CA2213739A1 - Spring brake actuator having two-ply pressure plate assembly - Google Patents
Spring brake actuator having two-ply pressure plate assemblyInfo
- Publication number
- CA2213739A1 CA2213739A1 CA002213739A CA2213739A CA2213739A1 CA 2213739 A1 CA2213739 A1 CA 2213739A1 CA 002213739 A CA002213739 A CA 002213739A CA 2213739 A CA2213739 A CA 2213739A CA 2213739 A1 CA2213739 A1 CA 2213739A1
- Authority
- CA
- Canada
- Prior art keywords
- plate
- plate member
- push rod
- diameter
- actuating mechanism
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
- F16D65/00—Parts or details
- F16D65/14—Actuating mechanisms for brakes; Means for initiating operation at a predetermined position
- F16D65/28—Actuating mechanisms for brakes; Means for initiating operation at a predetermined position arranged apart from the brake
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
- B60T17/00—Component parts, details, or accessories of power brake systems not covered by groups B60T8/00, B60T13/00 or B60T15/00, or presenting other characteristic features
- B60T17/08—Brake cylinders other than ultimate actuators
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
- B60T17/00—Component parts, details, or accessories of power brake systems not covered by groups B60T8/00, B60T13/00 or B60T15/00, or presenting other characteristic features
- B60T17/08—Brake cylinders other than ultimate actuators
- B60T17/083—Combination of service brake actuators with spring loaded brake actuators
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16J—PISTONS; CYLINDERS; SEALINGS
- F16J3/00—Diaphragms; Bellows; Bellows pistons
- F16J3/02—Diaphragms
Abstract
A two-ply pressure plate (36) for use in an air brake system (10)for a vehicle, such as a bus, truck or the like, is shown. The two-ply pressure plate (36) includes a diaphragm plate (92) which abuts a diaphragm (32) of an air brake system (10) and a support plate (98) which abuts the rear surface of the diaphragm plate (92). A control rod (18) is welded to the support plate (98) and diphragm plate (92). Some form of mechanical or metallurgical interconnection between the support plate (98) and diaphragm plate (92) is formed in between the mounting point of the rod (18) and the outer perimeter of the smaller of the two plates.
Description
W O96/24516 PCTrUS95/01666 SPRING BR~KE ACTUATOR HAVING TWO-PLY
PRESSURE PLATE ASSEMBLY
BACKGROUND OF THE INVENTION
Field of the Invention This invention relates to a spring brake ~ctll~tor and, more particularly, to a spring brake ~r*l~tor having a two-ply pleS:iuiC plate ~ccçmhly Description of the Related Art An air brake system for a vehicle such as a bus, truck or the like, typically includes a brake shoe and drum assembly which is ~ctll~te~l by means of an ~ct~l~tor assembly operated by the selective application of a fluid such as co.ll~ressed air. Collvenlional air brake ~ tors have both a service brake ~rtnS~tor for ~ ting the brakes under normal driving conditions by the application of colllplessed air and an emergency or spring brake ~ctll~tor whichcauses ~ctll~tion of the brakes when air ~les~ule has been released. The emergency brake ~ct~l~tor inrllltl.os a strong colll~lession spring which forcesapplication of the brake when air is released. This is often referred to as the spring brake. Typically, the spring brake ~ct~l~tor is disposed in tandem with the service brake ~ct~l~tor.
When full air ples~ule is applied to the spring brake ~ctllz~tor, air ~les~ule acting against a diaphragm and a ~les~ule plate colll~resses the spring.
A spring brake ~çtn~tQr rod is either integral with the ~res~ure plate and held in a retracted position by the air pres~ulc or retracted by a return spring.
Depressing the brake pedal during normal driving operation introduces colll~ressed air into the service brake ~ctll~tor which, acting ~g~in.ct a diaphragm, causes a service brake pressure plate and ~tt~rhed push rod to be extended and the brakes to be applied with an application force proportional to the air pressure in the service brake ~ tor. In the event of a loss of air ples~ule or an intentiQnal e,~l~auslion of air from the spring brake ~ctll~tor, the brake will be mer-h~nicz3l1y activated by the force of a strong colll~ression spring acting on the spring brake ~tll~tor rod which, in turn, acts upon the service brake push rod to apply the brakes. Examples of known dual chamber spring W O96/24516 PCTrUS95/01666 brake assemblies inchlde U.S. Patent No. 5,105,727 to Bowyer, issued April 21, 1992, U.S. Patent No. 3,439,585 to Herrera, issued April 22, 1969; and U.S.
Patent No. 3,842,716 to Swander, Jr., issued October 22, 1974.
A typical serv-ice brake pressure plate assembly comprises a circular, flat 5 plate having the ~ tc r rod welded to the center of one s -rf~ce of the plate.The rod is welded to the plate by a collvc~ ion~l weld bead which çYte-n-lc around the perimeter of the base of the rod. FIG. 6 depicts an example of a known ~cS~ulc plate assembly. This ~ccemhly 200 comprises a circular l,res~ule plate 202 and an ~ tor rod 204 welded to one surface of the pressure plate 10 202 by a circular weld bead 206. The ~ctll~tor rod 204 is welded to the pressure plate 202 such that the longitll~lin~l aYis of the rod 204 is aligned with the central aYis of the circular pressure plate 202. Structurally, the largest loadsexperienced by the circular ~les~ule plate 202 are experienced adjacent the mounting point of the actuator rod 204. Less structural ~llcll~Lll is required 15 near the perimeter of the circular ples~ulc plate 202. Current ~JlCS~UlC plates are formed of Y4-inch-thick steel and s~ticf~ctQrily meet the structural requirements near the center of the plate. However, such plates far exceed the loads encountered ~cljz~cçnt the perimeter of each plate during n~
operation. Consequently, the thickness of the plate at the perimeter col~LiLuLes20 excess weight.
It is desirable to reduce the weight of the pressure plate while at the same time m~ i..g the structural integrity of the plate under higher stresses at the center thereof.
SUMMARY OF THE INVENTION
The spring brake ~ctll~tor accoldillg to the invention uvercollles the problems of the prior art by incorporating a 2-ply pressure plate which resist the shear forces and creates an integral bond between the ~hl~tor rod and pressure plate.
A brake ~tll~ting me~h~nicm accolding to the invention comprises a housing having first and second end walls defining a housing interior with an opening centrally disposed in the second end wall. An elastomeric diaphragm is suspended within the housing and divides the housing into a first chamber and a W O96/24S16 PCTAUS9~101666 second ~ h~llbcr. A ~res~urc plate ~ccemhly is received in the second chamber.
The plate assembly coll~ylises a push rod ~Yt~n~1in~ out of the housing through a centrally disposed opening and adapted to conn~-ct to a brake. The pressure plate assembly is reciprocally movable, res~onsive, in part, to the intro~lurtion 5 and eYh~1-ct of pres~uli~ed fluid to the first chamber. Accordi~g to one embo~limPnt of the invention, the ~ies~ure plate ~ccçmhly comprises a first plate and a second plate. The second plate abuts the first plate in face-to-face relationship with adjoining central portions. The push rod extends norm~11y from the first and second plates. The push rod has an end welded to the first 10 and second plates.
