US3022097A

US3022097A - Dust guard

Info

Publication number: US3022097A
Application number: US594127A
Authority: US
Inventors: Seniff Russell Wade; Fracalossi Roland Nicholas; Kangas Pell
Original assignee: Individual
Current assignee: Individual
Priority date: 1956-06-27
Filing date: 1956-06-27
Publication date: 1962-02-20
Anticipated expiration: 1979-02-20

Description

Feb. 20, 1962 R. w. SENIFF EI'AL 3,

DUST GUARD 3 Sheets-Sheet 1 Filed June 27, 1956 FIG].

FIG.

WHEEL WHEEL s og SIDE RUSSELL W. SENIFF ROLAND N. FRACALOSSI 98 I 96 PELL KANSAS ATTORNEYS Feb. 20, 1962 I R. w. SENIFF ET AL DUST GUARD 5 Sheets-Sheet 2 Filed June 27, 1956 WHEEL SEAT ATTORNEYS RUSSELLW'SENIFF ROLAND N. FRACALOSSI PELL KANGAS BY llllllll LATERAL MOVEMENT WHEEL SEAT 15 Feb. 20, 1962 R. w. SENXFF EI'AL DUST GUARD 3 Sheets-Sheet 3 Filed June 27, 1956 FIGJZ.

FIGJI.

INVENTORS SEN! FF RAC A LO 8 S l I RUSSELL ROLAN D N. [5 PEL L K AN G A 3 ATTORNEYS United States Patent 3,022,097 DUST GUARD Russell Wade Seniif, Roland Nicholas Fracalossi, and

Pell Kangas, all of Pratt and Arlington Sts., Baltimore, Md.

Filed June 27, 1956, Ser. No. 594,127 9 Claims. (Cl. 277-433) This invention relates to dust guards for railway axle journal boxes.

Railroad car journal boxes are normally of cast steel with a slot at the rear to accept a dust guard for closing the opening between he box and the axle'which enters the rear of the box. This slot is used in the rough ascast condition.

It is customary practice on railroads to close this opening where the car axle enters the car journal bearing box by using a rigid piece of wood, or material of similar characteristics, which is called :a dust guard. Such a typical dust guard slips loosely into the dust guard slot in the back of the box. It does not fill the slot in any direction, and consequently does not keep oil in the box, or dirt, water, and snow out of it.

Several methods have been previously suggested for sealing the opening at the top of the dust guard slot. Using a wood capping piece on top of the rigid dust guard is one such method of closing this opening. More recently, it has become standard practice to use a strip of fibrous material for filling the slot. Asphaltic material is then applied to the top of the capping piece in the dust guard slot to seal out dirt and water.

Metal covers are also sometimes used to keep foreign material from entering the top opening of the dust guard slot.

Although the top of the slot can be sealed in the several ways outlined above, the dust guard does not seal at any other point in the slot nor does it fit closely to the axle. For instance, a new axle of /2" x journal size has a dust guard seat 6 /8" in diameter. A standard dust guard has an opening of 6 in diameter. This leaves an annular opening between them of through which foreign material can enter and oil can be lost. Dust guard seats on used axles are often badly roughened with nicks caused by striking the box when cars are subjected to impact. It is standard practice to remove these nicks by machining that portion of the axle in order to reclaim it for further use. This further decreases its diameter and increases the annular area between the dust guard and axle.

There are two main conditions responsible for oil loss from the journal box. First, the oil simply overflows the dust guard slot since the dust guard does not seal the sides nor bottom of the slot. Second, the shape and centrifugal action of the axle forces oil out through the annular opening between the axle and dust guard.

This loss of oil is significant for three reasons: 1) the economic value of the oil and labor cost of replacing it, (2) oil lost from the box gets on the rail and causes slippage of heels and loss of traction, which in tum damages rail and equipment, and (3) any loss of oil reduces the margin of safety for effective cooling and lubrication of the journal.

Another disadvantage of the rigid type dust guard is that in conventional journal boxes the axle is free to move, when a car is impacted during switching. etc. until its movement is stopped by contact with the box. This damages the dust guards. In this condition they are rendered practically useless.

Continued impact of the dust guard by the journal at the 4 oclock and 8 oclock positions results usually in serious failure. After being in service for some time,

the dust guard is jammed tightly into the slot along with loose cotton waste packing materials and dirt. Further, the impacted metal area of the inner lip of the slot opening is flattened and turned in such a manner as to lock the dust guard into the slot. This causes extreme distortion of the rigid dust guard and tensile failures consequently occur in the upper half of the rigid dust guard.

A further disadvantage of the loose fitting rigid dust guard occurs when maximum lateral displacement of a worn journal box assembly causes the dust guard to drop oif the dust guard seat and become damaged at its forward edge which contacts the axle on return movement of the box.

Applicants have tested devices offered for effectively closing the journal box at the back side. However, all those tested have some drawbacks. All are complicated and expensive. Most of them are difiicult to apply and remove. The only truly effective prior art seal that was tested which keeps oil in and foreign material out, is quite complicated and creates excessive friction where it contacts the axle. This adds unwanted heat to the journal and bearing, and the torque required to turn the axle appears significant in the aggregate when starting and moving a train.

it is an object of the present invention to devise a. dust guard and oil seal which creates less friction than any now commercially available, and a further object is to prepare a simpler device than those presently available which serves this function.

Another object is to prepare a dust guard which effectively seals the dust guard slot.

