Патент USA US2132913код для вставки
Octf 11, 1932s. B. s.> AIKMAN 2,132,913’ BRAKE CONTROL MEANS Filed July 6, 1955 INVENTOR EmRToN _5. AIKMAN :.2: A ì ' M ß ATTORN EY Patented Oct. 11, 1938 2,132,913 ?UMTED STA-TES » PATENT OFFICE i BRAKE coN'rrRoL MEANS Burton S. Aikman, Wilkinsbur'g, Pa., assignor to The Westinghouse Air Brake Company, Wil merding, Pa., a corporation of Pennsylvania Application July 6, 1935, Serial No. 30,121 ' Q 2s claims.V (o1. soséiy My invention relates to brake control means . for vehicles and more particularly to means for controlling braking equipment to' prevent the Wheels from sliding. My invention has application to iiuid pressure 5 ates intermittently to progressively reduce brake cylinder pressure during a brake application. ’It is a further object of my invention to pro vide a brake force releasing device for inter brake equipment employed on railway trains and’ traction vehicles and is effective to intermittently mittent reduction'of brake cylinder pressure, the counteract the eñect of high brake cylinder pres- ' 10 sure during a brake application, at sufficiently frequency of operation of which is such that a high brake cylinder pressure will not be in force frequent intervals, to prevent a highk braking a suñicientvlength of time at any one time, as 10 force from being maintained for a length of time at any one time that is suiiicient to cause actual wheel sliding as the vehicle speed reduces, and to simultaneously cause a gradual reduction in high brake cylinder pressure to a predetermined low value. It is well known that for a given braking pres sure, friction type brakes are less effective in re tarding the motion of a vehicleiat'high speed the vehicle speed decreases, to cause actual Wheel sliding at the existing vehicle speed. ` comprising a brake equipment arranged in ac cordance with one preferred embodiment of the invention, tion between the rubbing Vparts is lowerV at high 20 Fig. 2 is a view in vertical section through the speed than at low speed. When a full service or emergency brake application is made at high brake cylinder and the braking force releasing mechanism, and speed the brake cylinder pressure developed will ' ' f Fig. 3 is a sectional view taken on line 3_3 - exceed the pressure required to slide the wheels on the rails as the speed of the vehicle decreases. of Fig. 2. ~ ' Y Referring to the drawing, a ñuid pressure In order to bring a vehicle to a stop quickly, it brake equipment is illustrated in Fig. 1 in which has been the usual practice for an operator to`> a brake cylinder VI is provided and is supplied apply the brakes with a high degree of braking with fluid under pressure from an auxiliary res pressure at high speed, and, as the speed of the _ ervoir 2 through a brake cylinder pipe 4 in ac vehicle decreases,fto so operate the brakes as to cordance with the operation of a triple valve cause the braking pressure to decrease rin such device 3 as controlled by the pressure in a brake manner that the vehicle is brought to alstop pipe 5 in the usual way. A brake cylinder piston quickly and smoothly, without sliding of the rod or stem 6 is operated in accordance with the supply of fluid under pressure to the brake cyl When railway trains and traction vehicles are inder I and is connected to the lever system in operated at very high speeds, a correspondingly cluding levers 1, 8 and 9, the lever ‘I being con Wheels. » , Other advantages and objects of my invention Will appear from the following description of a specific embodiment thereof taken in connection 15 with the accompanying drawing, in which Fig. l is a diagrammatic view of apparatus . than at low speed because the coeñicient of fric , It is another object of my invention to pro vide a braking force releasing device which oper 25 v high braking force must be employed to Ybring nected to operate the levers I0, II, I2 and I3, which -are pivotally connected together for oper length of time. When such braking force isk ating theA brake shoes I5 and I6 against the applied the problem of properly reducing the YWheels I1 and I8, respectively, that roll along the braking force by manual operation as the vehicle rail> I9. 'The upperend of the lever I3 being the train or vehicle to a stop in KVa reasonableY slows down becomes a difficult one and there is pivctally'connected to the car frame I4, the lever considerable danger of the wheels sliding on the ' V9 of the brake equipment similarly controls the L rails. It is therefore desirable to provide, as a , operation ofthe pivotallyfinterconnected levers part of the brake equipment on high speedtrains 21,22, 23 and 24, for pressing the shoes 26 and and vehicles, means for automatically'reducing 2'! against the wheels 28 and 29', respectively. the braking force suiiiciently to permit the'wheels to maintain rotation and prevent their sliding The'upper end of the lever 24 is pivotally‘ con nected by the pin 25 toa point on the Vcar frame. As illustrated, the'upper end of the lever 1 is 50 5.0. It is an object of >my invention tovprovide a connected to the crosshead end 3I of the piston brake