In another embodiment of the invention, the push rod is mounted to one of the central portion of the first plate and the first and second plates are secured to each other by at least one interconnçction located intermediate the central portions and the peripheral edges thereof to resist shear forces acting 15 between the first and second plates.
Preferably, the interconnection intermediate the central portions of the two plates comprises at least one emboccment formed in the first and second plates to mechanically connect the two plates together. Alternatively, the intermediate interconnection of the first and second plates is at least one spot20 weld.
The invention relates to a method of m~king a pressure plate ~csemhly for a brake actuator comprising the steps of placing a conductive metallic central portion of a first plate member in face to face relationship with a conductive metallic central portion of a second plate member. Flux material is 25 deposited in a recess in a conductive metallic proximal end of a push rod. The proximal end of the push rod is positioned on the central portion of the second plate and ~u~loul~ded with an incn1~ting collar. The first and second plates andthe push rod are placed in compression and a large pulse of electric ~;UllClll iS
applied to the first and second plates and the push rod to create a fusion zone 30 between the central portions of the plates and the push rod to weld the same together.
W O96/24S16 PCT~US9S/01666 BRIEF DESCRIPTION OF THE DRAWINGS
The invention will now be described with refere,lce to the drawings in which:
FIG. 1 is a cross sectional view of an air-operated brake ~rt~ ting S ~emhly having a two-ply pres~u,e plate accor-li"g to the invention;
FIG. 2 is a partial section~l view of a first embo~lim-o-nt of the two-ply ~,es~ure plate accordi,lg to the invention for use in the air-operated brake ~ct~l~ting assembly of FIG. 1.
FIG. 3 is a bottom plan view of the two-ply pressure plate;
FIG. 4 is a cross secti~n~ detailed view of the ~rt~-~tor rod and pressure plates prior to welding of the rod to the pressure plate;
FIG. 5 is sectional view of a second embodiment of the two-ply ~les~ule plate accoldi.lg to the invention; and FIG. 6 is a side elevational view of a prior art l"es~u,~ plate assembly.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to the drawings and to FIG. 1, in particular, a cross sectional view of an air-operated brake ~rtll~ting unit 10 having a general confi~-ration well known in the art is shown. The ~rt--~ting unit 10 comprises a service brakeportion 12 mounted in t~nclem to a spring brake or emergency brake portion 14.
20 A service brake push rod 18 çxtçn(lc from the service brake 12 for reciprocating motion and is provided with a clevis 20 which is adapted to connected to a collvell~ional brake (not shown) in a standard fashion. Reciprocating motion of the push rod 18 by the ~ct~ting unit 10 will cause the brake to be alternately applied and released.
The service brake portion 12 col"~,ises a pair of facing cup-shaped housing sections 21, 22, each having an oulw~Lrdly directed flanged edge 25, 26,respectively. The housing sections 21, 22 are clamped together at their fl~ng~
edges by a clamp 27 to form a serv-ice brake inner chamber 30. The peripheral edge of an elastomeric diaphragm 32 is ca~lu~ed between the opposed edges 25, 26, of the housing 21, 22 and suspended within the inner chamber 30. The service brake push rod 18 extends through a central aperture 34 in housing section 21 into the service brake chamber 30 where it termin~tes at a two-ply W O96/24516 PCT~US95/01666 S
yres~ure plate 36. A colllyress on spring 40 eYtentlc between the two-ply yres~ure plate 36 and the interior s~lrf~ce of the housing section 21. A spring seat 48 is disposed around the central opening 34 to receive the end of the c~Luylession spring 40 and retain it in position around the opening 34. The 5 spring 40 urges the yres~ule plate 36 and the service brake push rod 18 to a fully retracted position as seen in FIG. 1. MounLi.lg studs 46 are provided to the housing section 21 to mount the brake ~ tinp unit 10 onto an ayy,oyliate bracket (not shown).
To operate the service brake, colll~lessed air is introduced through an air 10 service port 38 formed in the housing section 22 to force the diaphragm 32 and the two-ply pressure plate 36 ~g~inct the force of the con~ression of the spring40 to ~ te the push rod 18. Ev~cn~tion openings 44 are provided in the housing section 21 to allow for the rapid eV~ tion of air from the inner chamber 30 as the yles~uli~ed air is introduced through the air service port 38.The spring brake 14 colllylises a pair of facing cup-shaped housing sections 51, 52 joined at their edges to define an inner chamber 53. Housing section 51 is provided with an oulw~Lrdly directed cilculllrcl~ntial flanged edge 54 which is received inside of a rolled peripheral edge 56 formed on the housingsection 52. An elastomeric diaphragm 58 is suspended within the spring brake 20 chamber 53 and is ca~luled at its peripheral edge between the edges 54, 56 ofthe opposed hDusing sections 51, 52. The portion of the chamber 53 between the diaphragm 58 and the housing section 51 forms an air chamber which is filled with co.ll~ressed air supplied through an air service port 59 in the housing section 51 when the emergency brake is in its norrnal, released position. An 25 ~ct~tor rod 60, aligned with push rod 18, has one end extending through a central aperture 64 formed in the end wall of the housing section 51. This end of the ~ct~-~tor rod 60 termin~tes in a reaction plate 62 which is received in acentral aperture 63 of the end wall of the housing section ~ of the service brake portion 12. The central aperture 64 is provided with a bearing 66 having 30 :-nml1~r recesses to accomrnodate a pair of O-rings 68. The bearing 66 forms a bearing surface and an air tight seal for the ~ct~tor rod 60.
The other end of the ~t~tor rod 60 extends through a centrally disposed aperture 81 in the diaphragm 58 and terrnin~tes in a spring brake CA 022l3739 l997-08-ll W O96/24516 PCTAUS9~/01666 es~ule plate 70 which eng~gt--s the spring brake colll~ression springs 72. The spring brake plcs~ule plate 70 co~ lises a subst~nti~lly flat portion 73 en~gingone end of the spring 72 and a tubular portion 74 extending generally aYially along the aYis of the spring 72. The tubular portion 74 iS press-fit onto an end5 portion of the ~c~l~tor rod 60 such that the spring brake pressure plate 70 and the rod 60 form an integral unit. The spring brake l~rcs~ule plate 70 may be formed of cast ~1-..";""...
