US2646139A - Automatic slack adjuster - Google Patents

Description

G. B. DOREY AUTOMATIC SLACK ADJUSTER July 21, 1953 5 Sheets-Sheet. 1

Filed March 27. 1950 M/l ENTOK i A? July 21, 1953 G. B. DOREY AUTOMATIC SLACK ADJUSTER '5 Sheets-Sheet '2 Filed March 27, 1950 IN V EN TOR.

July 21, 1953 G. B. DOREY AUTOMATIC SLACK ADJUSTER 5 Sheets-Sheet 5 Filed March 27, 1950 July 21, 1953 I G. B. DOREY $5 AUTOMATIC SLACK ADJUSTER Filed March 27, 1950 5 Sheets-Sheet 4 July 21, 1953 G. B. DOREY 39 AUTOMATIC SLACK ADJUSTER Filed March 27, 1950 1 5 Sheets-Sheet '5 Patented July 21, 1953 OFFICE AUTOMATIC SLACK ADJUSTER George B. Dorey, Westmount, Quebec, Canada, assignor to Continental Transport Appliances, .Limited, Montreal, Quebec, Canada, a corporation of Canada Application March 27 1950, Serial No. 152,06l

My invention relates to an improved automatic slack adjuster for use in connection with the airbrake system of railway cars and the like.

The objects of the invention among others are; to automatically adjust and maintain the brake cylinder piston travel within the limits of '7 to 9 inches as required by the regulations of the Association'of American Railroads and the Interstate Commerce Commission; to provide a selfcontained unit suitable for application to existing types of cars for automatically adjusting the brake parts and compensate for wear at the brake shoes, levers and pinsytoprovide a mechanism which may be applied directly to the floating parts of the brake lever system and dispense with the use of brackets and extraneous fittings such as are commonly employed for anchoring the adjuster parts to the vehicle or equipment to which the brake is applied; to provide a device for automatically shortening a center rod upon excessive movement of the brake applying means and wherein the shortening effect is produced by mechanism responsive to excessive travel of the brake applying means; and to provide a structure wherein the resilient energy of a spring is employed for operating the take up of slack and to provide mechanism wherein a spring is energized during the brake applying movement and the said energy released upon the occurrence of excessive slack in the brake connections. My

invention further resides in the details of construction entering into the device whereby the desired results are obtained and especially in the mechanism concerned with thebuilding up of resilient energy during the brake applying movement and in the means employed for the retention of said energy until released upon excessive travel of the brake applying means.

For further comprehension of my invention reference may be had to the accompanying drawings wherein: I

Figure l is a plan View of the brake lever system of a railway freight car showing my improved slack adjuster applied thereto, said view showing the center sills and lever carriers conventionally indicated by dash and dotted lines.

' Figure 2 is a plan View of the center rod structure as seen in detached relation.

Figure 3 is a detail plan view of the operating bell crank lever employed with my improvement.

Figure 4 is a vertical elevational end View of the lever shown in Fig. 3. U

Figure 5 is a plan View similar to Fig. 1 except that the brake parts are shown as positioned with the p t n x e ded to be substantially mid- 13 Claims. (01. 188 202) way between the extremes of 7 and 9 inches of travel. Said view also shows the position of the levers in dash and dot lines when the center rod connection is shortened.

Fig. 6 is a plan view on an enlarged scale of my improved device showing a portion of the operating bell crank lever broken away.

Figure 7 is a vertical elevational side view of the structure shown in Fig. 6.

Figure 8 is a vertical end elevational view of Fig. '7 as viewed from left to right.

Figure 9 is a fragmentary View of the improved device showing in side elevation as much of the:

structure as necessary to show the take up device and the actuating means employed for efiecting turning movement of the threaded take up device.

Figure 10 is an end elevational view of the structure shown in Fig. 9 as viewed from left to right.

Figure 11 is a vertical end elevational view of the locking pawl employed for retention of spring energy.

Figure 12 is a side elevational view of the pawl shown in Fig. 11 as viewed from left to right.

Figure 13 is an end elevational view of the lever arm employed in connection with the looking pawl.

Figure 14 is a longitudinal elevational view of the lever shown in Fig. 13.

Figure 15 is an end vertical view of the take up mechanism on an enlarged scale as viewed on a line l5-l5 of Fig. 1 and illustrating the actuating mechanism in fully released position and the locking pawl in released position.