equipment having a braking force releas-vk , stem 6,- and the upper end of the lever 9 is con Von the rails. , ~ ' ` - ing characteristic to intermittently relieve 'the'> neoted to a bifurcated portion 32 of the pressure eilîect of high brake cylinder pressurersuiiiciently head ’of the brake cylinder I, so that movement " to prevent wheel sliding. ' ~ - e of the crosshead 3| away from the pressure head, 55 2 2,132,913 and of the interlinked lever system connected thereto, causes an equalized application of brak » ing forces to the wheels l1, I9, 28 and 29. The operating mechanism for the braking force release device 33 is connected to the pres sure head of the brake cylinder l, as best shown in Fig. 2, and operates from brake cylinder pres sure to partially reduce the braking force below a value corresponding to brake cylinder pressure 10 at intervals determined by the timingr of the releasing device. , ' , The brake cylinder l comprises a casing en closing a piston chamber 34 containing a piston 35 that is connected tc the piston stem or rod 5 which lextendsr outwardly kthrough the non pressure head 39 of the brakecylinder I, and mally limited by the average adhesion of the car wheels to the rails. If the brake shoe forces exceed this permissive value the adhesion of the car Wheels to ,therails is insufficient to prevent the wheels from sliding. Tests show, however, CTI that'a brief period of time exists between what is known as incipiency of Wheel sliding .and actual wheel sliding, that is, a brake shoe pressure suffi cient to cause wheel sliding can be exerted for a short time without actually causing such sliding Y `due to the time element involved. . As the brakes are applied and brake cylinder pressure increases within the piston chamber 34 to a predetermined value, the spring-weighted valve piston 39 will be forced from its seat 49 toward the right against the bias of the spring which is surrounded by a release spring 31, one Y 4|, 'thus permitting fluid under pressure to ñow end of which engages the piston 35 and the other from the piston chamber 34 at piston chamber end of which engages the non-pressure head 3G pressure, through passage 43,. to the piston 20 to bias the piston 35 toward-the right to a brake chamber 44 to force Vthe piston 45 and piston rod 20 releasing position. The braking force release mechanism 33 comprises ak casing enclosing a valve chamber 38 containing a spring-Weighted valve piston 39 that is urged toits seat by a 25 spring 4| to close communication from the pis ton chamber 34 through' passages 42 and 43, to a piston chamber 44 containing a piston 45 that is provided with a stem or piston rod Gil. The braking force releasing mechanism also contains a piston chamber 46 containing a piston 41, illustrated as positioned against a stop 48, and provided with a stem49 that extends centrally through the spring 4I, the end acting as a stop ` for limiting the movement of thev valve piston 35A 39 away from its seat. A chamber 5l between the valve piston 39 and the piston 41 is connected to the atmosphere through an exhaust port 52 so that the pressure Within the chamber 5l is con tinuously at atmospheric pressure. A restricted passage 53 through the piston 41 permits the gradual escape of ñuid under pressure from the piston chamber 46 to the atmosphere. A valve chamber 54 is provided, containing a spring-weighted valve piston 55 that is urged to 45 its seat 56 by a spring 51, the lower end of which engages the valve 55 and the upper end of which engages the wall or partition forming the under side of the chamber 5I. The valve piston 55 con trols communication between the passage 43 and the piston chamber 44 through passage 58 to the piston chamber 46. ' ' The piston 45 is attached by a pin 59 to a piston rod 6l that is pivoted by the pin 62 to a lever 63, the Vupper'portio-n of which is provided with jaws 94 and 55 for gripping the piston rod 6 and moving it slightly to the right, against the pres sure in the piston chamber 34, upon the move ment of the piston 45 and the piston rod 5| to ward the left, The lever 93 is pivotallyy sup 60 ported upon .a pin 66 carried -by a link 61, the , other end of which is pivotally supported by a` 6Iy toward the left, and to rock the lever 63 in a clockwise direction to cause the jaws 54 and 65Y at the upper end thereof to grip the piston rod 5, through which the brakes are applied, and exert force thereon opposing the force exerted by the 25 pressure within the piston chamber 34, thus slightly decreasing the degree of application of the brakes below that corresponding to brake cylinder pressure. The degree of application of the brakes will be reduced both by reason of the 30 force exerted through the lever 63, and because of the reduction in the pressure of the fluid in the brake cylinder chamber 34 as. the result of the supply of fluid under pressure therefrom to the release mechanism 33. As the pressure builds 35 up in the piston chamber 44 and in the passage 43 to brake cylinder pressure, the weighted valve piston 55 is, at a predetermined pressure, also forced upwardly from its seat 55 