During normal operation of the brake 10, the ~ch~tQr rod 60 will be in the fully withdrawn po.cition, as seen in FIG. 1, by means of colll~ressed air 10 which is ...~ ;..ed in the portion of the chamber 53 defined by the diaphragm58 and the housing section 51. When the colll~>ressed air is eYh~lsted~ the com~les~ion spring 72, one end of which eng~ges the outer end wall of t_e housing 52, forces the spring brake pressure plate 70 and integrally attached rod 60 in the direction of the brake push rod 18 of the service brake 12. The 15 housing section 22 of the service brake 12 and housing section 51 of the spring brake 14 are preferably steel shells ~tt~he~l to each other by means of a ~culllrerentially eYten-ling weld bead 76 or other suitable ~tt~çhment me~nc or can be an integral ~ casting. The force of the spring 72 causes the ~ct~l~tQr rod 60 to be eYtentle~l through the central opening 64 and causes the reaction plate 62 to apply a force to the diaphragm 32 and two-ply pressure plate 36 of the service brake. This action causes the service brake push rod 18 to be ~ct~l~te~l and the brake to be applied. When the brake is to be released, co~ lessed air is once again introduced in the space between the housing section 51 and diaphragm 58. The force of the colll~lessed air ~g~in~t the diaphragm 58 overcollles the co~ rc~ion force of the spring 72 and relulns the pres~ule plate 70 and rod 60 to the position seen in FIG. 1.
The ~chl~tor rod 60iS a hollow tube or rod provided with a central bore 61 to accommodate a brake release or caging bolt 78. The bolt 78 iS adapted to engage an end edge 80 of the tubular portion 74 of the spring brake l,ies~uie 30 plate 70 to m~int~in the spring 72 in a colll~ressed position whenever so desired. The bolt 78 may be used to m~nn~lly release the spring brake or to insure that the colll~les~ion spring 72 will remain fully compressed when maintenance functions are performed on the brake assembly. The bolt 78 iS
CA 022l3739 l997-08-ll W O96/24516 PCT~US95/01666 threaded and çng~ges a fixed, threaded opening or nut 77 affixed by welding or st~hn~ to the end wall of the housing section 52. A second nut or head 79 is fixedly attached to the threaded bolt such that the bolt may be rotated in the nut 77 by a commnn wrench or the like.
The two-ply ple~ule plate 36 acco~ g to the invention provides an equally strong mounting between the push rod 18 and the plate 36 than heletofole realized while enabling red~lce~l weight. As seen in FIGS. 3-5, a first embodiment of the ples~ule plate ~ccembly 36 coll-l~lises a diaphragm plate 92, a support plate 98 mounted to the diaphragm plate 92 and the service brake push rod 18 which is mounted to both the diaphragm plate 92 and support plate 98. The diaphragm plate 92 comprises a front surface 94, a rear surface 96 and an arcuate or rolled outer peripheral edge 97. The support plate 98 comprises a front surface 100, a rear snrf~ce 102 and a peripheral edge 103. It can be seen that the support plate 98 has a diameter s-lbst~nti~lly less than the diaphragm plate 92.
Preferably, the diaphragm plate 92 and support plate 98 are mounted adjacent to one another with the front surface 100 face to face with the rear surface 96, and secured to each other at multiple locations. The two plates are interconnected through a plurality of emboccment.c 106 which are formed in both plates intermediate the peripheral edge 103 of the support plate 98 and therod 18. The embo.ccment.c can be formed by cooperating male and female dies which deform the diaphragm plate 92 and support plate 98 such that a projection 108 extends rearwardly from the rear surface 102 of the support plate98 and a colle~onding recess 110 is formed on the front surface 94 of the diaphragm plate 92. The two plates have been deformed such that a projection 111 formed on the rear surface 96 of the diaphragm plate 92 is received in a complementary recess 112 formed on the front surface of the support plate 98.
- In the plefelled embodiment of the llles~ule plate ~ccemhly 36, the embossment 106 is flimencioned such that the depth of the recess 110 and the height of the 30 projection 108 is a~ .xi~tely one-half of the thickness of the diaphragm plate 92.
As seen in FIG. 3, the emboccmentc 106 are preferably arcuate and, if connected, would define a circle cnn~çntric with the perimeter of the diaphragm -CA 022l3739 l997-08-ll W O96/24516 PCTrUS95/01666 plate 92. The emboccm~-ntc 106 serve to ~rcvel,t the two plates from .chiftin~
with respect to one another by resicting shear forces acting between the two plates. In ~ lition, the emboccmentc 106 are spaced radially uuLwdrdly from the push rod 18 to distribute the load throughout the entire body of the ~u~po,l 5 plate 98. The interc~ ection of the emboccm~-ntc 106 of the plates 92, 98 resist the shear forces caused by warping or deflecting of the outer portions of the diaphragm plate 92 relative to the support plate 98. In order for the outer portion of the diaphragm plate to shear or deflect relative to the ~ul"~o,l plate 98, the rear surface 96 of the diaphragm plate 92 would have to slide across the10 front surface 100 of the support plate 98. The interconnection between the front and rear sllrf~ces reslllting from the emboscmentc 106 l~rGve"~ this sliding, shear movement. Therefore, the assembly will have the strength of the two plates where it is most needed, adjacent the mounting point of the push rod 18.
F~efe,dbly, the interconnections between the two plates are formed adjacent the perimeter of the smaller plate, in this case, the support plate 98. However, therelative position of the interconn~cti~ nc will depend largely upon the shear forces which are expected to be exerted on the pressure plate ~ccemhly. By interconnecting the two plates to one another ~dj~çnt the perimeter of the smaller plate, the .. ~xi... resict~nce to shear forces is achieved as a result of the greater shear area being available at the farthest interconnection point from the push rod 18.
The emboscmentc 106 also can act as a locator on the rear surface 102 of the su~l o,l plate 98 for the co",~lession spring 40 of the serv-ice brake 12. It is h~l~o~ldnt to keep the spring 40 centered around the longitll-lin~l axis of the push rod. The embossments 106 retain the co-.l~lession spring 40 in a particular orientation with respect to the push rod 18 as a result of abutting contact between the embossments 106 and the spring 40.
An alternative to the upsets described above would be an upset commercially known as the Tog-I~LockTY which is commercially available.
30 Similarly to the upset described above, the Tog-L-LockTY upset results in deform~tion of a portion of one of the plates into the other plate, thereby mechanically interconnecting these two plates.
_9_ The two plates 92, 98 are also connected to one another at the push rod 18. As seen in FIG. 2, the push rod 18, diaphragm plate 92 and support plate 98 are integrally welded to one another at a fusion zone 114 compAsing m~tçri~l from each of the separate elem-ontc The fusion zone 114 results from e 5 the integral welding, or bon-ling, of portions of the push rod 18, diaphragm plate 92 and ~ul~oll plate 98. The ~refelled welding method is a resistance welding operation wherein an end 116 of the push rod 18 along with portions of the support plate 98 and diaphragm plate 92 are welded to one another creating integral, metallurgical bonding between these three elem~n~c.