A more specific object is to prepare a unitary dust guard which seals the dust guard slot at the top of the box.

An additional object is to prevent oil loss at the junction of a railroad car axle and dust guard, while; at the same time, avoiding the use of complicated mechanisms and also avoiding the generation of excess heat.

A still further object is to devise a dust guard which will move with the railroad car axle in the direction longitudinal with the car, when the car is impacted, without damage to the dust guard.

Yet another object is the preparation of a dust guard which tolerates lateral motion of the axle in relation to the journal box.

An additional object is to devise a dust guard which is sufficiently durable to give several years service.

Another object is to devise a dust guard which will accomplish the other objects set forth and which can be used with conventional journal boxes and lubricating media, as well as with boxes having special lubricating devices.

Other objects of the invention will become apparent from the following detailed description of the invention.

It has now been found that the foregoing objects can be accomplished and the disadvantages of conventional dust guards, as well as more complicated dust guards and oil seals, can be accomplished by employing foamed or sponge polyurethane resins or elastomers to foam a novel dust guard and oil seal, as more specifically set forth subsequently.

Such foamed polyurethanes per se are old and well known. Commonly, they are prepared from a foamable alkyd resin-polyisocyanate material. Generally, 15 to 40 parts of diisocyanate by weight are used with parts of the polyester (alkyd resin) in order to form a flexible foam. A small amount of water with or without acid is used as the foaming agent.

In a specific example, there was employed by weight 100 parts Paraplex U-l48 (polyester resin from a polyhydric alcohol and a dicarboxylic acid, described in Rohm and Haas Bulletin Paraplex U-148 of May 1955, pages 1 to 03 part of Emulfor EL-7l9 (a nonionic emulsifying agent, specifically a polyoxyethylene modified vegetable oil made by Antara Chemical Division of General Aniline and Film Corporation), 2 parts of water and 0.5 part of diethylenethanolamine. To this mixture there was added 30 parts of Hylene TM -(a mixture of 2,4-toluene diisocyanate and 2,6-toluene diisocyanate), When the above composition was employed in a wooden mold, a soft, flexible foam was produced.

In the above formulation, the amount of water can be varied between 1.5 and 2.75 parts. If the dust guard is molded in a wooden mold, it has been found that there are a reducednumber of holes and a better skin is formed by using water in the lower end of the range. To aid in getting a good skin, the mold, whether of wood or metal, can be coated with polytetrafluoroethylene (Teflon).

In place of the specific polyester employed in the above example, there can be employed other polyesters, e.g., the Paraplex U-148 can be replaced by an equal weight of a mixture of 65% of an ethylene glycol-adipic acid polyester (OH value 51, acid value 0.8) and 35% of a propylene glycol-adipic acid polyester (0H value 49, acid value 1.2). Similarly, there can be used a diethylene glycol-adipate polyester having a hydroxyl number 37, acid number 1.6 and average mol. wt. 1900.

The acid number of the polyester is normally below 80 and frequently it has been found preferable that it can be below 50 or even below 10. The OH value of the polyester should be sufficiently high that there are hydroxyl groups available for reaction with the polyiso cyanate. Frequently, an OH value between about 20 and 80 has been found advantageous.

The polyester preferably has terminal hydroxyl groups and hence usually is prepared from components in which the alcohol is in excess. The polyester desirably has a mol. wt. of 1000 or above. There can be employed polyesters prepared from dicarboxylic acids, such as adipic acid, phthalicacid, terephthalic acid, malonic acid, maleic acid, succinic acid, fumaric acid, sebacic acid, glutaric acid, pimelic acid, azelaicacid, and isophthalic acid, and dihydric alcohols, such as ethylene glycol, diethylene glycol, propylene glycol, trimethylene glycol, tetramethylene glycol, 2,3-butylene glycol, triethylene glycol, 1,6- hexane diol, thiodiglycol, etc. Mixtures of acids and/or .glycols can be employed.

As the polyisocyanates there can be employed 2,4- toluene diisocyanate, 2,6-toluene diisocyanate, l-chloro- 2,4 -phenylene diisocyanate, naphthylene-1,5-diisocyanate,

3,3-dichlorodiphenyl-4,4-diisocyanate, hexamethylene diisocyanate, 3,3'-dimethoxy-4,4-biphenylene diisocyanate, diphenylmethane-4,4'-diisocyanate, cyanate, p-phenylene diisocyanate, etc. diisocyanates are preferred.

In some instances part or all of the glycol can be replaced by a polyhydric alcohol such as glycerine or trimethylol propane.

In place of polyesters there can be used polyesteramides, i.e., compounds wherein part of the glycol is replaced by a diamine, such as hexamethylene diamine or The aromatic ethylene diamine,1or by an amino alcohol, such as monoethanolamine or monopropanolamine.

It has also been found extremely desirable in some instances to prepare urethanes wherein, in place of employing a polyester, .there is employed a polyhydric alcohol, notably, the glycols and the polyalkylene glycols. Typical examples of such polyhydric alcohols are ethylene glycol, propylene glycol, tetramethylene glycol, and especially the polyethylene glycols, such as diethylene glycol, triethylene glycol, tetraethylene glycol, hexaethylene glycol, dipropylene glycol, polyethylene glycols of higher molecular weight, e.g., the Carbowaxes having molecular weights of 2400 and 6000, as well as other polyalkylene ether glycols having a molecular weight of at least 750, e.g., polytetramethylene ether glycol molecular m-phenylene diisoweight 2440, as Well as the corresponding compound with molecular weight 2900. When utilizing these polyhydric alcohols there can be employed the same polyisocyanates that are employed with the polyesters; in general, the arylene diisocyanates, e.g., 2,4-tolylene diisocyanate, are preferred. The alcohol-modified urethanes are known as the polyether urethanes or in some instances as the polyalkylene ether glycol diisocyanate elastomers. Illustrative elastomers of this type are mentioned in Schwartz Patent 2,749,960.