against the bias of the spring 51, thus permitting the flow of ñuid 40 under pressure at brake cylinder pressure from the passage 43 through passage 58 to the piston chamber 46 to move the piston 41 against the bias of the spring 4I until the piston stem 49 engages the valve piston 39 and forces it to its seat 40. It will be noted that the area of the valve chamber 38, subject to piston chamber pressure after the valve piston 39 has been moved from its seat, is of considerably greater area than the central portion of the valve >piston 39 that is subject to brake cylinder pressure when the valve piston 39 is seated. As the result ofthe differ- Y ential force on the'valve piston 39 tending to urge it against the bias of the spring 4i when the 4 valve piston is seated and when it is unseated, a considerable drop in brake> cylinder pressure be low the valve necessary to unseat the valve piston 39 is required before the valve piston will again seat, due to the pressure ofthe spring 4I there 60 on. It will also be noted that Ythe area of the pin 98 on thenon-pressure head 33 of the brake piston 41, that is subject to'brake cylinder pres cylinder'. A 'spring 69 is provided, one end of sure after the valve piston 55 has become un which is connected to the lower end of the lever seated, is greater than the area of the valve 53 and the other rend of which is connected to the piston 39 that is subject to brake cylinder pres 65 non-pressure head 36 for urging the lever 53 in a ' sure in the valve chamber 38, so that, as soon as counterclockwise direction and forcing the piston pressure-builds up to a predetermined value in the piston chamber 45, the piston 41 acting "rod 9 Iv and the piston 45 toward the rightto per through the stem 49 will force the valve piston mitV free movement of the piston rod 6 in ac V cordance with changes in pressure in the piston 39 to its seat 49, and thereby cut off the supply Yof fluid under pressure from the brake cylinder 70 chamber 34. l ' ., VIn order to understand the operation of ap plicant’s invention, it should be borne in'mind that the permissible braking forces exerted by 75 the brake shoes uponthe car wheels are nor chamber 34 to the chamber 38 of the release mechanism 33, and prevent a further reduction in the pressure of the fluid in the brake cylinder chamber 34.l Fluid under pressure is released 75 3 gradually from the piston'cnamßer 46,`Ã> and from prede't'ermi'ned> vdegree »to Veiïect a corresponding the piston chamber 4'4ran`d the valve-‘chamber 38; application» ofthe brakes, the lever 63 -acting 'through the restricted passage 53"and¿port.52 through‘the jaws-64 and 65 exeïrts force on the to the atmosphere.. . » . Y» . _. It wur be noted that `when >the valve spis'toi‘r` 55 is unseated, permitting` fluid Vatm-brake ‘cylinder pressure to flow tothe piston ‘chamber '46, the full area of the valve piston is‘expos'ed to brake piston rod in 'a' brake releasing direction to re duce the degree of application of the brakes an C11 amount suilicient to prevent the wheels from sliding on the rails».w At the same time the pres sure ’of the fluid the brake Vcylinder is reduced cylinder pressure, so that, after the valve piston y by the supply of fluid under pressure from the is opened, the valve piston will b'e held open un#> brake cylinder to the release «mechanism 33, with 10 til fluid pressure acting on the f'valve piston has . the result that the ydegreeof brake application been» reduced to 'a vconsiderable degree 2less .than ' which 'the ¿brake cylinder can effect is correspond the degree of ñuid Íp‘ressure required to open the _ingly reduced.1 At a short time interval there valve. V-The effect of the differential-:areas be- ` after the lever ‘63 is` permitted to move in 4a tweenV the central porti‘onffof the valve piston 55,y that is subject to the pressure withinrthe pas’ sage 43, and the larger area o-Íf -th'e valvepiston, that is subject to- the pressure :within the valve chamber 54, is to require a ‘considerable vdecrease in pressure within the passage :43 and fv'alve ch‘am berV 54, after the valve piston has been unseated, below the value necessary to unseat it, 4before :the valve piston will again seat. _SW-hen, as `a result of the release of fluid under pressure tothe'at co'unterclockwise direction ïto release its grip upon 15 Ythe piston rod 6 and permit the >reapplimation »of mosphere through the restricted .passagei53 `in ïmeans of relieving the brake shoe -pressure will reduce in small increments the brakecylinder pressure and the 4brake shoe 'pressure resulting therefrom, so that, -as the speed of the train is reduced, 'and the coeflicient lof friction between the brake shoes "and 'the ‘car 'wheels is increased, 30 the brake cylinder pressure >will be ’reduced ‘at the Ípiston 4l, the pressure -in the valvechamber 54 has been reduced vsufñeient'ly’to permit the valve piston 55 to seat, the pressure in the piston chamber 44 will have permitted the piston '45 30 to be moved to its illustra-ted position by the spring _ 69, thus disengaging lthe jaws; 64 and 65 from the »piston rodY v6 and permitting. the brakes