Figure 16 is a View similar to Fig. 15 except that the mechanism is shown as displaced from the released position and the locking pawl is shown as entering the ratchet teeth engaging zone.

Figure 17 is a view similar to Fig. 16 except that the locking pawl is shown as positioned into engagement with the final tooth of the series.

Figure 18 is a fractional view of the structure shown in Figs. 15 to 17 inclusive illustrating the lower part only of the said structure and showing the locking'pawl overriding the toothed portion of the cage and moving to released position.

Figure 19 is a view similar to Fig. 18 except that the locking pawl is shown in the position assumed during the releasing movement of the stored up energy in the torsion spring as the latteruncoils to rotate the take up device.

In said drawings there is indicated by conventional dot and dash lines the usual centersil ls of the underframe designated by the nuit merals Hll!l and secured thereto are brake lever supports conventionally indicated also by dash and dot lines at l I, I2 and I3.

The brake arrangement includes a brake cylinder [4 bolted to a bracket [5 which in turn is riveted or otherwise secured to the car underframe at [6. The brake cylinder through the medium of a push rod ll constitutes the brake applying means, it being understood that the admission of compressed air in the cylinder through the inlet pipe I8 operates to move a piston l9 outwardly and this forward movement sets the brake.

The brake system generally includes top rods 2i] which lead to the trucks (not shown) at the respective ends of the car for operating the brake shoes (not shown). The leverage system extending between the top rods and the pushrod includes live and dead levers indicated at 21 and 22 respectively and said levers are connected together through a center connection structure 23. The center connection structure 23 in the embodiment of my invention shown herein includes two end sections indicated at 24 and 25 respectively which extend from their respective levers and the adjacent ends of the connections are screwthreaded to present right and left threads and the respective threaded ends are united by means of a screw take up device 26 having complementary threads engaging with said end sections. The take up device 26 is preferably in the form of a turnbuckle and variation in the length of the center connection structure is efiected by rotation of said take up device.

The outer end of the live lever 2! is connected to the push rod I! by a pivot 2'! and the opposite end of said lever is pivotally connected to the near top rod 26 at 28. The dead lever 22 is pivoted at one end at 29 to a fulcrum bracket 3i! which in turn is secured to the car structure at 3| and the opposite end of said lever 22 is connected with the near top rod 25 as at 32.

The respective sections 2 1 and 25 of the center connection structure are each formed with a jaw section 33 which straddles the associated lever and connection between each jaw and lever is effected by a pivot M. The take up device 26 is formed with an elongated aperture 35 for the purpose of exposing the threaded ends of the connection sections 24 and 25 and rendering the same available for inspection. The said elongated aperture 35 also permits the insertion of an operating tool whereby the take up may be effected manually. The brake layout as herein described is in itself a complete operating entity and functions in a manner to meet accepted requirements of operation.

My invention is therefore concerned with a device capable of accomplishing automatically such adjustment in the length of the center connection structure as would ordinarily be effected manually. Assuming a brake system having therein in the center connection a screw take up device to shorten the length of said connection upon the development of excessive slack my ingagement in one direction with the member 26 and a pickup engagement when swinging in the opposite direction; a saddle like cage mem er 13 embracing said member 26 and having an extension seating on the live lever; a bell crank lever C pivotally mounted on the cage B and formed with angularly related arms indicated at 3B and 3! respectively for engagement with the lever A and push rod l'l respectively; a torsion spring D encircling the member 28; ratchet teeth E on the cage; a latching pawl F pivotally mounted on the swinging lever A and arranged to engage with the teeth E for retaining the torsion spring D in energized relation; and a spring G acting on the pawl F to control the movement thereof as desired.

The lever A is formed with an apertured hub like portion 38 which encircles a hub portion 39 of the member 26 and on each side of said hub 38 the lever is formed with a hollow chambered portion 40 within which a bodily movable pawl 4| is slidably mounted for engagement with ratchet teeth 42 formed in hub 39 of the member 26.