The diisocyanated modified polyesters can be foamed by the one shot method described in'the examples above wherein the isocyanate is added last or there can be employed an alternative procedure wherein there are mixed (a) a prepolymer made from a mixture of the polyester, e.g., ethylene glycol-adipate polyester, and the toluene diisocyanate and (b) water, emulsifier and catalyst. When (a) and (b-) are mixed together, the foaming occurs. The prepolymer method of reaction has the advantage that there is less competition between the polymerization reaction and the gas formation reaction, as the toluene diisocyanate is already partly reacted with the polyester to form a polymeric urethane.

The foamed polyurethanes have satisfactory mechanical strength, elasticity, compressibility and resistance to compression set, are oil and water resistant, and are suliiciently heat and light stable to serve as the dust guard. They can be readily fabricated into the desired shapes, either by casting directly into the desired size and shape, or they can be cut into shape from larger sheets thereof.

The invention will be better understood by reference to the drawings wherein:

FIGURE 1 is a longitudinal vertical section through a railway car journal box with the dust guard of the invention shown installed therein with relation to the oar afle;

FIGURE 2 is an exploded view of the dust guard and oil seal of FIGURE 1 together with an applicator plate for inserting the same in the dust guard slot;

FIGURE 3 is a vertical section illustrating the effect of lateral movement of the journal box with an alternative form of the dust guard;

FIGURE 4 is a longitudinal. vertical view partially broken away and in section through a railway car journal box with a modified dust guard having a wire reinforcement and representing a preferred form of the invention;

FIGURE 5 is a front elevation view illustrating the preferred form of the dust guard including the wire reinforcing member;

FIGURE 6 is a vertical sectional view of a further alternative form of dust guard and oil seal;

FIGURE 7 is a fragmentary perspective view of the dust guard of FIGURE 6;

FIGURE 8 is a fragmentary perspective view of a further alternative form of the dust guard showing a solid inner ring;

FIGURE 9 is a fragmentary view with the reinforcing ring omitted and illustrating an especially preferred form of the dust guard having a tough skin on the axle-contacting surface of the dust guard;

FIGURE 10 is a perspective view of another form of the dust guard showing use of an inner ring formed from bristles;

FIGURE '11 is a vertical section of a mold suitable for forming the dust guard of FIGURE 9;

FIGURE 12 is a top plan view of the mold of FIG- URE l1;

FIGURE 13 is a fragmentary vertical section illustrating another form of the invention; and

FIGURE 14 is a fragmentary view of an alternative form of dust guard and also illustrates the application of a tough overall outer coating to the foamed polyurethane as well as the use of a solid lubricant in the inner ring.

Referring more specifically to the drawing, 2 designates a journal box-for a railway car. The car axle '4 has a reduced diameter journal portion 6 extending into the box through an opening 8 of larger diameter than the diameter of the seat portion 7 of the axle. The journal portion 6 joins the main portion 7 of the axle at fillet 10 and is also in contact with 12 below bearing wedge 14. The wheel seat is indicated at 15.

Gpening 8 in the journal box defines an inwardly projecting double rear wall 16. This wall has a vertically extending slot 18 formed in the upper end and a recess or groove 2%) extending vertically down the sides and across the bottom 22 of the box. Slot 18 is open at the upper end thereof. 7 The inside of the bottom of the box is arcuate in cross section and corresponds in shape to the lower end of the dust guard and oil seal 24. The slot 18 and groove are of customary metal construction and form the conventional dust guard slot or well 23 of U-shaped configuration.

The dust guard 24 is plate-like in appearance and is composed of two parts, a relatively thin vertical backing 26 and a main portion 23. Backing 26 is a rigid member designed to facilitate application and removal of the dust guard from the slot. It may be made of metal, e.g., iron, steel, aluminum, etc., or rigid plastic, e.g., phenol-formaldehyde, melamine-formaldehyde, glass fiber-vinyl resin modified polyester laminate, etc. In the specific example shown in FIGURES l and 2, backing 26 is made of thick sheet iron. Its outside dimensions loosely fit the inside of the journal box dust guard slot 23. It is slightly longer than the depth of the slot 23 from the top to the bottom of the box. The opening 30 is larger than the opening 8 in the back of the box, so that the backing 26 will not be moved or damaged on car impact which may cause the axle to move into contact with the box slot ribs. At the top of the backing 26 are extensions 32 forming handles to facilitate application and removal of the dust guard from the dust guard slot.

The main portion 28 of the dust guard is normally of uniform thickness for the major length thereof and made of a foamed polyurethane of the type described earlier, e.g., from Paraplex U-148 or diethylene glycol-adipate polyester reacted with toluene diisocyanate and foamed with the aid of Water. The portion 28 is of the same general shape but is thicker than the inside width of the dust guard slot 23 and must be compressed to enter the slot. After application, it expands to fit and seal the slot at all points.