to be. applied to a value corresponding to the pressure Within the piston. chamber '34 fof the ' Asbrake the pressure cylinder within AI. the piston-chamber` « ' ' 'Y 46 the brakes tothe full value of brake cylinder pres sure„,which~-, aspointed out above, has been vre duced somewhat bythe release of vfluid therefrom. The frequency 'of operation oï the partial release 20 of¿ thebrakes is' such that high brake lcylinder pressure willnot continue -`for a sufficient length ofjti‘meftofeffect actual Wheel sliding 4but will beV reduced at 'the incipient stage of ’wheel sliding. ~ ' a rate to provide 'the 1maximum rate of decelera tion of the vehicle until a Alow vehicle speed is reached, when the brake cylinder pressure will have been reduced to such value that «the braking 35 Vforces will produce a smoothl stop. While one preferred embodiment of-my-inven decreases due to» the release ‘of fluid underpres sure through the restricted passage 53, theiorce tion has been illustrated land described, it will >be of the piston stem 49 against 'the valve :piston 39 Vapparent to those skilled in the lart ¿that many 40 is reduced, and the piston 41 and.stem«-r49 :are modifications `in the ïapparatus illustrated may moved by the force of ‘the spring 4l ‘against v,the ~ be made within 'the spirit of my ’invention >and l stop 48, as illustrated, thusjpermitting'the valve Iïdo not wish to‘be limited ’otherwise't'haniby'the piston 39 to again be unseated due to themes'.-v »scope of the'appended claims. sure withinïthe «piston chamber v34 ¿as >applied. to Having 'now described my -invention, ‘what nI the central smaller area Aof the valve piston 39> I claim'as new and desire to secure by-Letters Pat through passage 42, thus repeating the-cycle ofV ent, is: operation just above described, causing the ¿piston 1. Ina brake equipment for vehicles, 'a vbrake 45 -to be forced to the vleft to again/exert ~force` cylinder, means for supplying ‘fluid under :pres on the piston rod l6 `tending A»to ~move Yit 4'toward the right to decrease t-he brake shoe `pressure somewhat below that corresponding to brake’cyl-A inder pressure within Athe >piston Ichamber 34, 45 sure to said 'brake cylinder to apply the brakes, and means subjectlto brake cylinder pressure and operative upon a predetermined brake `cylinder pressure for effecting va partial -release :df `the while'the pressure ofthe -iluid in the ‘brake cyliri--` Vbraking force 'occasioned Vby the-brake >cylinder der chamber 34 is further reduced -by'the supply pressure for a short interval vof time, and for of fluid therefrom to the releasing mechanism33. thereafter interrupting said brake releasing force -Likewise, as the pressure withinr'the piston cham: ' toipermitfreapplication'of ‘the brakes'to a value . ber 44 builds iup ‘to a »value‘suñicienttoexertf corresponding -to brake'cylinderl‘pressure. ‘2.’ Ina brakelequipment for vehicles, a‘brake Vsubstantial force on the piston: 45, -the ¿pressure of fluid supplied from the‘brake‘cylinderthrough cylinden‘meansl for supplying iiuid under pres - the passage 43 will build up to a `value sufiicient ’ sure to saidgbrake cylinder to'apply=the brakes, 60 to force the valve piston >55 upwardly' from its l ` and means subject -to brake cylinder pressure and seat against the bias of the spring5'l -andreiïect operative upon a predetermined ‘brake -cylinder the supply of `fluid under pressure `»to thepiston pressure for effecting a partial 'release of 'the chamber 46 to again 'cause the seating-»of `the >braking force occasioned by .thebrake vcylinder pressure, and means for Vintermittentlyreducing valve pistonr 39.1 l, These cycles ~of operation are repeated until thepressurein the piston chamber 34 of the brake cylinder I has Vdecreased to yavalue depending upon the setting of the'spring 4l below‘which the fluid vat brake cylinder lpressure, vsupplied saidbrake cylinder pressure `in a step by step manner toiprevent the wheelsffrom sliding on the rails. ~ -, ' v ` 3. >In -a brake Aequipmentfor vehicles, 'a'brake cylinder, means -forl supplying -ñuid under -pres through the passage'42 to the Vseated area;of Y sureto said brake cylinder to apply-the brakes, valvepiston A3ilyis‘insuilicient to force the valve means subjectV to brake :cylinder pressure .and piston 39 from its seat 40. operative Aupon ¿a predetermined brake cylinder Y , Y -It will be noted 'that immediately after’the 3 pressure -for >effecting >a -reductionßin‘thelbraking brake cylinder‘pressure has ‘been `increased tofa force below that correspondingzto‘lbrake cylinder 4 pressure, meansfsubject to the operation of said last mentioned «means for aeffecting a predeter-A pressure to said pressure operated means, and means subject to the pressure inY said pressure mined reduction in brake cylinder> pressure and for effecting a reapplicationjof the brakes in ac of said braking force reducing means. « cordance with brake cylinder pressure. 