As seen in FIG. 4, the push rod 18, pAor to welding, has a recess 118 formed in the end 116 thereof. A suitable ilux mateAal 120 is packed into the recess 118. The flux 120 is col-ve..~inn~l in recict~n~e welding operations. After the flux 120 has been placed into the recess 118 of the control rod 18, a ceramic collar 124 is telescopically received on the rod 18 to abut the rear snrf:lce 102 of 15 the ~U~pUll plate 98 and ~ulloulld the base of the rod 18 which also is placed ~g~inct the rear surface 102. The support plate 98 is a~lopliately positioned zlg~in.ct the diaphragm plate 92, with central portions thereof 126, 128 ~dj~ce.nt each other and coaxial with the push rod 18. The collar 124 acts as a mold to m~int~in the desired shape of the rod 18 and plates 92, 98 in the fusion zone 20 114. After all elements are in place, a coLul,lcssion force is applied between the push rod 18 and diaphragm plate 92 and support plate 98. Preferably, 150 pounds of compression force is applied. After a sufficient col~ lessive force has been applied, a large pulse of electric ~;ullelll is passed through the diaphragm plate 92, support plate 98 and control rod 18. As the ~;ullclll passes through the 25 elements, resict~n~e to the CUllellt flow between the several elements m~nifçctc itself as heat. The combination of the large pulse of ~;ullellt, the pressure between the several elements and the abutting surfaces of the elements results - in fusing portions of the diaphragm plate 92, support plate 98 and push rod 18 to one another within the fusion zone 114. After the fusion zone has been 30 sufficiently cooled, the collar 124 is removed from the push rod 18 and the reslllting product is a twû-ply pressure plate accoldi~lg tû the invention wherein the surfaces of the two plates are integrally conn~cte~l to one another at points W O96/24516 PCTrUS95/01666 spaced from the push rod 18 and the central portions of the two plates are integrally welded to each other and to the push rod 18.
FIG. 5 shows a second embodiment of the service brake ~res~ule plate ~ccçmhly accoldill~ to the invention. In this emborlim~o-nt the pressure plate 5 :~cc~mhly 130 col~ ises the push rod 18, support plate 98 and diaphragm plate 92 which are centrally welded to one another at a fusion zone 114, preferably bythe previously described resict~nce welding process. Huw~ver, incte~-l Of m.och~niç~lly interconnecting the surfaces 96, 100 by emboccmentc as illustratedin FIGS. 2 and 3, the surfaces 96, 100 are welded to one another by a 10 collve..l;on~l spot welding process. Preferably, a circle of staggered spot welds 132 ~ulloullding the rod 18 secures the perimeter of the two plates to one another. The spot welds 132 resist the sliding, shear forces exerted on the two plates. For all embo~liment.c, it will be appre~te~l that each ply of the pressure plate can be formed of 10 gauge steel which results in .cignific~nt weight 15 redn~tion from prior art pressure plates.
The two-ply pressure plate ~ccçmhly accor.ling to the invention provides significant advantages over the conventional plate assemblies. First, the dual plate assembly provides the structural strength nececc~ry adjacent the push rod of the assembly while also elimin~ting material adjacent the perimeter of the 20 plate which is not structurally required. Therefore, the overall weight of the pressure plate assembly is reduced without s~rifi~ing any of the structural requirements.
Prior testing has shown that the force output curve of a brake can be r~ved by forming a lip or flange about the perimeter of the pressure plate 25 which bears against the diaphragm. The pres~ule plate assembly accoldhlg to the invention can be formed from two thinner pieces of steel which replace one thick piece of steel. A flange or lip can more easily and inexpensively be formed on the outer perimeter of a thin piece of steel than on a thick piece of steel. For example, it is extremely .liffi~llt and costly to attempt to form a 30 flange on a piece of ~4-inch steel. However, the same flange can be easily rolled into a 10-gage steel plate. Therefore, an u~loved force output curve can be achieved for a brake in~ln~ling a two-ply ~les~ure plate accor.ling to the W O96/24516 PCTrUS95/01666 invention through a less expensive and easier m~n-lf~ctllring process than was previously known in the prior art.
Re~con~hle variation and mo-lifir~tion are possible within the spirit of the fol~oi-lg specifi~tion and drawings without departing from the scope of the S invention.
PRESSURE PLATE ASSEMBLY
BACKGROUND OF THE INVENTION
Field of the Invention This invention relates to a spring brake ~ctll~tor and, more particularly, to a spring brake ~r*l~tor having a two-ply pleS:iuiC plate ~ccçmhly Description of the Related Art An air brake system for a vehicle such as a bus, truck or the like, typically includes a brake shoe and drum assembly which is ~ctll~te~l by means of an ~ct~l~tor assembly operated by the selective application of a fluid such as co.ll~ressed air. Collvenlional air brake ~ tors have both a service brake ~rtnS~tor for ~ ting the brakes under normal driving conditions by the application of colllplessed air and an emergency or spring brake ~ctll~tor whichcauses ~ctll~tion of the brakes when air ~les~ule has been released. The emergency brake ~ct~l~tor inrllltl.os a strong colll~lession spring which forcesapplication of the brake when air is released. This is often referred to as the spring brake. Typically, the spring brake ~ct~l~tor is disposed in tandem with the service brake ~ct~l~tor.
When full air ples~ule is applied to the spring brake ~ctllz~tor, air ~les~ule acting against a diaphragm and a ~les~ule plate colll~resses the spring.
A spring brake ~çtn~tQr rod is either integral with the ~res~ure plate and held in a retracted position by the air pres~ulc or retracted by a return spring.
Depressing the brake pedal during normal driving operation introduces colll~ressed air into the service brake ~ctll~tor which, acting ~g~in.ct a diaphragm, causes a service brake pressure plate and ~tt~rhed push rod to be extended and the brakes to be applied with an application force proportional to the air pressure in the service brake ~ tor. In the event of a loss of air ples~ule or an intentiQnal e,~l~auslion of air from the spring brake ~ctll~tor, the brake will be mer-h~nicz3l1y activated by the force of a strong colll~ression spring acting on the spring brake ~tll~tor rod which, in turn, acts upon the service brake push rod to apply the brakes. Examples of known dual chamber spring W O96/24516 PCTrUS95/01666 brake assemblies inchlde U.S. Patent No. 5,105,727 to Bowyer, issued April 21, 1992, U.S. Patent No. 3,439,585 to Herrera, issued April 22, 1969; and U.S.
Patent No. 3,842,716 to Swander, Jr., issued October 22, 1974.
A typical serv-ice brake pressure plate assembly comprises a circular, flat 5 plate having the ~ tc r rod welded to the center of one s -rf~ce of the plate.The rod is welded to the plate by a collvc~ ion~l weld bead which çYte-n-lc around the perimeter of the base of the rod. FIG. 6 depicts an example of a known ~cS~ulc plate assembly. This ~ccemhly 200 comprises a circular l,res~ule plate 202 and an ~ tor rod 204 welded to one surface of the pressure plate 10 202 by a circular weld bead 206. The ~ctll~tor rod 204 is welded to the pressure plate 202 such that the longitll~lin~l aYis of the rod 204 is aligned with the central aYis of the circular pressure plate 202. Structurally, the largest loadsexperienced by the circular ~les~ule plate 202 are experienced adjacent the mounting point of the actuator rod 204. Less structural ~llcll~Lll is required 15 near the perimeter of the circular ples~ulc plate 202. Current ~JlCS~UlC plates are formed of Y4-inch-thick steel and s~ticf~ctQrily meet the structural requirements near the center of the plate. However, such plates far exceed the loads encountered ~cljz~cçnt the perimeter of each plate during n~
operation. Consequently, the thickness of the plate at the perimeter col~LiLuLes20 excess weight.
