CA1190340A - Friction materials for railroad brake shoes - Google Patents
Friction materials for railroad brake shoesInfo
- Publication number
- CA1190340A CA1190340A CA000410889A CA410889A CA1190340A CA 1190340 A CA1190340 A CA 1190340A CA 000410889 A CA000410889 A CA 000410889A CA 410889 A CA410889 A CA 410889A CA 1190340 A CA1190340 A CA 1190340A
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- Canada
- Prior art keywords
- composition
- volume
- friction material
- friction
- component
- 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.)
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- Braking Arrangements (AREA)
Abstract
ABSTRACT
A railroad brake shoe composition free of fiber reinforcement comprising, in percent by weight:
Phenolic Resin Binder; 1-15%
Carbonaceous Component: 30-60%
Organic Component: 15-30%
Inorganic Component: 5-35%
Friction Modifiers: 1-15%
Additive: 1 - 7%
A railroad brake shoe composition free of fiber reinforcement comprising, in percent by weight:
Phenolic Resin Binder; 1-15%
Carbonaceous Component: 30-60%
Organic Component: 15-30%
Inorganic Component: 5-35%
Friction Modifiers: 1-15%
Additive: 1 - 7%
Description
BACKGROUND 0~ THE INV~NTION
The invent;on herein relates to friction materials for brakes suitable for railroad service.
5Over the years a number of different types of composition railroad brake shoes have been described. These have normally been composed of a ~ubber and/or resin matrix heavily reinforced with asbes~os fiber and containing lead in the form of elemental lead and/or lead oxides and friction modifiers such flS iron chromite, 10silicon carbide and the like as critical components. Typical compositions have been describecl in U.S. Pat. Nos. 2,686,140;
The invent;on herein relates to friction materials for brakes suitable for railroad service.
5Over the years a number of different types of composition railroad brake shoes have been described. These have normally been composed of a ~ubber and/or resin matrix heavily reinforced with asbes~os fiber and containing lead in the form of elemental lead and/or lead oxides and friction modifiers such flS iron chromite, 10silicon carbide and the like as critical components. Typical compositions have been describecl in U.S. Pat. Nos. 2,686,140;
2,861,964; 3,152,099; 3,390,1139 l,832,325 3,959,194 and 4,]78,278.
Many of the materials described in the afore-mentioned patents have enjoyed widespread com~ercial success as railroad brake shoe 15compositions under the trademark COBRA. However, environmental and health concerns have led purchasers and therefore manufacturers to seek friction material compositions which contain neither asbestos fiber nor lead metal or its compounds. Recently, a composition containing little or no lead was disclosed. This was found to be 20quite advantageous in reducing wheel wear, particularly where softer steel wheels are used. See the aforesaid U.S. Pat. No. 3,959,194.
Efforts to eliminate asbestos fiber from the brake shoe compositions have been beset with major difficulties, primarily because the asbestos fiber contributed a unigue combination of reinforcement and 25thermal properties to the compositions. During service application brake shoes under~o significant physical stresses and also experience substantial temperature increases, often reaching peak t0mperatures in excess of 800~. Previously, fibrous materials other than asbestos such as certain or~anic fibers, steel fibers and 30combinations of steel fiber and metal grit have been found suitable to adeguately withstand the thermal and physical forces involved in railraod service.
Conventional AAR (Association of American Railroads) service for standard freight cars constitutes the large majority of 35the uses of friction materials and therefore many of the previous compositions were directed to such end useO Conseguently, a basic friction material composition for molcled brake shoes which is ~?~
I.c~
nsbestos-free and suitable for ~Ise in AAR service has been sollght, which woulcl meet the service re(luirements and be economical to manufacture.
BRI~F SUMMARY OF TH~ INVENTION
The invention herein i8 a molded fiber reinforcement-free friction material sui~able for railroad use which comprises~ in percent by volume:
Phenolic Resin Binder: 2-15%
Carbonaceous Component: 30-60%
Qrganic Component: 15-30~
Inorganic Component: 5-35%
Friction ~odifiera 1-15~
Additives: 1- 7%
In the pre~erred embodiments the composition may also contain from 5~ to 10~ by volume of friction moclifiers and from 5 up 10% by volume of phenolic resin binder; the carbonaceous component 30-50~ by volume and the inorganic component from 15% to 25% by volume and the organic component from 20~ to 25~ by volume.