The portion 28 has an overall length slightly longer than the corresponding inside dimension of the dust guard slot, so that the portion 23 is slightly compressed, but completely fills the groove formed by the slot. The portion 28 is slightly longer than the depth of the dust guard slot, so when applied, the foamed polyurethane extends at 34 above the dust guard slot 23 in the box with the extension in normal, expanded condition being wider than, and sealing, the opening 36 at the top of the dust guard slot against entry of foreign material. The hole 38 in the foamed polyurethane is smaller than the diameter of the opening 8 in the journal box and, in fact, is slightly smaller than the diameter of the main portion or dust guard seat 7 of the axle. This causes it to fit with light pressure both new and used, undersized axles. While the surface 40 of the dust guard which contacts the axle can be flat and of untreated polyurethane foam, it has been found preferable to treat the surface 40 or to provide other contact with the axle as described subsequently.

The dust guard of the present invention, which is of single unit molded design, performs all requisite sealing functions and this has been proven in actual tests. Thus, in contrast to the use of conventional dust guards, there is no oil leakage from the journal box through the bottom groove in the dust guard well and around the dust guard;

Similarly, the oil leakage caused by centrifugal action of the rotating journal observed with conventional dust guards is also eliminated.

The dust guard 24 is formed by casting in a mold as previously set forth. Backing 26 and portion 28 are attached together by making backing 26 a part of the bottom of the mold and casting portion 28 directly upon it by adding Hylene to the mixture of Paraplex U-143 (or the diethylene glycol-adipate polyester) Emulfor EL-7l9, water and diethyl ethanolamine. The foam is formed during the casting due to the reaction of the water with the Hylene and release of carbon dioxide.

No mold release wax (or oil) is used on backing 26, although a mold release wax is used on the rest of the mold. As a result, a tight bond is secured between backing 26 and foamed polyurethane main portion 28 in a very simple manner.

To aid the installation of the dust guard in the dust guard slot, there is furnished an applicator 42 which can be simply a flat sheet of A thick sheet iron. The applicator 42 can also be made of other metal or hard plastic, e.g., phenol-formaldehyde resin. The applicator 42 has a handle 44 to aid in the installation and, in general, has the same outside dimensions as the backing 26. The dust guard and oil seal 24 is applied to the journal box 2 by compressing the foamed polyurethan portion 28 between the adhered metal backing 26 and the applicator 42, pressing the bottom together with the fingers so it will enter the slot 23 in the box. The applicator 42 is then removed by holding down on the handle 32 of the backing while pulling out the applicator, and the compressed polyurethane immediately expands sufliciently to fill the dust guard slot except for the axle receiving opening, as previously described. After insertion of the dust guard into the box, the axle is readily inserted through the seal opening 38 in the dust guard. In actual tests, no oil escaped at any point around the groove 20 in the box even through the oil level was carried up to a point Well above the top of the groove. Nor was it possible to introduce water or foreign material into the box at the top 36 of the slot 18.

The dust guard of the present invention containing foamed polyurethane portion 28 is free to move with the axle without damage to the dust guard when the axle moves within the box in relation to the box opening when a railway car is impacted. In contrast, all conventional dust guards, and most special dust guards and oil seals, are severely damaged in such case, unless some means is provided to prevent the axle from moving in such a manner.

As previously set forth, it is important for best results to provide the foamed polyurethane portion of the dust guard with an impervious skin 46. A thin natural skin can be formed, for example, by casting the polyurethane. foam in a wax coated mold (or in a Teflon coated mold). The skin can be toughened in various ways. Thus, the mold can be lined with a spray coat of Hypalon elastomer (polymeric chlorosulfonated polyethylene) to obtain a good skin. Alternatively, after the dust guard is formed, the foamed polyurethane can be painted or sprayed witha suitable plastic material, such as Hypalon, polychloro-l prene, or an unfoamed isocyanate adhesive, e.g., a di-.'

isocyanate modified alkyd resin, such as glyceryl adipatev polyester reacted with toluene diisocyanate (Hylene), vinyl resins, e.g., vinyl chloride resins including both homo and copolymers such as polyvinyl chloride, vinyl chloridevinylidine chloride copolyrner, vinyl chloride-vinyl acetate copolymer, etc.

The surface 4% of the dust guard which contacts the axle, in addition to preventing oil leakage, must keep friction values as low as possible. Accordingly, a coat-, ing 48 of a friction-reducing agent having good wear char-, acteristics is preferably employed for that purpose. Suitable materials for coating 48 are polytetrafluoroethylene, nylon, e.g., synthetic linear superpolyamides, such as polymeric hexamethylene adipamide, and silicones, such as polydimethylsiloxane, and polymeric mixed methyl- 7 phenyl siloxane resin. Additionally, there can be employed tough polyurethanes, e.g., prepared by curing a liquid polyurethane at 100 to 140 C. to form a polyurethane rubber. This product is especially tough. By incorporating a plasticizer it can be made hard or soft to meet individual requirements. The polyurethaneknown as Adiprcne B, and made by DuPont, can also be used to form the inner ring.

Some slight oil leakage has been noted when the dust guard 24 has a fiat untreated foamed polyurethane inner surface. To overcome this slight oil leakage, other shapes and surfaces have been developed. Thus, as shown in FIGURE 3, the surface can have ridges designed to wipe the oil back into the journal box and to minimize the surface friction between the dust guard and the journal. One side 52 of the ridge is substantially vertical and the other side 54 is slanted downwardly and inward- 'ly into the journal box. From FIGURE 3 it can be seen why the dust guard 24 of the present invention is not damaged by lateral motion of the journal box where the surface 40 (or ridges 50) contacting the journal rides back and forth over the journal fillet 10. It can be seen that the dust guard 24, being held by the pressure of the compressed polyurethane foam in the dust guard slot 23, cannot slip downward in the manner of the conventional rigid dust guard, but instead is suspended over'the journal fillet until subsequent lateral motion returns the dust guard to the normal shoulder position shown in FIGURE 1. In FIGURE 3 there is illustrated a dust guard having a rigid backing 56 having a recessed handle portion 53 united thereto and extending above the top of the foamed polyurethane.