It is desirable to reduce the weight of the pressure plate while at the same time m~ i..g the structural integrity of the plate under higher stresses at the center thereof.
SUMMARY OF THE INVENTION
The spring brake ~ctll~tor accoldillg to the invention uvercollles the problems of the prior art by incorporating a 2-ply pressure plate which resist the shear forces and creates an integral bond between the ~hl~tor rod and pressure plate.
A brake ~tll~ting me~h~nicm accolding to the invention comprises a housing having first and second end walls defining a housing interior with an opening centrally disposed in the second end wall. An elastomeric diaphragm is suspended within the housing and divides the housing into a first chamber and a W O96/24S16 PCTAUS9~101666 second ~ h~llbcr. A ~res~urc plate ~ccemhly is received in the second chamber.
The plate assembly coll~ylises a push rod ~Yt~n~1in~ out of the housing through a centrally disposed opening and adapted to conn~-ct to a brake. The pressure plate assembly is reciprocally movable, res~onsive, in part, to the intro~lurtion 5 and eYh~1-ct of pres~uli~ed fluid to the first chamber. Accordi~g to one embo~limPnt of the invention, the ~ies~ure plate ~ccçmhly comprises a first plate and a second plate. The second plate abuts the first plate in face-to-face relationship with adjoining central portions. The push rod extends norm~11y from the first and second plates. The push rod has an end welded to the first 10 and second plates.
In another embodiment of the invention, the push rod is mounted to one of the central portion of the first plate and the first and second plates are secured to each other by at least one interconnçction located intermediate the central portions and the peripheral edges thereof to resist shear forces acting 15 between the first and second plates.
Preferably, the interconnection intermediate the central portions of the two plates comprises at least one emboccment formed in the first and second plates to mechanically connect the two plates together. Alternatively, the intermediate interconnection of the first and second plates is at least one spot20 weld.
The invention relates to a method of m~king a pressure plate ~csemhly for a brake actuator comprising the steps of placing a conductive metallic central portion of a first plate member in face to face relationship with a conductive metallic central portion of a second plate member. Flux material is 25 deposited in a recess in a conductive metallic proximal end of a push rod. The proximal end of the push rod is positioned on the central portion of the second plate and ~u~loul~ded with an incn1~ting collar. The first and second plates andthe push rod are placed in compression and a large pulse of electric ~;UllClll iS
applied to the first and second plates and the push rod to create a fusion zone 30 between the central portions of the plates and the push rod to weld the same together.
W O96/24S16 PCT~US9S/01666 BRIEF DESCRIPTION OF THE DRAWINGS
The invention will now be described with refere,lce to the drawings in which:
FIG. 1 is a cross sectional view of an air-operated brake ~rt~ ting S ~emhly having a two-ply pres~u,e plate accor-li"g to the invention;
FIG. 2 is a partial section~l view of a first embo~lim-o-nt of the two-ply ~,es~ure plate accordi,lg to the invention for use in the air-operated brake ~ct~l~ting assembly of FIG. 1.
FIG. 3 is a bottom plan view of the two-ply pressure plate;
FIG. 4 is a cross secti~n~ detailed view of the ~rt~-~tor rod and pressure plates prior to welding of the rod to the pressure plate;
FIG. 5 is sectional view of a second embodiment of the two-ply ~les~ule plate accoldi.lg to the invention; and FIG. 6 is a side elevational view of a prior art l"es~u,~ plate assembly.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to the drawings and to FIG. 1, in particular, a cross sectional view of an air-operated brake ~rtll~ting unit 10 having a general confi~-ration well known in the art is shown. The ~rt--~ting unit 10 comprises a service brakeportion 12 mounted in t~nclem to a spring brake or emergency brake portion 14.
20 A service brake push rod 18 çxtçn(lc from the service brake 12 for reciprocating motion and is provided with a clevis 20 which is adapted to connected to a collvell~ional brake (not shown) in a standard fashion. Reciprocating motion of the push rod 18 by the ~ct~ting unit 10 will cause the brake to be alternately applied and released.
The service brake portion 12 col"~,ises a pair of facing cup-shaped housing sections 21, 22, each having an oulw~Lrdly directed flanged edge 25, 26,respectively. The housing sections 21, 22 are clamped together at their fl~ng~
edges by a clamp 27 to form a serv-ice brake inner chamber 30. The peripheral edge of an elastomeric diaphragm 32 is ca~lu~ed between the opposed edges 25, 26, of the housing 21, 22 and suspended within the inner chamber 30. The service brake push rod 18 extends through a central aperture 34 in housing section 21 into the service brake chamber 30 where it termin~tes at a two-ply W O96/24516 PCT~US95/01666 S
yres~ure plate 36. A colllyress on spring 40 eYtentlc between the two-ply yres~ure plate 36 and the interior s~lrf~ce of the housing section 21. A spring seat 48 is disposed around the central opening 34 to receive the end of the c~Luylession spring 40 and retain it in position around the opening 34. The 5 spring 40 urges the yres~ule plate 36 and the service brake push rod 18 to a fully retracted position as seen in FIG. 1. MounLi.lg studs 46 are provided to the housing section 21 to mount the brake ~ tinp unit 10 onto an ayy,oyliate bracket (not shown).
To operate the service brake, colll~lessed air is introduced through an air 10 service port 38 formed in the housing section 22 to force the diaphragm 32 and the two-ply pressure plate 36 ~g~inct the force of the con~ression of the spring40 to ~ te the push rod 18. Ev~cn~tion openings 44 are provided in the housing section 21 to allow for the rapid eV~ tion of air from the inner chamber 30 as the yles~uli~ed air is introduced through the air service port 38.The spring brake 14 colllylises a pair of facing cup-shaped housing sections 51, 52 joined at their edges to define an inner chamber 53. Housing section 51 is provided with an oulw~Lrdly directed cilculllrcl~ntial flanged edge 54 which is received inside of a rolled peripheral edge 56 formed on the housingsection 52. An elastomeric diaphragm 58 is suspended within the spring brake 20 chamber 53 and is ca~luled at its peripheral edge between the edges 54, 56 ofthe opposed hDusing sections 51, 52. The portion of the chamber 53 between the diaphragm 58 and the housing section 51 forms an air chamber which is filled with co.ll~ressed air supplied through an air service port 59 in the housing section 51 when the emergency brake is in its norrnal, released position. An 25 ~ct~tor rod 60, aligned with push rod 18, has one end extending through a central aperture 64 formed in the end wall of the housing section 51. This end of the ~ct~-~tor rod 60 termin~tes in a reaction plate 62 which is received in acentral aperture 63 of the end wall of the housing section ~ of the service brake portion 12. The central aperture 64 is provided with a bearing 66 having 30 :-nml1~r recesses to accomrnodate a pair of O-rings 68. The bearing 66 forms a bearing surface and an air tight seal for the ~ct~tor rod 60.