D~TAIL~D DESCRIPTION AND PREFERRED EMBODIMENTS
The product of this invention is used in various types of railroad services which are categorized on the ba~is of the contact pressure which is applied across the face of the brake shoe during typical brake application. In service the actual pressures will depend on the type of railroad eguipment on which the brake is used, whether li~ht to emergency brake application is considered, and similar factors. The distinctions, however, are evident and will be clearly understood by those skilled in the art. In addition, AAR
service and heavy duty service commonly employ tread brakes as contrasted to disc brakes.
It is readily apparent from the foregoing that any particular composition selected for AAR use must have good thermal properties as ~ell as undereoing an evaluation of the effect the material will have in use on the metal wheel. These factors and others combine to ma~e the selection of components more of an art than a precise science. Small changes in tha proportion of one component with respect to another can produce considerable differences in the f;nal performance of the brake shoe. For example some combinations of materials ~hile e~hibitin~ ~ood friction chflracteristics in use may prove to be too hard on the metal railroad wheel to be satisfactory for long term use.
With thes~ many considerations and others in mind the composition of the present invention has surprisin~ly been found to exhibit the desired characteristics ~or a molded brake shoe friction material to be a satisfactory substitute for asbestos or other fiber reinforced materials in railroad service.
The first and largest component i~ the present composition 0 i9 an or~anic component which consists of a rubber component bonded together with a phenolic resin. The binder component and rubber matrix are the vehicles in which the other components are embedded.
The or~,anic component may contain mixtures of natural or synthetic rubber, to~ether with e].astomeric materials or a phenolic resin which may be vulcanized or otherwise cured to form a hard matrix for the remaining components. Of the rubbers preferred are the butyl rubbers, styrene-butadiene rubbers or nitrile rubbers. A number of varieties of the various natural or synthetic rubbers and phenolic resins are readily available and are widely described in the litsrature. Numerous rubbers are described in the Vanderbilt Rubber Handbook published by the R. T. Vanderbilt Company in 1968.
Phenolic resins ~enerally applicable for use in the present invention are described in the Modern Plastics Encyclopedia, Vol. 4, No. 10 (1970~1971). Cashew nut shell resins are preferred, primarily due to their excellent bondin~ and heat resistant properties. Such resins and their method or preparation are discussed in U.S. Patent Nos. 2,686,140 and 2,861,964. The or~anic component may in some embodiments be composed entirely of rubber, although most preferably the or~anic component will comprise a mixture of rubbers and phenolic resin~
Tha components listed herein are variously measured as percent by volume rather than the more common percent by weight, except where noted. This i9 done because the volume percenta~e reflects the physical properties of a given shape and size of brake shoe despite variations in the actual chemical composition of the shoe, since in brakin~ service an important factor is the amount of each material which is exposed at the braking surface which is in ~' ~.. ..
contact with the wheel tread. It also simpl;fies the ~escription of the material of the present invention in that it avoids the necessity Eor recalculation of components to account for varying densities of materials selected, such as in the organlc component.
The second component of the composition and one of the key components in any friction composition for brake shoes are the friction modifying a~ents describecl more fully hereinafteI.
A further component of the present composition will be inorganic fillers. These may be fl wide variety o~ granulated inorganic materials which clo not substantially affect the friction properties of the composition, but are rather used to fill out the composi~ion and rectuce the necessity for usin~ more of the expensive organic component. In addition, they also provide thermal properties to some degree, in that they serve as heat sinks.
Typical of the materials which may be used include alumina, barytes, silica, iron oxides, whiting, talc, diatomite9 clays and the like as well as mixtures of these various materials. Particle sizes will normally be in the ran~e of from 4 to 75 microns. The inor~anic fillers will normallg be present as from 5 to 35 percent by volume, preferably 15 to 25 percent by volume of the composition. In the present invention it is important that the inorganic filler component contains neither asbestos fiber nor lead metal or lead compounds.
The third component of the present composition is a carbonaceous component which is composed of carbon particles in any of a variety of forms, such as carbon black, carbon flour, graphite or gound anthracite. A sin~le material such as carbon black or mixtures of the various carbon-containin~ materials may be used.
This component will normally be present in from 30 to 60 volume percent, preferably 30 to 50 volume percent. Normall~ the particle size of the carbonaceous particles will be in the range from .02 to 150 microns. These materials have been and are incorporated in friction materials for several reasons includln~ color, to provide resistance to U.V. degradation of the polymerized materials, reinforcement of the cured rubber component, and the like.
