferred forms of said invention; but I wish it to be understood that I do not desire to be limited to the actual structural details and assemblies shown and described,for obvious modifications thereto will occur to one skilled in the art.

Having described my invention, what I claim as new and wish to secure by Letters Patent is:

1. In a brake, a drum, a backing plate, a primary shoe, a secondary shoe, actuating means to force said shoes into contact with saiddrum, an anchor for said primary shoe placed adjacent the end remote from said actuating means, an anchor for said secondary shoe placed adjacent the end closest to said actuating means, and means connecting the ends of said shoes remote from said actuating means, whereby the braking eii'ect of said shoes is substantially equalized, said last mentioned means including a link pivoted intermediate its ends to said backing plate. 2. In a brake, a drum, a backing plate, a primary shoe, a secondary shoe, actuating means to force said shoes into contact with said drum, means to anchor said primary shoe adjacent the end remote from said actuating means, means to anchor said secondary shoe to said actuating means, and means connecting the ends of said shoes remote from said actuating means. whereby the braking effect of said shoes is substantially equalized, said last mentioned means including a link centrally pivoted intermediate its ends to said backing plate.

3. In a brake, a drum, a backing plate, a pri-,

shoe, said anchoring means including a pin attached to said backing plate and-adapted to engage said primary shoe adjacent said heel, means to anchor the heel or said secondary shoe ad- 'jacent said actuating means, and means connecting the heel of said primary shoe and the toe of said secondary shoe, whereby-the braking efiect of said shoes is substantially equalized, said last mentioned means including a link adapted to pivot intermediate its ends about a pin attached to said backing plate.

4. In a brake, a drum, a backing plate, a primary shoe, a secondary shoe, said shoes each having a toe and a heel, actuating means adapted to force said shoes into contact with said drum,

' means to anchor said primary shoe to said backhaving an operating arm adapted to force said shoes into contact with said drum, means to anchor the end of said primaryshoe remote from said actuating means to said backing plate, means to anchor said secondary shoe adjacent the end closest to said actuating means, and means connecting the unanchored ends of said shoes, whereby the forces applying said shoesinto effect of said shoes is substantially equalized, said to anchor said secondary shoe adjacent said actuating means and means connecting the heel of said primary shoe to the toe of said secondary shoe, whereby the heel of said primary shoe efiectively presses the toe of said secondary shoe into contact with said drum when said actuating force is applied, said last mentioned means including an actuating link pivoted intermediate its ends about a pin attached to said backingplate.

6. In a brake, a drum, a backing plate, a primary shoe, a secondary shoe, actuating means adapted to force said shoes into contact with said drum, an anchor for the end of said primary shoe remote from said actuating means attached to said backing plate, an anchor for said secondary shoe placed adjacent the end closest to said actuating means, and means connecting the unanchored ends of said shoes, whereby the forces applying said shoes into' contact against said drum are equalized, said last mentioned means including an actuating link pivoted intermediate its ends about an anchor pin attached to said backing plate.

'7. In a brake, a drum, a backing plate, a primary shoe, a secondary shoe, actuating means adapted to .force said shoes into contact withsaid drum, an anchor for the end of said primary shoe remote from said actuating means attached to said backing plate, an anchor for said secondary shoe attached to said actuating means, and means connecting the unanchored ends of said shoes, whereby-the forces applying said shoes into contact against said drum are substantially equalized, said last mentioned means including an actuating link pivoted intermediate its ends about an anchor pin 'attached to said backing plate.

8. In a brake, a drum, a backing plate, a'primary shoe, a secondary shoe, actuating means contact against said drum are equalized, said last mentioned means including a linked system having a first link pivoted intermediate-its ends, one end of said first link being connected to the free end of said primary shoe and its other end being connected to one end of a second link, said second link being pivoted intermediate its ends, the other end of said second link being adapted to force said secondary shoe into contact with said drum when said actuating means'is actuated.

9. In a brake, a drum, a backing plate, a primary shoe, a secondary shoe, actuating means having an operating arm adapted to force said shoes into contact with said drum, means to anchor the end of said primary shoe remote from said actuating means to said backing plate, means to anchor said secondary shoe to said actuating means, and means connectin the unanchored ends of said shoes, whereby the forces applying said shoes into contact against said drum are equalized, said last mentioned means including a linked system having a first link pivoted intermediate its ends on said operating arm, one end of said first link being connected to the free end of said primary shoe, the other end of said first link being connected to one end of a second link, said second link being pivoted intermediate its ends about a, pin attached to said backing plate, the other end of said second link being attached to one end of a third link, said third link being pivoted intermediate its ends about a pin at.- tached to said backing plate, and the other end being adapted to force said secondary shoe into contact with said drum when said actuating means is energized.

10. In a brake, a drum, a backing plate, a primary shoe, 9. second shoe, actuating means having an operating arm adapted to force said shoes into contact with said drum, means to anchor the end of said primary shoe remote from said actuating means to said backing plate, means to anchor said secondary shoe to said actuating means, and means connecting th unanchored ends of saidshoes, whereby the forces applying said shoes into contact against said drum are equalized, said last mentioned means including a linked system having a first link pivoted intermediate its ends on said operating am, one end of said first link being connected to the free end of said primary shoe, the other end of said first link being connected to one end of a second link, said second link being pivoted intermediate its ends about a pin attached to said backing plate, the other end of said second link being attached to one end of an adjustable connecting member, the other end of said adjustable connecting member being adapted to force said secondary shoe into contact with said drum when said actuating means is energized.

. I JAMES J. CARNES.

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