The other end of the ~t~tor rod 60 extends through a centrally disposed aperture 81 in the diaphragm 58 and terrnin~tes in a spring brake CA 022l3739 l997-08-ll W O96/24516 PCTAUS9~/01666 es~ule plate 70 which eng~gt--s the spring brake colll~ression springs 72. The spring brake plcs~ule plate 70 co~ lises a subst~nti~lly flat portion 73 en~gingone end of the spring 72 and a tubular portion 74 extending generally aYially along the aYis of the spring 72. The tubular portion 74 iS press-fit onto an end5 portion of the ~c~l~tor rod 60 such that the spring brake pressure plate 70 and the rod 60 form an integral unit. The spring brake l~rcs~ule plate 70 may be formed of cast ~1-..";""...
During normal operation of the brake 10, the ~ch~tQr rod 60 will be in the fully withdrawn po.cition, as seen in FIG. 1, by means of colll~ressed air 10 which is ...~ ;..ed in the portion of the chamber 53 defined by the diaphragm58 and the housing section 51. When the colll~>ressed air is eYh~lsted~ the com~les~ion spring 72, one end of which eng~ges the outer end wall of t_e housing 52, forces the spring brake pressure plate 70 and integrally attached rod 60 in the direction of the brake push rod 18 of the service brake 12. The 15 housing section 22 of the service brake 12 and housing section 51 of the spring brake 14 are preferably steel shells ~tt~he~l to each other by means of a ~culllrerentially eYten-ling weld bead 76 or other suitable ~tt~çhment me~nc or can be an integral ~ casting. The force of the spring 72 causes the ~ct~l~tQr rod 60 to be eYtentle~l through the central opening 64 and causes the reaction plate 62 to apply a force to the diaphragm 32 and two-ply pressure plate 36 of the service brake. This action causes the service brake push rod 18 to be ~ct~l~te~l and the brake to be applied. When the brake is to be released, co~ lessed air is once again introduced in the space between the housing section 51 and diaphragm 58. The force of the colll~lessed air ~g~in~t the diaphragm 58 overcollles the co~ rc~ion force of the spring 72 and relulns the pres~ule plate 70 and rod 60 to the position seen in FIG. 1.
The ~chl~tor rod 60iS a hollow tube or rod provided with a central bore 61 to accommodate a brake release or caging bolt 78. The bolt 78 iS adapted to engage an end edge 80 of the tubular portion 74 of the spring brake l,ies~uie 30 plate 70 to m~int~in the spring 72 in a colll~ressed position whenever so desired. The bolt 78 may be used to m~nn~lly release the spring brake or to insure that the colll~les~ion spring 72 will remain fully compressed when maintenance functions are performed on the brake assembly. The bolt 78 iS
CA 022l3739 l997-08-ll W O96/24516 PCT~US95/01666 threaded and çng~ges a fixed, threaded opening or nut 77 affixed by welding or st~hn~ to the end wall of the housing section 52. A second nut or head 79 is fixedly attached to the threaded bolt such that the bolt may be rotated in the nut 77 by a commnn wrench or the like.
The two-ply ple~ule plate 36 acco~ g to the invention provides an equally strong mounting between the push rod 18 and the plate 36 than heletofole realized while enabling red~lce~l weight. As seen in FIGS. 3-5, a first embodiment of the ples~ule plate ~ccembly 36 coll-l~lises a diaphragm plate 92, a support plate 98 mounted to the diaphragm plate 92 and the service brake push rod 18 which is mounted to both the diaphragm plate 92 and support plate 98. The diaphragm plate 92 comprises a front surface 94, a rear surface 96 and an arcuate or rolled outer peripheral edge 97. The support plate 98 comprises a front surface 100, a rear snrf~ce 102 and a peripheral edge 103. It can be seen that the support plate 98 has a diameter s-lbst~nti~lly less than the diaphragm plate 92.
Preferably, the diaphragm plate 92 and support plate 98 are mounted adjacent to one another with the front surface 100 face to face with the rear surface 96, and secured to each other at multiple locations. The two plates are interconnected through a plurality of emboccment.c 106 which are formed in both plates intermediate the peripheral edge 103 of the support plate 98 and therod 18. The embo.ccment.c can be formed by cooperating male and female dies which deform the diaphragm plate 92 and support plate 98 such that a projection 108 extends rearwardly from the rear surface 102 of the support plate98 and a colle~onding recess 110 is formed on the front surface 94 of the diaphragm plate 92. The two plates have been deformed such that a projection 111 formed on the rear surface 96 of the diaphragm plate 92 is received in a complementary recess 112 formed on the front surface of the support plate 98.
- In the plefelled embodiment of the llles~ule plate ~ccemhly 36, the embossment 106 is flimencioned such that the depth of the recess 110 and the height of the 30 projection 108 is a~ .xi~tely one-half of the thickness of the diaphragm plate 92.
As seen in FIG. 3, the emboccmentc 106 are preferably arcuate and, if connected, would define a circle cnn~çntric with the perimeter of the diaphragm -CA 022l3739 l997-08-ll W O96/24516 PCTrUS95/01666 plate 92. The emboccm~-ntc 106 serve to ~rcvel,t the two plates from .chiftin~
with respect to one another by resicting shear forces acting between the two plates. In ~ lition, the emboccmentc 106 are spaced radially uuLwdrdly from the push rod 18 to distribute the load throughout the entire body of the ~u~po,l 5 plate 98. The interc~ ection of the emboccm~-ntc 106 of the plates 92, 98 resist the shear forces caused by warping or deflecting of the outer portions of the diaphragm plate 92 relative to the support plate 98. In order for the outer portion of the diaphragm plate to shear or deflect relative to the ~ul"~o,l plate 98, the rear surface 96 of the diaphragm plate 92 would have to slide across the10 front surface 100 of the support plate 98. The interconnection between the front and rear sllrf~ces reslllting from the emboscmentc 106 l~rGve"~ this sliding, shear movement. Therefore, the assembly will have the strength of the two plates where it is most needed, adjacent the mounting point of the push rod 18.
F~efe,dbly, the interconnections between the two plates are formed adjacent the perimeter of the smaller plate, in this case, the support plate 98. However, therelative position of the interconn~cti~ nc will depend largely upon the shear forces which are expected to be exerted on the pressure plate ~ccemhly. By interconnecting the two plates to one another ~dj~çnt the perimeter of the smaller plate, the .. ~xi... resict~nce to shear forces is achieved as a result of the greater shear area being available at the farthest interconnection point from the push rod 18.