A preferred form of dust guard suitable for use in the present invention is shown in FIGURE 4. In this modification, dust guard 59 comprises a plate-like main portion 60 of foamed polyurethane having axle-receiving opening 62 therein and in place of the

rigid backing member

26 or 56 of FIGURES l and 3, there is a rigidifying element 64 embedded within the foamed polyurethane and extending thereabove to form handles 66. Rigidifying element 64 extends into the interior of plate-like member 60 and around both sides of the central opening 62. Thus, rigidifying element 64 can be in the form of a A diameter iron rod or wire in the form of a U. Preferably, as shown in FIGURE 5, a tie rod 6 of iron is secured across the upper end of the U below the'handles 66. Tie rod 68 completes the reinforcing element. The portion 61 of the foamed polyurethane above the dust guard slot can be of greater thickness than that within the'dust guard well. As shown in FIGURE 4, the foamed portion 60 can be of reduced thickness adjacent the axle-receiving opening to form a sealing ring 70 of foamed polyurethane. No backing plate is necessary with the dust guard of FIGURE 4,

and it is readily inserted into the well with the aid of front and rear applicator plates.

A further modified form of dust guard of the present invention is illustrated in FIGURES 6 and 7 wherein dust guard 72 comprises rigid backing 74 with handle 76 and plate-like foamed polyurethane portion 78. In this modification the foamed polyurethane does not extend up to the axle but, instead, a thin ring 80 of a resilient, wearresistant sheet material is partially embedded in the foamed polyurethane. Ring 80 is preferably made of Teflon or nylon (e.g., polymeric hexamethylene adipamide). This ring serves both as a low friction seal around the journal and as a stiffener that keeps the dust guard in joint movement with the journal during car impacts. As shown in FIGURE 7, the Teflon ring is preferably supplied with perforations '82 to provide a means for mechanically bonding it with the foamed polyurethane. Additionally, the Teflon ring '80 can be coated with an epoxy resin adhesive 84 to further bond it to the foamed polyurethane. A typical epoxy resin is an epichlorhydrinbisphenol A reaction product. In general, the epoxy resins are made from dihydric phenols 0r polyhydric alcohols, e.g., glycerine, and cpichlorhydrin and have an epoxy equivalency between 1 and 2. When the epoxy resin adhesive is employed, it also is possible to omit the perforations in ring 80 due to the powerful adhesive action.

Still another modified dust guard is shown in FIG- URE 8 where attached to the foamed polyurethane portion 86 there is united a wedge-shaped solid urethane elastomer (e.g., ethylene glycol-adipate polyester reacted with Hylene) to form a sealing ring 89 around the journal. The solid urethane elastomer ring insert has excellent wear-resistant properties, recovers rapidly from impact compression because of its flexibility and forms a tight bond with the foam during the molding operation.

A presently preferred type of dust guard is illustrated in FIGURE 9 wherein the foamed polyurethane main body portion 94 has a more dense or solid axle-contacting surface or skin 96 of wear-resistant material. Preferably, the wear-resistant material is a polyurethane and it can be prepared at the same time the foamed portion of the dust guard is formed in a manner to be described below. The wear-resistant surface is normally A to A3 in thickness. The use of the wear-resistant polyurethane surface reduces the friction between the dust guard and the axle. In the form of the invention illustrated in FIG- URE 9 the foam cushions the solid polyurethane material and advantage is thus taken of the compressibility of the foamed polyurethane. The surface 96 of the inner ring has a slope which makes an acute angle with the axle. The other surface 98 of the inner ring is preferably vertical, although it can be at any otherangle which will not interfere with the proper functioning of the dust guard and oil seal.

One of the most critical portions of the dust guard of the present invention is the inner ring which contacts the axle seat and forms the desired seal. It is preferred that the inner ring he made of the same plastic as the marginal main body portion of the dust guard, as is illustrated in FIGURES 8 and 9. However, it is important that the density of the foam be greater in this critical area than in the remainder of the dust guard. Thus, while the density in the main body portion is between 2 lb./ cu. ft. and 10 lb./cu. ft., the density of the inner ring is generally at least double that of the main portion and is up to 60 65 lb./cu. ft.

It has now been found that the inner ring and the main body portion can be made from a single material in a single molding operation by employing the following conditions:

The urethane foam-forming material 100 is poured into 7 mold 102,'shown in FIGURES 11 and 12. The mold has

core pieces

104 and 106 toform the inner ring, and is also shaped to conform with the external configuration of the dust guard illustrated in FIGURES 2 and 10. Through the center of the mold' passes a fixed rod 108 which is threaded in the lower portion thereof to the height of core piece 104. 7 The upper end of the rod is preferably below the top of'the core piece 106. The lower core piece 104, which is fixed to the mold, is /2" high and has flat, horizontal upper and

lower surfaces

110 and 112, and generally has the appearance of a truncated cone with its apex at the top. The acute angle formed by the side of the truncated cone with the horizontal is 45, although this is not especially critical. 'The upper core piece 106 is /2" high, movable, and has flat, horizontal upper and

lower surfaces

114 and 116, and generally has the appearance, of a truncated cone with its apex at the bottom.