The hollow chambered portions 40 are preferably circular in shape and at the outer end thereof are each provided with a threaded portion for receiving a cap 43. The outer end of each pawl extends through the cap and the inner end is formed with a detent 44 which is shaped to allow free movement of the lever A with respect to the member 25 during the brake applying movement of the push rod ll. The pawl 4| is provided with a shoulder 45 and intermediate said wall and the related cap 43 there is disposed a coil spring 35 under initial tension to force the pawl inwardly into engagement with the ratchet teeth 42 of the member 25. The hub portion 38 of the lever A is extended lengthwise inwardly towards the live lever 2| and said extension seats in an aperture of a wall 118 which depends from that end of the cage member B which is remote from the live lever, it being understood that said lever A is mounted outwardly of the cage B and rotatably associated with the hub portion 39 of the member 26 and with the depending wall 48 through the medium of said hub 39 and the hub extension 41.

The member 26, beyond the lever A, is provided with a threaded portion 45 which carries a locking nut 50 which operates to maintain the lever A in fixed axial relation to the member 26. The lever A is provided above the hub portion with an upwardly extending arm 5| which extends upwardly int the path of swinging movement of the lever arm 36 of the lever C.

The said lever A includes a depending extension 52 which virtually forms a continuation of the wall 5| and pivotally mounted on said extension 52 is the locking pawl F. The locking pawl F is formed with a detent portion 53 which is arranged to engage with the series of teeth E formed in the lower edge of wall 48.

The pawl member F includes an elongated shaft portion 54 which is mounted in an elongated hub 55 which extends laterally outwardly from extension 52 and the pawl is thereby provided with a stable mounting. The shaft portion 54 projects beyond the hub 55 for a limited distance as indicated at 56 to receive a lever arm member 51.

The lever arm member 51 is formed with a collar 58 which fits over the shaft extension 56 of the pawl F and a rivet 60 extends through said respective members in order to unite the pawl and lever member and cause said two members to rotate in unison. The lever arm member 51 includes a pair of spaced Walls Bl-Bl apertured atf-62 for the reception of a pin t3 whereby the springC: ispivotally "connectedto'the arm member 57. The opposite end of spring G isanchored to the lever A'by means of a washer plate .64 received and held between one of the caps 53 and the adjacent lever structure. The extension :52

of thelever A is also provided with an apertured hub portion 65 within which an end 66 of the torsion spring D is received and held.

The cage member B is preferably formed'from a flat plate including a body portion iii which overlies the member 26 and in combination with teract such twisting as necessarily develops in theoperation of the screw take up device.

Intermediate the end wall 48 and the live lever there is provided a second depending wall 69 which leads downwardly 'from the body portion 6'! of the cage member and embraces that end of member 26 which is remote from wall 28.

I The member 26, outwardly of wall 69, is formed with a headed section it which lies immediately adjacent the outer face ll of wall 89 and restrains the said member 253 against axial movement in one direction. 'The member 2% and the cage member B are thus maintained in a definite axial relation being held at one end by the nut 58 and lever A in co-operation with wall 53 and at the opposite end by the headed section iii in co-operation with wall 69.

The body portion 5'! for the major portion of its length is flanged downwardly as indicated at E2 and in oneof said fiangesthere is formed an in dentation 73 for receiving the free end i l of the torsion spring 'D and preventing longitudinal creeping thereof,

The lever C is pivotally mounted to swing in a plane substantially parallel with the plane of movement of the levers 2i and 22 and is pivotally mounted on a ferrule 35 which in combination with a surmounting washer it is secured to the body plate portion '57 of the cage member by a rivet El. Thelever C in the embodiment of my invention shown herein is formed with the arm 36 extending in the general direction assumed by a the center connecting structure 23 and is arranged to swing in a plane to intersect the upwardly extending arm 5| of the lever A and displace the latter as the push rod i'l moves in a direction to apply the brakes. That portion of the arm 5! which engages with the lever arm 36 is of .arcuate concave shapeas indicated at 78 thereby assuring for favourable contact between the intersecting surfaces of the respective levers throughout a wide range of swinging movement of the lever A. a

ing fulcrum in a definite location to the brake applying means andforms a basefrom which the travel of the piston is controlled with precision. This last named condition is well illustrated by reference to Fig. 5 wherein the center connection structure and associated levers are indicated in full lines with the rod fully extended as with new brake shoes and the position assumed by the rods and levers when the connection is shortened is indicated by dash and dotted lines.- 7

A slot 89 is formed in the heel portion 68 of the cage member B in order to permit the live lever 2i to approach the take up member 28 upon operation of the latter in a slack take up direction. 1

The opposite arm 37 of the bell crank operating lever C is extended to engage with the outer end of the live lever 2! being pivotally united therewith and with the pushrod ll by means of pivot 2?. The outer end of arm 31 which receives pivot 22' is provided with an elongated slot'lfi to compensate for variation in the angularity between the arm 3'! and that of the live lever H as the outer ends of said levers travel in unison with the push rod while fulcruming about different pivotal centers.