The final materials required in the present invention are "additives" used to volcanize, cure or otherwise modify the rubbers ,~ . . .
~,~ . ..
--5~
and resln~, in the or~anic component. These will naturally vary depend-lng upon the nature of the particular or~anic component used, and the fina] physical properties sought but in general will include mAterials such as sulsphur, zinc oxide, thiazoles, sulfenamides, dithiocarbamates, pero~ides, anti-oxidants, retarders and other processin~ aids. A wide variety of such materials are described in the patent literature ancl the above-mentioned Vanderbilt Rubber Handbook. l'he aclditives ~ill be present as from about 1 to 7 volume percent, preferably 2 to 4 volume percent.
The composition therefore may contain in the cateeories described: cashew nut shell resin and friction modi~iers such as those inorganic materiflls which substantially affect the friction properties of the material. For the purposes of this invention, it will be considered that such friction modifiers are commonly minerals or ceramics havin~ a ~ohs hardness or ~reater than 5.
Typical of such materials are silicon carbide, zircon, garnet, iron chromite and similar materials. The friction modifiers will be in the form of granules having particle sizes in the ran~e from about 0.05 to 200 microns. The friction modifiers will be present as up to 15% volume percent, preferably 5~ to 10% volume percent, of the composition. While the friction modifiers employed herein have been found to have utility in varying amounts in other bra~e shoe compositions includin~ asbestos-reinforced friction compositions and compositions containing steel fibars alone or in combination with metal particles or "grit", the individual use in the amounts disclosed in a brake shoe composition havin~ no reinforcing fiber is somewhat surprising. It will be evident to those skilled in the art from the descriptions of the examples below how best to mix and otherwise formlllate the composikions of the present invention.
Additional descriptions of various types of processin~ equipment including mixers and molds may be found in Stern, ubber: Natural and Synthetic (2d en. 1~67) and Rubber World, ~achinery and ~g~ _nt for Rubber and Plastics (2d edn, 1963) and the patent literature.
The followin~ mo].ded brake compositions is ~ preferred embodiment of this invention, with al:L components listed as percent by weight and by volume:
--6~
Ex~ e I
~ BY WEIGHT ~ BY VOLUNE
Crumb Rubber with 10~ tfllc 12.74 23.36 ~ubbermakers' Sulfur0.51 0.45 TMTD Rubber Accelerator0,25 0.33 MBT Rubber Accelerator0.25 0.31 Antio~idant 0.].3 0.22 Ste~ric Acid 0.13 0.2~
Zinc Oxide 0.64 0.21 Carbon Black Powder 9.17 9.33 Carbon Flour lO.]9 9.33 Iron Chromite 14.0l 5.81 Red Iron Oxide 9.94 3.83 Silicon Cflrbide Nicrogrit 0.64 0.36 Carbon Base Filler 7.39 9.21 Rubbermakers' Hard Clayl8.85 13~39 Hard Rubber Dust 6.37 8.58 ~ineral Rubb0r 3.18 5.61 Liquid Cashew Nut Resin5.lO 9.48 Hexamethylenetetramine0.51 0.91 Total lOO.OO lOO.OO
Certain modifications in the foregoirlg composition can be made without losing the overall advantages of the molded friction material of the present invention. For example the antio~idant can be eliminated altogether as well as the stearic acid where unnecessflry in the molding procesfi. Variations such as these are commonly made in such formulations and can be made in practice without deleteriously affecting the advantages provided by the overall composition.
The important contribution described herein is that a friction co~position as described herein can be satisfactory for AAR
service without the presence of reinforcing fiber of any kind in a brake shoe tread material which pflsses the ob~ective tests and other requirements for AA~ service. The ~mounts of friction modifying agents, additives and processing and other aids can be Adjusted by one skilled ln the art to achieve the desired results.
"~,'~' The invantion ;~ therQîor~ only limit~d by the scope o~ the appended c 1 a im~ .
Many of the materials described in the afore-mentioned patents have enjoyed widespread com~ercial success as railroad brake shoe 15compositions under the trademark COBRA. However, environmental and health concerns have led purchasers and therefore manufacturers to seek friction material compositions which contain neither asbestos fiber nor lead metal or its compounds. Recently, a composition containing little or no lead was disclosed. This was found to be 20quite advantageous in reducing wheel wear, particularly where softer steel wheels are used. See the aforesaid U.S. Pat. No. 3,959,194.