4. In operated means for interrupting> the operation 10. In abrake equipment for vehicles, a brake ' brake equipment for vehicles, .a brake `cylinder, meansfor supplying fluidr under pres sure to said .brake cylinder to apply the brakes, means for preventing the sliding of the Wheels comprising means responsive to a predetermined brake cylinder pressure for effecting a reduction in the braking force below the value correspond ing to brake cylinder pressure, a reduction in lbrake cylinder pressure, and a full application of ” the brakes in accordance with the reduced brake cylinder, means for supplying fluid under pres sure to said brake cylinder,V to apply the brakes, means for reducing the sliding of the Wheelson the railsV comprising a pressure operated’brak _ing force reducingmeans for reducing >the degree l0 of application of the brakes below a value cor responding to the pressure on the brake cylinder pistoma weightedÍvalve` subject to .brake cylin ïder pressure foreifecting the supply of fluid un der pressure from said brake (cylinder to said 15 cylinder pressure.v pressure operated means, and means subject to . 5. In abrake equipment .for vehicles', a brakel the pressure irl-said pressure operated means fory cylinder, meansgfor supplying iiuid under pres surewto said brake cylinder to apply the brakes, from said brake cylinder and for gradually re leasing fluidrunder pressure from said pressurel means subject to Vbrake, _cylinder pressure andV operative upon a predetermined brake cylinder operated braking forcereducing means to effect pressure for effecting a recurring decrease in a reapplication >of the brakes in accordance with braking force belowthat corresponding to brake brake cylinder.- pressure. « cylinder Vpressure-¿ai reduction in brake cylinder pressure, and a reapplication of the brakes in ac-Y ` cordance with brake. cylinder pressure. 6. In a brake equipment for vehicles, a brake cylinder, means'for supplying fluid under pres sure to said brake cylinder tofapply the brakes, means for preventing wheel slipping comprising means for intermittently effecting a reduction in brake cylinderv pressure and for effecting an al ternate reduction in the braking force below brake cylinder pressure and a reapplication of the’brakes in accordance with the reduced brake Y cylinder pressure. 49 interrupting the 'flowA of fluid runder pressure v '7. In a brake equipment for vehicles, a brake cylinder, means for supplying fluid under pres sure to said brake cylinder to apply the brakes, a braking force reducing means subject to brake cylinder pressure and operative upon a brake cylinder vpressure above a predetermined value for effecting a 4reduction in braking force below that corresponding to brake cylinder'pressure, 4.5 means responsive >to the operation of said last Y. ,l ' Y V11. In a brake equipment-for vehicles, a brake cylinder, means for supplying fluid under pres 25 sure to said brake cylinder to apply the brakes, means forreducing the sliding of the wheels on the rails comprising a pressureoperated brak ing force reducing means for reducing the de grec of application of the brakes'below a valve 30 corresponding to the pressure on the brake cyl inder piston, a weighted valve'subject to brake cylinder pressure for effecting the supply of fluid' under pressure from said brake cylinder to said pressure operated means upon anincrease in brake cylinder pressure above a predetermined value, and means subject tothe pressure in said pressure operated means .for interrupting the operation of said braking force reducingV means and for effecting a reduction in brake cylinder pressure upon the increase in pressure in said pressure operated means above a predetermined value.V » .' ' . y. x . ' ' 12. Ina brake equipment for vehicles, a brake cylinder, means for supplying fluid under pres- , named means for effecting a reduction in brake v sure to said brake cylinder to apply the brakes, cylinder pressure and for` interrupting the op 50 eration of said braking force reducing means to permit a reapplication of the braking force to a valve corresponding to the reduced brake cyl inder pressure. . ' v 8. In a brake equipment for vehicles, a brake cylinder, means for supplying fluid under pressure means for reducing the sliding of the wheels on the rails comprising a pressure operated braking force reducing'means forY reducing the degree of application of the brakes below a value corre sponding to the pressure on the brake cyiinder . piston, a Weighted valvey subject to brake cylinder pressure for effecting the supply of fluid under to said brake cylinder to apply the' brakes, a brak ing force reducing means subject to brake cyl pressure from said ubrake cylinder to said pres sure operated means, a weighted valve subject inder pressure and operative upon a Ybrake cyl-V to the pressure in said pressure operated means inder pressure above a predetermined value for >forv effecting the _movement of said ñrst named effecting a recurring cycle of operation to effect weighted valve to close communication to said a reduction in braking force below that corre pressure operated means, and means for reduc sponding to brake cylinder pressure, a reduction ing the pressure in said pressure operated means 60 in brake Cylinder pressure, and the'interruption to