Surfaces

110 and 114 are in close engagement so that when core piece 106 is moved, surface 114, in effect, slides on top of surface 110. The acnteangle formed between the side of core piece 106 and surface 110 is 45 although this is not especially critical. The surface 110 is longer in radius than the surface 114.

aoaaoov iug operation. Usually to of molybdenum disulfide, the preferred lubricant, is employed. If too much molybdenum disulfide is employed, the formulation becomes too soft. When other solid lubricants are employed, such as graphite, which is relatively light, there need only be used 3 or 4% of the lubricant by weight of the inner ring composition.

Typical examples of molding a prepolymer type of isocyanate are as follows:

Example 1 in the mold described in FIGURES 11 and 12 and having a wire reinforcement element 64 there was introduced a mixture as follows:

130 grams of a prepolymer known as Isofoam F1 (Isofoam F1 is an isocyanate modified polyester made from 70 parts of the condensation product of adipic acid and ethylene glycol and parts of toluene diisocyanate; the polyester has a molecular Weight of 1817 :22, a calculated hydroxyl number of 72.5 and an acid value of 2.1, manufactured by Isocyanate Products, incorporated), and 5.7 grams of Isofoam Delayed Catalyst (manufactured by Isocyanate Products, Incorporated, and composed of 60 parts of water and parts of tertiary amine). (Other curing agents can be used in place of the Isofoam Delayed Catalyst, e.g., there can be employed 5.7'grams of a mixture of 60 parts water and 40 parts diethylethanolamine as the catalyst in Example 1). This mixture is agitated for about 30 seconds. The mixture during the course of this time began to foam, and Was then poured into the mold in the incipient foamed condition. It continued to rise, and after about 2 minutes, the foam completely filled the mold. The mold was covered, and then placed in an oven and cured at 200 F. for 30 minutes. After curing, the foamed dust guard was removed from the mold and was ready for use, no further curing being necessary.

While in this example the curing time was 30 minutes, the time can be varied between a minimum of 15 minutes of 208 F. and a maximum of 1 hour at 150 R, if desired. At higher temperatures, normally shorter curing times are employed, and at lower temperatures, some what longer curing times are employed.

Example 2 When it is desired to oscillate the foam in order to densify it in the manner previously set forth, then the above procedure is carried out to the point where the mold is completely filled. At this point, oscillation is commenced at a frequency of about 200 times per minute for 15 seconds, with /2" circumferential displacement of the upper movable core mold section fro-m the rest position. Then, the mold was placed in an oven at 290 F. and cured for 30 minutes in the same manner as in the previous example.

In this example the time and temperature of curing can be modified in the same manner as in the previous example.

Example 3 The previous example was repeated. However, in place of oscillation there was employed rotation. The rotation was accomplished by rotating at 60 rpm. for 15 seconds. The rotated mold containing the foam was then placed in an oven and cured exactly as in the immediately preceding example.

The same variations can be employed here as in the two immediately preceding examples.

Unless otherwise stated, all parts and percentages in the present application and claims are by weight.

It will be understood that the above figures and examples are merely illustrative and that a type of rigidify ing element for the foamed polyurethane shown with a specific form of axle-engaging surface, such as a ring, can be used with any of the other axle-engaging surfaces or conversely.

The dust guards of the present invention create less friction than any device now commercially available as an oil seal and dust guard combination. In addition, the novel dust guard is of simple construction and effectively seals the slot, both in the bottom and the top of the box. It also effectively stops oil loss at the junction of the axle and dust guard, while, at the same time, it does not generate excess heat and is economical to operate. Furtheremore, the novel dust guard moves with the ale in the direction longitudinal with the train or car when the car is impacted, without damage to the dust guard, which no other known dust guard will do. Additionally, it is tolerant of the lateral motion of the axle in relation to the box and is sufiiciently durable to give several years service. An additional important feature is that the novel dust guard has practical application to conventional journal boxes and dust wells and lubricating media, as well as to boxes with special lubricating devices.

While polyurethanes are the preferred foamed materials of the present invention, it is possible to employ other foamed or sponge plastics, although with some loss in desirable properties. Among such less preferable foamed materials are polychloroprene, vinyl and viuylidene resins, e.g., polyvinyl chloride, vinyl chloride-vinyl acetatecopolymer, vinyl chloride-vinylidene chloride copolymer, polyvinylidene chloride, vinyl chloride-trichloroethylene copolymer, vinyl chloride-alkyl acrylate and methacrylate copolymers, e.g., vinyl chloride-methyl acrylate, vinyl chloride ethyl acrylate, vinyl chloride-butyl acrylate, vinyl chloride-methyl methaorylate and vinyl chloride-butyl methacrylate coploymers, vinyl chloride-dialkyl maleate, fumurates and chloromaleate copolymers, e.g., vinyl chloride-diethyl maleate, vinyl chloride-dimethyl fumarate and vinyl chloride-diethyl choromalea-te copolymers, polyethylene, polyester resins, e.g., vinylidene monomer modified alkyd resins, more specifically, unsaturated polyester resins from a dihydric alcohol and an alpha, 'beta-ethylenically unsaturated dicarboxylic acid and a vinyl monomer such as styrene modified ethylene glycol-adipate-maleate, ethylene glycol-propylene glycol-adipate-sebacate, silicone resins, such as polymeric dimethyl polysiloxane, methyl phenyl polysiloxane and siloxane resins having the formula where each R is an aliphatic or aromatic hydrocarbon, such as methyl, ethyl, isopropyl, butyl, phenyl, tolyl, benzyl, octadecyl, etc., and n has a value between '1 and 2.' It is frequently desirable'that there be employed a siloxane copolymer wherein there are present both methyl and phenyl radicals with at least 50% of the radicals being methyl groups, nylon, e.g., polymerized epsilon caprolactam, polymeric hexamethylene adipamide and other synthetic linear polyamides, esters of the Dacron and T erylene type, e.g., polymeric ethylene terephthalate, etc. It is to be understood that all of the above just recited resins are in a foamed condition. The resins chosen, of course, should be oil resistant.