Efforts to eliminate asbestos fiber from the brake shoe compositions have been beset with major difficulties, primarily because the asbestos fiber contributed a unigue combination of reinforcement and 25thermal properties to the compositions. During service application brake shoes under~o significant physical stresses and also experience substantial temperature increases, often reaching peak t0mperatures in excess of 800~. Previously, fibrous materials other than asbestos such as certain or~anic fibers, steel fibers and 30combinations of steel fiber and metal grit have been found suitable to adeguately withstand the thermal and physical forces involved in railraod service.
Conventional AAR (Association of American Railroads) service for standard freight cars constitutes the large majority of 35the uses of friction materials and therefore many of the previous compositions were directed to such end useO Conseguently, a basic friction material composition for molcled brake shoes which is ~?~
I.c~
nsbestos-free and suitable for ~Ise in AAR service has been sollght, which woulcl meet the service re(luirements and be economical to manufacture.
BRI~F SUMMARY OF TH~ INVENTION
The invention herein i8 a molded fiber reinforcement-free friction material sui~able for railroad use which comprises~ in percent by volume:
Phenolic Resin Binder: 2-15%
Carbonaceous Component: 30-60%
Qrganic Component: 15-30~
Inorganic Component: 5-35%
Friction ~odifiera 1-15~
Additives: 1- 7%
In the pre~erred embodiments the composition may also contain from 5~ to 10~ by volume of friction moclifiers and from 5 up 10% by volume of phenolic resin binder; the carbonaceous component 30-50~ by volume and the inorganic component from 15% to 25% by volume and the organic component from 20~ to 25~ by volume.
D~TAIL~D DESCRIPTION AND PREFERRED EMBODIMENTS
The product of this invention is used in various types of railroad services which are categorized on the ba~is of the contact pressure which is applied across the face of the brake shoe during typical brake application. In service the actual pressures will depend on the type of railroad eguipment on which the brake is used, whether li~ht to emergency brake application is considered, and similar factors. The distinctions, however, are evident and will be clearly understood by those skilled in the art. In addition, AAR
service and heavy duty service commonly employ tread brakes as contrasted to disc brakes.
It is readily apparent from the foregoing that any particular composition selected for AAR use must have good thermal properties as ~ell as undereoing an evaluation of the effect the material will have in use on the metal wheel. These factors and others combine to ma~e the selection of components more of an art than a precise science. Small changes in tha proportion of one component with respect to another can produce considerable differences in the f;nal performance of the brake shoe. For example some combinations of materials ~hile e~hibitin~ ~ood friction chflracteristics in use may prove to be too hard on the metal railroad wheel to be satisfactory for long term use.
With thes~ many considerations and others in mind the composition of the present invention has surprisin~ly been found to exhibit the desired characteristics ~or a molded brake shoe friction material to be a satisfactory substitute for asbestos or other fiber reinforced materials in railroad service.
The first and largest component i~ the present composition 0 i9 an or~anic component which consists of a rubber component bonded together with a phenolic resin. The binder component and rubber matrix are the vehicles in which the other components are embedded.
The or~,anic component may contain mixtures of natural or synthetic rubber, to~ether with e].astomeric materials or a phenolic resin which may be vulcanized or otherwise cured to form a hard matrix for the remaining components. Of the rubbers preferred are the butyl rubbers, styrene-butadiene rubbers or nitrile rubbers. A number of varieties of the various natural or synthetic rubbers and phenolic resins are readily available and are widely described in the litsrature. Numerous rubbers are described in the Vanderbilt Rubber Handbook published by the R. T. Vanderbilt Company in 1968.
Phenolic resins ~enerally applicable for use in the present invention are described in the Modern Plastics Encyclopedia, Vol. 4, No. 10 (1970~1971). Cashew nut shell resins are preferred, primarily due to their excellent bondin~ and heat resistant properties. Such resins and their method or preparation are discussed in U.S. Patent Nos. 2,686,140 and 2,861,964. The or~anic component may in some embodiments be composed entirely of rubber, although most preferably the or~anic component will comprise a mixture of rubbers and phenolic resin~
Tha components listed herein are variously measured as percent by volume rather than the more common percent by weight, except where noted. This i9 done because the volume percenta~e reflects the physical properties of a given shape and size of brake shoe despite variations in the actual chemical composition of the shoe, since in brakin~ service an important factor is the amount of each material which is exposed at the braking surface which is in ~' ~.. ..
contact with the wheel tread. It also simpl;fies the ~escription of the material of the present invention in that it avoids the necessity Eor recalculation of components to account for varying densities of materials selected, such as in the organlc component.