permit a reapplication of the -brakes cor of the operation of said braking force reducing respondence with brake cylinder pressure. ' means Vto permit a reapplication of the braking 13.» lnV abrake equipment for vehicles, a brake fore-e to a value corresponding to the reduced A cylinder, means for supplying ñuid under pres Y 65 brake cylinder pressure. sure to said brake cylinder to applythe brakes, 9= In a’brake equipment for vehicles, a brake a braking force reducing meanssubject to brake cylinder, means for-‘supplying fluid underY pres cylinder pressure and operative upon a brake sure to said'brake cylinder to apply the brakes,` cylinder pressure abovera predetermined value means for reducing the sliding of the Wheels on for effecting a reduction in braking force below the‘rails comprising a pressure operated braking force reducing means for reducing the degree 'of' V,application of the brakesbelow a value corre spending to thepressure on the brake cylinder piston, a weighted valve subject to lic-rake cylinder 7.5 pressure»foreiîectingthe supply of ñuid under that correspondingr to brake „cylinder pressure - comprising a pressure operated means for op posing tl’ie effect of saidV brake cylinder pressure, valve means for effecting the’ supply Vof fluid under pressure thereto in 4accordance with brake cylinder pressure, and> means for, Veffecting a 75 5 2,132,913 partial, release of fluid under pressure therefrom" Y to Vinterrupt the operation of said braking _force reducing means. Y 14. In a brake equipment for vehicles, a brake cylinder, means for supplying fluid under pres sure to said brake cylinder to apply the brakes, a braking force reducing means subject to brake cylinder pressure and Aoperative upon‘ a Vbrake ¿17, In‘ a brake „equipment for vehicles, a 'brake cylinder, means for supplying fluid under pres sure toY said brake cylinder to‘apply the brakes, a braking force reducing >means forv reducing .the braking force below the value correspond ing> to brake vcylinder pressure, having a brake rreducing pressure chamber and a weighted valve Vresponsive to brake cylindery pressure above a predetermined _value for effecting the supply of cylinder pressure above a predetermined-value for effecting a reduction in braking force below l fluid under, pressurefrom said brake cylinder to that corresponding to brake cylinder pressure ' said chamber, apressure operated means having andl comprising pressure operated` means for opposing the effect of 'said brake cylinder pressure,1valve means for effecting the ‘supply Yof fluid under'pressure thereto in accordance a stem for urging said weighted valve to its seat, and means responsive to the pressure in said pressure chamber> above a predetermined value for Vsupplying :fluid under pressure from said withV the brake cylinder pressure, and means for pressurefvchamber to said pressure operated . 'effecting a partial release of ñuidunder pressure ~ means 4toeffecua’release of said braking force from said brake cylinder and from said pressure operated means toA eñect a reapplication of the 18.,In a fluid pressure brake, in combination, 20 brakes in Yaccordance lwith "the reduced. brake cylinder pressure. , A. ’ 15. In a brake equipment for vehicles, a, brake a brake cylinder,- a,brake_ cylinder piston there 20 in, means for supplying fluid under pressure to said brake cylinder, av piston, means for opera tively connecting said piston to the brake cyl sure to said brake cylinder to apply theibrakes, inder piston to oppose> the pressure on the rbrake a braking force reducing means for reducing ¿the , cylinder pistonby the fluid pressure acting on> 25 braking force below the value corresponding to saidopposing piston,'and means operated upon brake cylinder pressure and havingxa braking Va predetermined increase -in brake cylinder pres forcereducingpressure chamber, means respon-'î sure for >supplying fluid under pressure toßsaid' cylinder, means for supplying'fluid under pres- , 30 sive to brake cylinder pressure abovea predeter mined value for effecting the supply of'fluid opposing piston. ' ' . ' ‘ under pressure to said chamber at brake cylinder pressure,.pressure operated means for interrupt ing the supply of fluid under pressure to said 19. Inv a fluid pressure brake„in combination, a brake cylinderya brake cylinder piston there in, means-for supplying fluid under pressure to said brake cylinder, a piston, means for opera braking force reducing pressure chamber, means tivelyconnectlng said piston to the brake cylin 35 responsive to the pressure in said pressure cham- Y der piston <to oppose the pressure on the brake 35 ber‘above a predetermined Value for supplyingA > cylinder piston;A by the fluid pressure acting on fluid under pressure to‘VV said pressureoperated means, and means forV releasing fluid under pres- said opposing piston,»va1ve` meansy operated upon sure from said braking force reducing pressure 40 chamber and from said pressure operated means sure for'y supplying fluid under kpressure to said' to effect the release of said braking force reduc- ' av predetermined increase in brake cylinder pres