The emboscmentc 106 also can act as a locator on the rear surface 102 of the su~l o,l plate 98 for the co",~lession spring 40 of the serv-ice brake 12. It is h~l~o~ldnt to keep the spring 40 centered around the longitll-lin~l axis of the push rod. The embossments 106 retain the co-.l~lession spring 40 in a particular orientation with respect to the push rod 18 as a result of abutting contact between the embossments 106 and the spring 40.
An alternative to the upsets described above would be an upset commercially known as the Tog-I~LockTY which is commercially available.
30 Similarly to the upset described above, the Tog-L-LockTY upset results in deform~tion of a portion of one of the plates into the other plate, thereby mechanically interconnecting these two plates.
_9_ The two plates 92, 98 are also connected to one another at the push rod 18. As seen in FIG. 2, the push rod 18, diaphragm plate 92 and support plate 98 are integrally welded to one another at a fusion zone 114 compAsing m~tçri~l from each of the separate elem-ontc The fusion zone 114 results from e 5 the integral welding, or bon-ling, of portions of the push rod 18, diaphragm plate 92 and ~ul~oll plate 98. The ~refelled welding method is a resistance welding operation wherein an end 116 of the push rod 18 along with portions of the support plate 98 and diaphragm plate 92 are welded to one another creating integral, metallurgical bonding between these three elem~n~c.
As seen in FIG. 4, the push rod 18, pAor to welding, has a recess 118 formed in the end 116 thereof. A suitable ilux mateAal 120 is packed into the recess 118. The flux 120 is col-ve..~inn~l in recict~n~e welding operations. After the flux 120 has been placed into the recess 118 of the control rod 18, a ceramic collar 124 is telescopically received on the rod 18 to abut the rear snrf:lce 102 of 15 the ~U~pUll plate 98 and ~ulloulld the base of the rod 18 which also is placed ~g~inct the rear surface 102. The support plate 98 is a~lopliately positioned zlg~in.ct the diaphragm plate 92, with central portions thereof 126, 128 ~dj~ce.nt each other and coaxial with the push rod 18. The collar 124 acts as a mold to m~int~in the desired shape of the rod 18 and plates 92, 98 in the fusion zone 20 114. After all elements are in place, a coLul,lcssion force is applied between the push rod 18 and diaphragm plate 92 and support plate 98. Preferably, 150 pounds of compression force is applied. After a sufficient col~ lessive force has been applied, a large pulse of electric ~;ullelll is passed through the diaphragm plate 92, support plate 98 and control rod 18. As the ~;ullclll passes through the 25 elements, resict~n~e to the CUllellt flow between the several elements m~nifçctc itself as heat. The combination of the large pulse of ~;ullellt, the pressure between the several elements and the abutting surfaces of the elements results - in fusing portions of the diaphragm plate 92, support plate 98 and push rod 18 to one another within the fusion zone 114. After the fusion zone has been 30 sufficiently cooled, the collar 124 is removed from the push rod 18 and the reslllting product is a twû-ply pressure plate accoldi~lg tû the invention wherein the surfaces of the two plates are integrally conn~cte~l to one another at points W O96/24516 PCTrUS95/01666 spaced from the push rod 18 and the central portions of the two plates are integrally welded to each other and to the push rod 18.
FIG. 5 shows a second embodiment of the service brake ~res~ule plate ~ccçmhly accoldill~ to the invention. In this emborlim~o-nt the pressure plate 5 :~cc~mhly 130 col~ ises the push rod 18, support plate 98 and diaphragm plate 92 which are centrally welded to one another at a fusion zone 114, preferably bythe previously described resict~nce welding process. Huw~ver, incte~-l Of m.och~niç~lly interconnecting the surfaces 96, 100 by emboccmentc as illustratedin FIGS. 2 and 3, the surfaces 96, 100 are welded to one another by a 10 collve..l;on~l spot welding process. Preferably, a circle of staggered spot welds 132 ~ulloullding the rod 18 secures the perimeter of the two plates to one another. The spot welds 132 resist the sliding, shear forces exerted on the two plates. For all embo~liment.c, it will be appre~te~l that each ply of the pressure plate can be formed of 10 gauge steel which results in .cignific~nt weight 15 redn~tion from prior art pressure plates.
The two-ply pressure plate ~ccçmhly accor.ling to the invention provides significant advantages over the conventional plate assemblies. First, the dual plate assembly provides the structural strength nececc~ry adjacent the push rod of the assembly while also elimin~ting material adjacent the perimeter of the 20 plate which is not structurally required. Therefore, the overall weight of the pressure plate assembly is reduced without s~rifi~ing any of the structural requirements.
Prior testing has shown that the force output curve of a brake can be r~ved by forming a lip or flange about the perimeter of the pressure plate 25 which bears against the diaphragm. The pres~ule plate assembly accoldhlg to the invention can be formed from two thinner pieces of steel which replace one thick piece of steel. A flange or lip can more easily and inexpensively be formed on the outer perimeter of a thin piece of steel than on a thick piece of steel. For example, it is extremely .liffi~llt and costly to attempt to form a 30 flange on a piece of ~4-inch steel. However, the same flange can be easily rolled into a 10-gage steel plate. Therefore, an u~loved force output curve can be achieved for a brake in~ln~ling a two-ply ~les~ure plate accor.ling to the W O96/24516 PCTrUS95/01666 invention through a less expensive and easier m~n-lf~ctllring process than was previously known in the prior art.
Re~con~hle variation and mo-lifir~tion are possible within the spirit of the fol~oi-lg specifi~tion and drawings without departing from the scope of the S invention.
Claims (21)
1. In a brake actuating mechanism comprising a housing having first and second end walls defining a housing interior with an opening centrally disposed in the second end wall, an elastomeric diaphragm suspended within the housing and dividing the housing into a first chamber and a second chamber; a pressure plate assembly received in the second chamber, the pressure plate assembly comprising a push rod extending out of the housing through the centrally disposed opening and adapted to connect to a brake, the pressure plate assembly being reciprocally moveable, responsive in part to the introduction andexhaust of pressurized fluid to the first chamber, the improvement in the pressure plate assembly comprising:
a first plate member having a peripheral edge, a central portion and a diameter;
a second plate member having a peripheral edge, a central portion and a diameter less than the diameter of the first plate, the second plate member abutting the first plate member in face-to-face relationship with adjoining central portions and the push rod extending normally from the first and second plate members, the push rod having a proximal end thereof adjacent the central portions wherein the proximal end and the central portions of the first and second plate members are integrally welded to bond them to each other.
a first plate member having a peripheral edge, a central portion and a diameter;
a second plate member having a peripheral edge, a central portion and a diameter less than the diameter of the first plate, the second plate member abutting the first plate member in face-to-face relationship with adjoining central portions and the push rod extending normally from the first and second plate members, the push rod having a proximal end thereof adjacent the central portions wherein the proximal end and the central portions of the first and second plate members are integrally welded to bond them to each other.
2. A brake actuating mechanism according to claim 1 wherein the first and second plate members are further secured to each other by an interconnection located intermediate the central portions and the peripheral edges.