The second component of the composition and one of the key components in any friction composition for brake shoes are the friction modifying a~ents describecl more fully hereinafteI.
A further component of the present composition will be inorganic fillers. These may be fl wide variety o~ granulated inorganic materials which clo not substantially affect the friction properties of the composition, but are rather used to fill out the composi~ion and rectuce the necessity for usin~ more of the expensive organic component. In addition, they also provide thermal properties to some degree, in that they serve as heat sinks.
Typical of the materials which may be used include alumina, barytes, silica, iron oxides, whiting, talc, diatomite9 clays and the like as well as mixtures of these various materials. Particle sizes will normally be in the ran~e of from 4 to 75 microns. The inor~anic fillers will normallg be present as from 5 to 35 percent by volume, preferably 15 to 25 percent by volume of the composition. In the present invention it is important that the inorganic filler component contains neither asbestos fiber nor lead metal or lead compounds.
The third component of the present composition is a carbonaceous component which is composed of carbon particles in any of a variety of forms, such as carbon black, carbon flour, graphite or gound anthracite. A sin~le material such as carbon black or mixtures of the various carbon-containin~ materials may be used.
This component will normally be present in from 30 to 60 volume percent, preferably 30 to 50 volume percent. Normall~ the particle size of the carbonaceous particles will be in the range from .02 to 150 microns. These materials have been and are incorporated in friction materials for several reasons includln~ color, to provide resistance to U.V. degradation of the polymerized materials, reinforcement of the cured rubber component, and the like.
The final materials required in the present invention are "additives" used to volcanize, cure or otherwise modify the rubbers ,~ . . .
~,~ . ..
--5~
and resln~, in the or~anic component. These will naturally vary depend-lng upon the nature of the particular or~anic component used, and the fina] physical properties sought but in general will include mAterials such as sulsphur, zinc oxide, thiazoles, sulfenamides, dithiocarbamates, pero~ides, anti-oxidants, retarders and other processin~ aids. A wide variety of such materials are described in the patent literature ancl the above-mentioned Vanderbilt Rubber Handbook. l'he aclditives ~ill be present as from about 1 to 7 volume percent, preferably 2 to 4 volume percent.
The composition therefore may contain in the cateeories described: cashew nut shell resin and friction modi~iers such as those inorganic materiflls which substantially affect the friction properties of the material. For the purposes of this invention, it will be considered that such friction modifiers are commonly minerals or ceramics havin~ a ~ohs hardness or ~reater than 5.
Typical of such materials are silicon carbide, zircon, garnet, iron chromite and similar materials. The friction modifiers will be in the form of granules having particle sizes in the ran~e from about 0.05 to 200 microns. The friction modifiers will be present as up to 15% volume percent, preferably 5~ to 10% volume percent, of the composition. While the friction modifiers employed herein have been found to have utility in varying amounts in other bra~e shoe compositions includin~ asbestos-reinforced friction compositions and compositions containing steel fibars alone or in combination with metal particles or "grit", the individual use in the amounts disclosed in a brake shoe composition havin~ no reinforcing fiber is somewhat surprising. It will be evident to those skilled in the art from the descriptions of the examples below how best to mix and otherwise formlllate the composikions of the present invention.
Additional descriptions of various types of processin~ equipment including mixers and molds may be found in Stern, ubber: Natural and Synthetic (2d en. 1~67) and Rubber World, ~achinery and ~g~ _nt for Rubber and Plastics (2d edn, 1963) and the patent literature.
The followin~ mo].ded brake compositions is ~ preferred embodiment of this invention, with al:L components listed as percent by weight and by volume:
--6~
Ex~ e I
~ BY WEIGHT ~ BY VOLUNE
Crumb Rubber with 10~ tfllc 12.74 23.36 ~ubbermakers' Sulfur0.51 0.45 TMTD Rubber Accelerator0,25 0.33 MBT Rubber Accelerator0.25 0.31 Antio~idant 0.].3 0.22 Ste~ric Acid 0.13 0.2~
Zinc Oxide 0.64 0.21 Carbon Black Powder 9.17 9.33 Carbon Flour lO.]9 9.33 Iron Chromite 14.0l 5.81 Red Iron Oxide 9.94 3.83 Silicon Cflrbide Nicrogrit 0.64 0.36 Carbon Base Filler 7.39 9.21 Rubbermakers' Hard Clayl8.85 13~39 Hard Rubber Dust 6.37 8.58 ~ineral Rubb0r 3.18 5.61 Liquid Cashew Nut Resin5.lO 9.48 Hexamethylenetetramine0.51 0.91 Total lOO.OO lOO.OO
Certain modifications in the foregoirlg composition can be made without losing the overall advantages of the molded friction material of the present invention. For example the antio~idant can be eliminated altogether as well as the stearic acid where unnecessflry in the molding procesfi. Variations such as these are commonly made in such formulations and can be made in practice without deleteriously affecting the advantages provided by the overall composition.