opposingV piston, and means operated upon a pre 40 determinedzin‘crease vin `the pressure of fluid supplied> to‘said .opposing piston for operating ing means to» permit the reapplicationj of a brak ing force Vin accordance Withbrake’cylinder pres said pvalve meansto cut off the supply of fluid sure, and the‘release of said'pressure operated'> to 'said opposing piston. means to permitfurtheroperation of the means , responsive to brake cylinder vpressure for‘effect ing a subsequent operation of saidbraking force 20. InA añuid pressure brake, inr combination, a brake cylinder, means for supplying fluid un der.. pressure toe the brake cylinder, Y.mechanism operated upon a predetermined increase in brake 16. In` a brake equipment for`vehicles, a‘brake > cylinder pressure for reducing'the braking force cylinder, means for supplying 'fluid under pres eil‘ected by .the'increase'in brake cylinder pres sure to said brake cylinder to apply the brakes,` sure,r and means operative after a predetermined a braking force reducing means for.V reducing time intervalV for cutting said mechanism out of the braking force below the value corresponding action. >. ' reducing means. i ' ’ ' ~ ‘ to brake cylinderipressure having a brake re ' 21. Ina fluid pressure brake, in combination, a ducing> pressure and chamber, means responsive tobrake cylinder pressure above apredeterrnined value for effecting the supply of fluid'under brake cylinder, means for supplying fluid under pressure to the Vbrake cylinder, mechanism oper ated upon' a predetermined increase in brake cyl pressure from said brake cylinder‘t'o said >cham-> , inder pressure for interposing a force to oppose ber, pressure operated means Vfor’ interrupting the.` braking force set up by the increase in brakeV the supply or" fluid under’pressure to saidbrake cylinderY pressure, Hand means operated after a (30 predetermined timelinterval‘for relieving said reducing chamber, means responsive to the pres sure in said pressure chamber above a 'predeter-Ä mined value for supplying fluid under pressureV from said pressure chamber to said pressure op erated means, and means for. releasinggfluid under pressure from saidbrake reducing pres sureY chamber and from said pressure operated means to effect a release of said` braking force reducing means to permit a reapplication vof the braking force in correspondence with brake cylinder pressure, and a release of said pressure i opposing force. . ` . Í ` :ï 22. In aiñuid pressurebrake, in combination, va.'«lîirake cylindena piston in said'brake cylinder and operable on an increase in the'pressure of the fluid therein to exertiforc'e to effect an application of the brakes,>an ropposing piston `operative on an increase in the pressure of the fluid supplied thereto to exert force opposing the force exerted by saidbrake‘cylinder piston,`and'means subject to and operated on a. predetermined increase in operated means to permit further operation of' ’ the pressureof the fluid supplied to the'brake said means responsive to brake cylinder pressure for effecting a subsequent operation of said brak cylinder- to`supp1y fluid from the brake cylinder to said opposing piston to'l reduce the -braking ing force reducing means. force below the value corresponding to the brake ' ' 6 areas 13 cylinder pressure >and to also reduce vbrake cylin for thereafter releasing fluid under pressure from said pressure chamber to permit a reapplication 23. In a fluid pressure brake, in combination, a Y of the brakes in accordance with the reduced ap brake cylinder, a piston in said brake cylinder plication chamber pressure. ' der pressure. ' « ’ ' and operable on an increase in the pressure 0f -the fluid therein to exert force to effect an appli - 26. In a fluid pressure brake equipment for a l) vehicle having ra Wheel, in combination', a brake cation of the brakes, `an opposing piston operative y cylinder, a piston mounted in said brake Ycylin on'an lincrease in the pressure of the fluid sup der and'having an application chamber vat the plied’thereto to exert force opposingthe` force lO Aexerted by said brake cylinder piston, means sub ject to and operated on a predetermined increase ` in the pressure of the fluid supplied to the brake cylinder to supply ñuid from »the brake cylinder , to said opposing pistonv to reduce the braking force below the value corresponding'to the brake , cylinder pressure and to also reduce brake cyl inder pressure, and means subject to and ’operat ~ ed on a predetermined increase in the pressure of the fluid supplied to the opposing piston for cutting off the supply of fluid to said piston and for releasing fluid therefrom. 