3. A brake actuating mechanism according to claim 2 wherein the interconnection comprises at least one spot weld between the first and second plate members.
4. A brake actuating mechanism according to claim 2 further comprising a plurality of interconnections between the first and second plate members.
5. A brake actuating mechanism according to claim 4 wherein the interconnections are spaced intermittently about the central portions of the first and second plate members in a circular pattern.
6. A brake actuating mechanism according to claim 5 wherein the interconnections are adjacent the peripheral edge of the second plate member.
7. A brake actuating mechanism according to claim 1 wherein the first plate member is circular and has a first diameter and the second plate member is circular and has a second diameter and the push rod is circular in cross section and has a third diameter, the first diameter being greater than the second diameter which is, in turn, greater than the third diameter.
8. A brake actuating mechanism according to claim 2 wherein the interconnection comprises at least one embossment formed in the first and second plate members to deform the members such that they are mechanically connected to one another.
9. A brake actuating mechanism according to claim 8 wherein the at least one embossment is arcuate along a plane parallel to the plane of the second plate member.
10. A brake actuating mechanism according to claim 9 and further comprising multiple embossments staggered intermittently about the central portions of the first and second plate members in a circular pattern.
11. In a brake actuating mechanism comprising a housing having first and second end walls defining a housing interior with an opening centrally disposed in the second end wall, an elastomeric diaphragm suspended within the housing and dividing the housing into a first chamber and a second chamber; a pressure plate assembly received in the second chamber, the pressure plate assembly comprising a push rod extending out of the housing through the centrally disposed opening and adapted to connect to a brake, the pressure plateassembly being reciprocally moveable, responsive in part to the introduction andexhaust of pressurized fluid to the first chamber, the improvement in the pressure plate assembly comprising:
a first plate member having a peripheral edge, a central portion and a diameter; and a second plate member having a peripheral edge, a central portion and a diameter less than the diameter of the first plate, the push rod being mounted to one of the central portions and extending normally therefrom wherein the first and second plate members are secured to each other by at least one interconnection located intermediate the central portions and the peripheral edges to resist shear forces acting between the first and second plate members.
a first plate member having a peripheral edge, a central portion and a diameter; and a second plate member having a peripheral edge, a central portion and a diameter less than the diameter of the first plate, the push rod being mounted to one of the central portions and extending normally therefrom wherein the first and second plate members are secured to each other by at least one interconnection located intermediate the central portions and the peripheral edges to resist shear forces acting between the first and second plate members.
12. A brake actuating mechanism according to claim 11 wherein the at least one interconnection comprises a spot weld between the first and second plate members.
13. A brake actuating mechanism according to claim 11 wherein the at least one interconnection comprises a plurality of spot welds between the first and second plates.
14. A brake actuating mechanism according to claim 13 wherein the spot welds are spaced intermittently about the central portions of the first and second plate members in a circular pattern.
15. A brake actuating mechanism according to claim 14 wherein the spot welds are adjacent the peripheral edge of the second plate member.
16. A brake actuating mechanism according to claim 11 wherein the interconnection comprises at least one embossment formed in the first and second plate members to deform the members such that they are mechanically connected to one another.
17. A brake actuating mechanism according to claim 16 wherein the at least one embossment is arcuate along a plane parallel to the plane of the second plate member.
18. A brake actuating mechanism according to claim 16 and further comprising multiple embossments staggered intermittently about the central portions of the first and second plate members in a circular pattern.
19. A pressure plate assembly for a brake actuator comprising:
a push rod having a proximal end;
a first plate member having a peripheral edge, a central portion and a diameter;
a second plate member having a peripheral edge, a central portion and a diameter less than the first plate member diameter, the second plate member abutting the first plate member in face to face relationship with adjoining central portions and the push rod extending normally from the first and second plate members, the proximal end of the push rod being adjacent the central portions wherein the proximal end and the central portions are integrally weldedto bond them to each other.
a push rod having a proximal end;
a first plate member having a peripheral edge, a central portion and a diameter;
a second plate member having a peripheral edge, a central portion and a diameter less than the first plate member diameter, the second plate member abutting the first plate member in face to face relationship with adjoining central portions and the push rod extending normally from the first and second plate members, the proximal end of the push rod being adjacent the central portions wherein the proximal end and the central portions are integrally weldedto bond them to each other.
20. A pressure plate assembly for a brake actuator comprising:
a first plate member having a peripheral edge, a central portion and a diameter; and a second plate member having a peripheral edge, a central portion and a diameter less than the first diameter, the push rod being mounted to at least one of the central portions and extending normally therefrom wherein the first and second plate members are secured to each other by at least one interconnection located intermediate the central portions and the peripheral edges whereby to resist shear forces acting between the first and second plate members.
a first plate member having a peripheral edge, a central portion and a diameter; and a second plate member having a peripheral edge, a central portion and a diameter less than the first diameter, the push rod being mounted to at least one of the central portions and extending normally therefrom wherein the first and second plate members are secured to each other by at least one interconnection located intermediate the central portions and the peripheral edges whereby to resist shear forces acting between the first and second plate members.
21. A method of making a pressure plate assembly for a brake actuator comprising the steps of:
providing a metallic first plate member having a central portion and a diameter;
providing a metallic second plate member having a central portion and a diameter less than the first plate diameter;
placing the conductive metallic central portion of the first plate member in face to face relationship with the conductive metallic central portion of thesecond plate member;
depositing flux material in a recess in a conductive metallic proximal end of a push rod;
abutting the proximal end to a central portion of the second plate member and placing a non-conductive collar around the push rod at the second plate member;
placing the first and second plate members and the push rod in compression; and applying a welding pulse of electric current to the first and second plate members and the push rod to fuse the central portions of the plate members and the push rod to each other.
providing a metallic first plate member having a central portion and a diameter;
providing a metallic second plate member having a central portion and a diameter less than the first plate diameter;
placing the conductive metallic central portion of the first plate member in face to face relationship with the conductive metallic central portion of thesecond plate member;
depositing flux material in a recess in a conductive metallic proximal end of a push rod;
abutting the proximal end to a central portion of the second plate member and placing a non-conductive collar around the push rod at the second plate member;
placing the first and second plate members and the push rod in compression; and applying a welding pulse of electric current to the first and second plate members and the push rod to fuse the central portions of the plate members and the push rod to each other.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002213739A CA2213739A1 (en) | 1995-02-10 | 1995-02-10 | Spring brake actuator having two-ply pressure plate assembly |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002213739A CA2213739A1 (en) | 1995-02-10 | 1995-02-10 | Spring brake actuator having two-ply pressure plate assembly |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2213739A1 true CA2213739A1 (en) | 1996-08-15 |
Family
ID=4161327
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002213739A Abandoned CA2213739A1 (en) | 1995-02-10 | 1995-02-10 | Spring brake actuator having two-ply pressure plate assembly |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2213739A1 (en) |
-
1995
- 1995-02-10 CA CA002213739A patent/CA2213739A1/en not_active Abandoned
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Discontinued |