The important contribution described herein is that a friction co~position as described herein can be satisfactory for AAR
service without the presence of reinforcing fiber of any kind in a brake shoe tread material which pflsses the ob~ective tests and other requirements for AA~ service. The ~mounts of friction modifying agents, additives and processing and other aids can be Adjusted by one skilled ln the art to achieve the desired results.
"~,'~' The invantion ;~ therQîor~ only limit~d by the scope o~ the appended c 1 a im~ .
Claims (7)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A friction material fiber free composition suitable for use as a brake shoe for railroad service comprising by volume:
Phenolic Resin Binder: 1-15%
Carbonacous Component: 30-60%
Organic Component: 15-30%
Inorganic Component: 5-35%
Friction Modifiers: 1-15%
With the balance of other additives being: 1-7%
Phenolic Resin Binder: 1-15%
Carbonacous Component: 30-60%
Organic Component: 15-30%
Inorganic Component: 5-35%
Friction Modifiers: 1-15%
With the balance of other additives being: 1-7%
2. The friction material composition of Claim 1 wherein the phenolic resin component comprises between 5% to 10% by volume of the composition.
3. The friction material composition of Claim 2 wherein the carbonaceous component comprises between 30%-50% by volume of the composition.
4. The friction material composition of Claim 3 wherein the inorganic component comprises between 15% to 25% by volume of the composition.
5. The friction material composition of Claim 4 wherein the friction modifier component comprises between 5% to 10% by volume of the composition.
6. The friction material composition of Claim 5 wherein the organic component comprises between 20% to 25% by volume of the composition.
7. A friction material composition suitable for use as a molded brake shoe for railroad service consisting essentially of:
Crumb Rubber with 10% talc 23.36%
Rubbermakers' Sulfur 0.45%
TMTD Rubber Accelerator 0.33%
MBT Rubber Accelerator 0.31%
Antioxidant 0.22%
Stearic Acid 0.28%
Zinc Oxide 0.21%
Carbon Black Powder 9.33%
Carbon Flour 9.33%
Iron Chromite 5.81%
Red Iron Oxide 3.83%
Silicon Carbide Microgrit 0.36%
Carbon Base Filler 9.21%
Rubbermakers' Hard Clay 13.39%
Hard Rubber Dust 8.58%
Mineral Rubber 5.61%
Liquid Cashew Nut Resin 9.48%
Hexamethylenetetramine 0.91%
Crumb Rubber with 10% talc 23.36%
Rubbermakers' Sulfur 0.45%
TMTD Rubber Accelerator 0.33%
MBT Rubber Accelerator 0.31%
Antioxidant 0.22%
Stearic Acid 0.28%
Zinc Oxide 0.21%
Carbon Black Powder 9.33%
Carbon Flour 9.33%
Iron Chromite 5.81%
Red Iron Oxide 3.83%
Silicon Carbide Microgrit 0.36%
Carbon Base Filler 9.21%
Rubbermakers' Hard Clay 13.39%
Hard Rubber Dust 8.58%
Mineral Rubber 5.61%
Liquid Cashew Nut Resin 9.48%
Hexamethylenetetramine 0.91%
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000410889A CA1190340A (en) | 1982-09-07 | 1982-09-07 | Friction materials for railroad brake shoes |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000410889A CA1190340A (en) | 1982-09-07 | 1982-09-07 | Friction materials for railroad brake shoes |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1190340A true CA1190340A (en) | 1985-07-09 |
Family
ID=4123537
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000410889A Expired CA1190340A (en) | 1982-09-07 | 1982-09-07 | Friction materials for railroad brake shoes |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1190340A (en) |
-
1982
- 1982-09-07 CA CA000410889A patent/CA1190340A/en not_active Expired
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