24. Ina vehicle fluid pressure brake equip face thereof, said piston beingoperable on an in crease in the pressure of the ñuid in said appli cation chamber to exert braking force von said Wheel to resistrotation thereof, the degree of braking force varying in accordance with the in crease in the‘pressure ofthe fluid’in said-appli cation chamber, means for supplying fluidA under pressure to said application chamber to increase the pressure therein Vto a valuevwhich Vmay be sufficient to produce braking force onV said Wheel to a degree to prevent rotation thereof and to thereafter cut off the supply of fluid under pres 20 sure to said application chamber', releasing means operative on an increase in the pressure of the ment,v in combination, brakingimeans, applica ñuid in'a pressure chamber t0 exert force 0p _tion means operative on an increase in the pres posing that of the brake cylinder piston, means sure of the-fluid in a pressure chamber to exert , for supplying ñuid under pressurefrom said ap 25 force to effectV an application'of saidY braking plication chamber to said _pressure chamber to means, means for supplying'fluid under pressure thereby reduce the pressure of the ñuid in Vthe to/said pressurechamber and to thereafter cut application chamber and reduce theV braking force created by said brake cylinder piston and toalso olf the supply of fluid under pressure thereto, re 30 leasing means 'op’erative’ on an increase in the cause the releasing means to create aforce op pressure ofthe fluid in a control chamber to ex posing thatof the brake cylinder piston and ert force-opposing said application means, and thereby cause vthe effective braking force pro duced by said brake cylinder piston to be re duced below the- value corresponding lto appli Y valve means for supplying fluid under pressure from said pressure chamber to saidcontrol cham ber, whereby the degree of application of said f braking' means is reduced by the reduction in the pressure `of the fluid in saidY pressure chamber Y and by operation of'said releasing means, said valve means-being thereafter operative to cut off the supply of fluid under pressure from said pres sure chamber to said control chamber and to re . lease lluid from said control chamber to elîect arreapplication of the braking means by said ap plication means to a degree Vdetermined by the cation chamber pressure, and ymeans for there after releasing fluid‘under pressure from said pressure chamber to permit a reapplication of the brakes in accordance with the reduced ap plication chamber pressure. f ` ' . 27. Vehicle brake apparatus comprising a brake a cylinder, brake control means operative to con trol kthe supply‘of fluid under pressure to and the release of fluid under pressure from the brake cylinder to effect Vapplication and release pressure of the fluid remaining in the pressure respectively of the brakes, means' providing a . chamber( chamber, means effective while said brake con .~ ‘ 25. In a fluid pressure brakeequipment for a vehicle having a Wheel, in combination, a brake 30 trol means'is conditionedto cause application ofVV the brakes forA causing fluid under pressure to cylinder, a’piston mounted in’said ‘brake cylin- . be supplied'from the brake cylinder to said cham der and having an applicationv chamber Hfat the Y ber to reduce brake cylinder pressurefand con- , face thereof,said piston being operable on an in sequéntly the degree of application of the brakes, crease in the pressure of the fluid 5in said appli-V Vand means responsive to the pressure yin said cation chamber to’exert braking. force varying chamber for exerting a force Yin opposition to in accordance with the increase inthe pressure brake cylinder pressure to further reduce the of the fluid in said application chamber, meansA for supplying fluid under pressure to saidv appli-cation chamber and to thereafter Vcut off ‘the sup# ply of' fluidunder pressure to said application chamber, releasing means operative on' an 'in effective degree of application of the brakes. 28. Vehicle brake apparatus comprising a brake l cylinder, brakeV control means operative to con trol the supply of‘iluid underY pressure to and the release of fluid under pressure from the brake crease‘in lthe pressure/of the fluid in a pressure ’ cylinder to effect application andVV release respec 60 chamber to exertforce opposing that of the brake tively of the -brakes, means providing a chamber, ' cylinder piston, means for releasing fluid ’under means automaticallyA effective while the brake pressureV from said application ïchamber and to controlmeans .is conditioned‘tov cause applica thereafter cut o'ffitherelease of fluid from said tion of the brakes for causing fluid under pres - chamber to` maintainY the pressure Vtherein at a lower value than that initially present therein to therebyreduce the braking force created by said brake 'cylinder piston, means for supplying fluid under pressure to ’said pressure chamber . concurrently with the release of ñuid from said ' application chamber to thereby cause'the effec tive braking force created by said‘brake cylinder piston to be reduced below‘the value correspond ing to application chamber pressure, and means sure to.V be supplied from vthe brake cylinder to said chamber to reduce the brake cylinder pres sure and consequently the ’degree of application of the brakes, and means responsive to the pres sure in? said chamber for exerting Va force in op position to brakekcylinder pressure to further re 70 duce the effective degree of application of the brakes.’ ' , BURTON s. AIKMAN.'