The term non-slidable as used in the following claims refers to a dust guard disposed in a dust guardslot, which dust guard does not slide within the slot under the action of an axle passing through such dust guard.

We claim:

1. In combination, a car axle journal box having a dust guard slot therein, and a dust guard in said slot, said dust guard being made of a foamed polyurethane of no mally greater thickness than the interior of said dust guard slot and being compressed to fit into said dust guard slot and substantially filling the entire dust guard slot between the walls thereof.

2. A combination as in claim 1 wherein said foamed polyurethane has a rigidifying element integral therewith.

3. A combination as in claim 1 wherein said foamed polyurethane has an exterior thin impervious skin.

from the mold without disassembling the mold. The core piece 166 has a hole 117 therein, and fitting in the hole is a rod 118 which is connected to any convenient source of power (not shown) to oscillate the same and cause core piece 106 to also oscillate. If desired, the rod 118 can be connected to a source of power which will cause the core piece 186 to rotate rather than oscillate. I The mold 102 has a cover 12% thereon. The cover need only extend far enoughto reach the upper surface of mold piece 106. Peep holes 122 are drilled in the cover 120.

Before the foaming material is poured into the mold 102, wire reinforcing member 64 is placed in position, as shown.

The foam is allowed to form until it just reaches the top cover plate, as seen through peep holes 122. Core piece 166 is then oscillated (or alternatively rotated) about the vertical axis with the aid of power-driven rod 118.

If desired, core mold piece 104 can also be constructed soas to oscillate or rotate rather than remain fixed, although normally there is no need to move that portion of the mold which does not form the wear surface.

a The movement of the circular center mold section appears to shear the foam and causes the cell structure to collapse and re-form during its foaming period, thus densifying the foam in this area, as at 128. The shearing action extends to distances up to A" or even more from the surfaceof the rotating or oscillating mold section. Preferably, the densification is carried out to a distance of at least A The desired density can be achieved by controlling the extent and speed of rotation or oscillation, and by controlling the gelling of the foam.

Generally, a rotation between 2 and 100 rpm. for 10 seconds to 120 seconds is employed, or oscillation corresponding to a frequency of 50 to 1500 times per minute for to 120 seconds is employed.

The presently preferred type of movement is oscillation at a frequency of 200 times per minute for about 15 seconds, with a /2 circumferential displacement of the core mold section from the rest position.

The minimum amount of displacement is a function of the cell size in the foam, and generally is the diameter of the cells of the foam.

:The' utilization of the two piece core mold construction of the type illustrated in FIGURES l1 and 12 has the additional further advantage that the air pocket which would otherwise tend to form at 126 is eliminated. This is important in that it is at precisely this point that the dust guard and oil seal contacts the axle.

Still another kind of contact surface for the dust guard is showu in FIGURE wherein nylon bristles 90 are cemented into the foamed polyurethane portion 92 of the dust guard. As the cementing agent, there can be employed' an adhesive, such as the epoxy resins previously set forth. The nylon bristles bear on the axle. The pressure of the bristles against the axle is very light and wipes the oil forced up the fillet of the axle by the centrifugal action when the axle is rotated back into the box. In place of nylon bristles, there can be employed Teflon form a unit /2" x 1 x 1 /2 inch and then wrapping a piece of screen around it to hold it intact. In place of iron screening, there can be used screens of other metals and noncorrosive metal pads such as Brillo, neoprene coated pig hair or Wool hair, or even iron wire screening, coarse polyurethane foam, etc. In general, any open, coarse, porous structure can be employed.

The reason that this breather 130 is frequently advantageous is in part due to the fact thatthe reciprocating motion of the axle 4 in the journal box 2 causes a considerable displacement of air. It is possible with a worn journal box and axle assembly to be within the prescribed AAR regulations and to have a total movement of two inches which displaces 30 cubic inches of air in the journal box with each inward full stroke of the axle. A similar amount of air is drawn in with each full two inch withdrawal of the axle from the journal box.

When the journal box lid is air-tight and a dust guard and oil seal is used in the journal box slot, the pumping action of the axle in the journal box just described causes considerable flexing of the dust guard. Such flexing causes additional movement of the dust guard in the direction parallel to the axle. The breather 130 reduces the resulting pressure on the dust guard.

Tightly sealed boxes also have the disadvantage that water vapor formed by condensation and evaporation inside the journal box normally has no means to escape. The use of the breather 130 overcomes this problem.

The compressible breather, as shown in FIGURE 13, is located in the upper section of the dust guard 132 above the axle receiving opening and just below the upper end of the opening in the journal box slot 136. This location is protected by the overhang formed by the outer wall of the slot. The breather is sloped downwardly to the outside of the box.