The mounting of the bell crank operating lever C in definite axial relation with respect to the take up device as represented by the turnbuckle The novelty of my invention and the method of effecting the desired result may be best understood by following out the sequence of operations involved in the setting and releasing of the brakes and culminating in the operation of my improvement as follows: Assuming the brake levers and push rod positioned as in Fig. l with the brake in the released position and the push rod bottomed, the lever C is then positioned with the arm as in contact with the lever A as shown in Fig. 15. In this position, the pawl F is well to one side of the teeth E and there is not any engagement between said teeth E and the pawl F. Upon forward movement or" the push rod I! the arm 35 sweeps along the upper surface of the cage and moves the arm 5! of the lever A rotating the latter about its axial mounting and moving said arm 55 sideways as indicated in Fig. 16. As the lever A swings from the position shown in Fig. 15 to that shown in Fig. 16, the pawl. F tilts about its pivotal axis to an engaging position with the teeth E of the cage B and the tension in the spring D meanwhile increases and is retained by reason of the interengaging relation between the detent 53 of the pawl F and the teeth E1. Should the piston movement be a limited one the pawl F will engage with the first or second of the teeth E" and the spring tension retained thereby until such time as further forward movement of the piston develops andsufiicient additional travel of the push rod takes place to bring the pawl F into engagement with the next succeeding tooth E.

As further forward movement of the push rod develops the next succeeding teeth E will be engaged one after the other until the position shown in Fig. l? is assumed by the pawl F in which position the last of the teeth E. is engaged by the pawl. Continued forward movement of the pushrod causes the pawl F to override the teeth E and the position shown in Fig. 18 is then assumed by the the torsion spring D is preferably arranged to take effect when the pushrod ll reaches a location midway between the limitation of '7 to 9 inches of piston travel and with the parts generally positioned as in Figure 5.

During the release movement of the torsion spring D there is no engagement between the detent 53 of the pawl F and the teeth E as the pawl is maintained in overbalanced position by the spring G as indicated in Fig. 19.

With my improved system of retaining spring energy in a state of storage until required for the take up of excessive slack, it will be apparent that a reliable source of energy is always readily available for taking up the slack as required. The fact that the storing of the resilient energy is accomplished during the brake applying movement and may be built up in a series of brake applications to a maximum assures the building up of the necessary operating force without interfering with the normal operation of the braking system. In fact the loading of the spring D becomes effective with the first application of the brake and the loading does not interfere with the operation of the brake inasmuch as the center connection 23 and its associated cage B function with equal efficiency whether the spring D is energized or not.

The operating parts of my improved take up device as represented by parts A to G inclusive are not subject to stresses incidental to the operation of the brake and being supplementary to the usual brake rods, levers and pins may be constructed of comparatively low cost material and formed of light weight metal.

While I have shown the operating lever C as pivotally united with the pushrod as representing the brake applying means, it will be understood that other forms of brake applying means may be utilized as for example a pull rod may be substituted for the push rod at the end of the live lever without in any way afiecting the operation of my device.

What I claim as new is:

l. The combination, in a braking system including a live lever, a dead lever, a connecting structure therebetween intermediate their ends having a screw threaded device for varying the length of the connection, and brake applying means connected to the live lever to move it in brake setting direction, of spring actuated means carried by said connecting structure for turning said screw threaded device in a direction to remove slack from the braking system and being tensioned by said brake applying means on operation in brake applying direction, interengaging latching means cooperating with said spr ng means to retain the same under tension independently of said brake applying means, and means disengaging said latching means upon over-travel of said brake applying means and thereby releasing said spring means to turn said screw threaded device to remove slack from the braking system.

2. The combination, in a braking system including a live lever, a dead lever, a connecting structure therebetween pivotally connected thereto intermediate their ends and divided lengthwise into sections having right and left hand threaded portions interconnected by a complementary threaded element, and brake applying means connected to the live lever to move it in brake setting direction, of spring means acting on said connecting structure for rotating said threaded element in a direction to remove slack from the braking system and being tensioned by said brake applying means on operation in a brake applying braking system.

3. The combination, in a braking system including a live lever, a dead lever, a connecting structure therebetween pivotally connected thereto intermediate their ends and divided lengthwise into sections having right and left hand threaded portions interconnected by a complementary threaded element, and brake applying means connected to the live lever to move it in brake set ting direction, of a cage movable with said threaded element, spring actuated means carried by said cage for rotating said threaded element in a direction to remove slack from the braking system, a lever extending from said brake applying means for tensioning said spring means and having a pivotal connection with said cage and angularly related arms extending in opposite directions from said pivot, one of said arms being actuated by said brake applying means and the other operating to tension said spring means on operation of said brake applying means in a brake setting direction, coacting pawl and ratchet means cooperating with said spring means to retain the same under tension, and means disengaging said pawl from'said ratchet upon travel of said brake applying means beyond a predetermined distance thereby releasing said spring means to rotat said threaded element and remove slack from the braking system.

4. The combination, in a braking system including a live lever, a dead lever, a connecting structure there'between pivotally connected thereto at points spaced from their ends and including sections having threaded ends and a turnbuckle having screw threaded ends cooperating with the threaded ends of said sections to provide an adjustable connection, and brake applying means pivotally connected to the live lever at a point spaced from the connecting structure, of an actuating member coacting with said turnbuckle for turning the same and swingable in a plane generally parallel to its axis of rotation and independently thereof on operation of said brake applying means in a brake setting direction, and means for effecting movement of said actuating member in unison with said turnbuckle including a spring tensioned by operation of said brake applying means in the brake settin direc tion, interengaging ratchet and pawl means for retaining said spring under tension, and means disengaging said pawl from said ratchet upon operation of said brake applying means beyond a predetermined location thereby releasing said spring to rotate said turnbuckle and remove slack from the braking system.

5. In a slack adjuster, in combination, a live lever; a dead lever; a connecting structure extending between said respective levers and pivotally united therewith at a location spaced from the ends of said levers, said connection being divided lengthwise into two sections and the adacent ends of the respective sections screw threaded to present right and left hand threads; a turnbuckle having complementary threads en gaging with the respective sections; a fluid operated pressure applying means including a push rod pivotally united with the live lever at a location spaced from the connecting structure; a cage I member having one end seating on the live lever mounted on the turnbuckle for oscillatable movement; pawl and ratchet mechanism connecting the swinging lever and turnbuckle to provide for 7 free movement between the said lever and turnbuckle in one direction of swinging movement andv for engagement between said lever and turnbuckle upon movement in the reverse direction; a torsionspring encircling the turnbuckle and engaging with the swinging lever and cage respectively, said spring being tensioned during the free swinging movement of the lever; pawl and ratchet mechanism carried by the swinging lever and cage respectively for retaining the spring tension; and means for tensioning the spring during the forward movement of the pushrod, said means including a bell crank lever pivoted to the cage and having oppositely extending arms leading therefrom and engaging with the swinging lever and the with the pushrod respectively.

6. In a slack adjuster for the brake leverage system of a railway car having a power operated movable brake applying rod acting on the leverage system for applying the brakes, said leverage system includinga take up device for altering the relation between certain parts of the system to compensate for variations in the brake parts, said take up device being arranged to become efiective automatically upon movement. of the brake applying rod beyond a predetermined dis tance of travel, a spring arranged to be tensioned upon movement of said brake applying rod in a brake applying direction and to operate said take up device in a take up direction upon movement of said brake applying rod in a brake releasing direction, pawl and ratchet mechanism for holding said spring under tension until the aforesaid predetermined travel of said brake applying rod takes place, and means for thereupon operating said pawl and ratchet mechanism to release said spring to operate said take up device and remove slack from the braking system. 1

7. Automatic slack adjusting mechanism for a railway car braking'system having brake applying means including a push rod pivotally connected to one end of a live lever whose other end is pivotally connected to a portion of said braking system and whose intermediate portion thereof is pivotally connectedto a conne'cting'rod and thereby connected pivotally to the intermediate portion of a dead lever having a fixed'pivot at one end and pivotally connected at the other end to the remaining portion of said braking system, said slack adjusting mechanism comprising a turnbuckle interposed between the end sections of said connecting rod and oppositely threaded thereon for drawing the same toward each other to remove slack from the braking system, a spring operatively connected to said turnbuckle for rotating it in the slack removing direction, operating means interconnecting said push rod and said spring to operatively tension the latter on movement of the former beyond a predetermined minimum, detent means for holding said spring in operatively stressedcondition independently of said pushrod, and means for releasing said detent means when. said push rod is moved to a predetermined maximum position to release said spring a for rotating said turnbuckle.