It is emphasized that the breather is not primarily a filter. The latter would require maintenance of a type not economically feasible. The breather 139 will not clog up with air-borne dust as would a filter.

To prevent impregnation of the wire screen breather device during formation of the dust guard, it is completely wrapped with a thin, absorbent paper tissue. The breather is then placed in the proper position in the mold and. foam is formed around it. When the formed dust guard is removed from the mold, the exposed paper covering on the breather is removed.

In place of the wire screen breather, the breather can be formed by forming small holes in the polyurethane foam in the molding process. These holes are located at the same position as described above for the breather block 139. The holes likewise are sloped downwardly to the outside. Generally, the holes are small, e.g., about to 4; in diameter and are supplied in suflicient number to provide about A" cross-sectional area of bristles which also have low friction characteristics and in about 16 meshes per inch. The breather can be made.

by taking a piece of wire screen about 30 inches long and 1 inches wide, pleating it in /2 inch intervals to opening.

With conventional lubricator pads, packs or waste rolls, oil is provided by wicking action to the journal. The entry of air-borne dirt ranging in size up to 89 microns into the journal box, as is possible with the breather 130, however, is not necessarily deleterious because the dirt cannot travel with the oil through the lubricator media. That portion of the dirt that impinges directly on the rotating surface is relatively small.

Oil cannot escape from the box through breather because it is positioned above the only possible lines of flow for the oil.

FIGURES l3 and 14 also illustrate another aspect of the present invention, namely, employing a solid lubricant 138 in the inner sealing ring 140 which surrounds the axle. In the specific'example illustrated by FIG- URES 13 and 14; the lubricant is molybdenum disulfide in an amount of 19% by weight of the polyurethane composition used for the sealing ring. The molybdenum disulfide is dispersed throughout the urethane forming material employed to make the inner ring prior to the mold- 4. A combination as set forth in claim 1 wherein the axle engaging surface of said dust guard has a coating of a friction reducing plastic.

5. In combination with a railway car axle journal box having an axle-receiving opening and vertical walls forming a dust guard well surrounding said opening, a dust guard comprising a vertical rigid backing wall and a foamed polyurethane adhered to said backing wall, said polyurethane having an axle-receiving opening therein and said rigid backing wall having a substantially larger central opening therein than the opening in said polyurethane, said polyurethane being compressed to fit within said dust guard well and extending therebeyond to form an oil seal.

6. In combination with a railway car axle journal box having an axle-receiving opening and vertical walls forming a dust guard well surrounding said opening, a dust guard comprising a foamed polyurethane having an axlereceiving opening therein and a rigidifying element embedded within said polyurethane and extending above the upper side of said polyurethane, said polyurethane being compressed to fit fixedly within said dust guard well and extending thereabove to form an oil seal.

7. In combination with a railway car axle journal box having an axle-receiving opening and vertical walls forming a dust guard well open at its upper end surrounding said opening, a dust guard of unitary sheet construction within said well and extending above the open upper end therof, said dust guard comprising a foamed polymer of normally greater thickness than said well and which is compressed to fit fixedly within said well, said dust guard substantially filling said dust guard well between the walls thereof, the portion of the dust guard above said well being relatively uncompressed whereby it forms an oil seal for said journal box.

8. In combination with a railway car axle journal box having an axle-receiving opening, an axle journalled in said opening and a pair of vertical walls forming a dust guard well open at its upper end surrounding said opening, a dust guard of unitary sheet construction within said well, said dust guard comprising a foamed polyurethane marginal main body portion of normally greater thickness than said well and which is compressed to fit fixedly within said well and a thin inner sealing ring of resilient,

wear-resistant, plastic material united to said foamed polyurethane and contacting said axle.

9. In combination with a journal box having aligned axle-receiving openings in a pair of spaced vertical walls and forming a dust guard slot opening at its upper end, a seal within said slot comprising: a body formed of a single sheet of elastic and compressible material in the nature of sponge rubber having an axle receiving opening of less diameter than said wall openings, and a contour conforming to that of said slot, said body normally having a thickness throughout greater than the width of said s-lot, also a length greater than the depth of said slot, the portion of the body disposed between the axle-receiving openings therein and the edges of said walls defining said openings, being uncompressed so as to have a thickness throughout greater than the Width of the slot, said greater length of said body providing an uncompressed marginal portion which extends out of said slot to form a seal at the mouth of said slot.

References Cited in the file of this patent UNITED STATES PATENTS 708,491 Patten Sept. 2, 1902 2,117,392 Banigan May 17, 1938 2,151,410 Richter Mar. 21, 1939 2,152,937 Vigne et al Apr. 4, 1939 2,401,539 Benson June 4, 1946 2,590,156 Carpentier Mar. 25, 1952 2,647,774 Newberry Aug. 4, 1953 2,682,685 Mathues July 6, 1954 2,709,095 Miller May 24, 1955 2,717,024 Jelinek Sept. 6, 1955 2,731,669 Talalay Ian. 24, 1956 2,746,778 Hurlburt et a1 May 22, 1956 2,760,953 Seeger Aug. 28, 1956 2,781,208 Foss Feb. 12, 1957 2,793,885 Hoyer May 28, 1957 2,798,746 Hoyer July 9, 1957 OTHER REFERENCES Publication, Engineering Potential of Polyethylen, 288-SR (Lee), Product Engineering, July 1952.

Gaskets (Elonka), published in March 1954 edition of Power, page 113 relied upon.