8. Automatic slack adjusting mechanism for a railway car braking system having brake applying means including live and dead levers con- 10 nected to the braking system with the live lever connected for energization to a push rod and the levers interconnected by a connecting rod, said slack adjusting mechanism comprising a take up device interposed in said connecting rod and adapted on rotation to decrease the effective length thereofand thereby remove slack from the braking system, spring means operatively connected to said take up device for rotating it in a slack removing direction, force transmitting means operatively interconnecting said push rod and said spring for tensioning the latter through an extent corresponding to the amount of slack developed in the braking system as a result of repeated application of the brakes, and restraining means cooperating with said spring for holding the same under tension independently of said pushrod andbeing operated when said push rod is moved to a predetermined position to release said spring for rotating said take up device and remov ng slack from the braking system.

9. Automatic slackadjusting mechanism for a railway car braking system operated by displacement of a member on operation of brake applying means comprising, in combination, a rod through which braking force is applied to the system, a take up device interposed in said rod and adapted on rotation to change the length thereof and thereby remove slack from the braking system, a spring arranged tobe tensioned upon displacement of said member in a brake applying direction and-to operate said take up device in a take up direction upon displacement of said member in a-brakereleasing direction, releasable means cooperating with said spring to hold the same system, a take updevice interposed in said rod and adapted on rotation to change the length thereof and thereby remove slack from, the braking-system, a spring for operating said take up device, a lever operatively interconnecting said member and said spring to tension the latter on predetermined movement of the former in a brake applying direction, restraining means cooperating with said spring to hold the same under tension independently of force transmitted through said lever until there is a predetermined displacement of said member in the brake applying direction, and means for thereupon operating said restraining means to release said spring to operate said take up device and remove'slack from the braking system.

11. Automatic slack adjusting mechanism for a railway car braking system operated by displacement of a member on operation of brake applying means comprising, in combination, a rod through which braking force is applied to the system, a turnbuckle interposed between the end sections of said rod and oppositely threaded thereon for changing the length thereof and thereby removing slack from the braking system, a lever pivoted intermediate its ends with one end arranged to be operated by said member, spring means operatively connected to the other end of said lever to be tensioned thereby when it is moved in a brake applying direction and operatively connected to said turnbuckle for rotating the same to remove slack from the braking system, and restraining means cooperating with said spring means for holding the same in stressed condition and arranged and adapted to be operated on movement of said member to a predetermined position to release the energy stored in said spring means for rotating said turnbuckle when braking force no longer is applied by said brake applying means.

12. Automatic slack adjusting mechanism for a railway car braking system having brake applying means including live and dead levers connected tothe braking system with the live lever connected for energization to a pushrod and the levers interconnected by a connecting rod, said slack adjusting mechanism comprising, a rotary take up device interposed in series in said brake system so that on rotation thereof the operating relation between the levers and pushrod is changed and thereby slack is removed from the braking system, spring means acting on said take up device for rotating it in a slack removing direction, force transmitting means operatively inter-connecting said pushrod and said spring means for tensioning the latter upon movement of the pushrod, restraining means cooperating with said spring means for holding the same under tension independently of said force transmitting means, and means for releasing said restraining means when said pushrod is moved to a predetermined position to release said spring means for rotating said take up device and removing said slack from the braking system.

13. Automatic slack adjusting mechanism for a railway car braking system having brake applying means including live and dead levers co'n=v the latter upon successive further movements of the former beyond a predetermined movement, restraining means cooperating with said spring means for holding the same under tension after each said further movement of said pushrod and independently of said force transmitting means, and means for releasing said restraining means when said pushrod is moved to a predetermined position beyond any of said further movements thereof to release the energy stored in said spring means for operating said take up device and removing slack from the braking system.

GEORGE B. DOREY.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,961,919 Anderson June 5, 1934 2,283,956, Brown May 26, 1942 FOREIGN PATENTS Number Country Date 221,555' Great Britain 1924 252,178 Great Britain Oct. 28, 1926

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