US 2151410 A
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Description (OCR text may contain errors)
March 21, 1939. i H. w. RICHTER 2,151,410
ART OF MAKING DUST GUARDS AND/OR PACKING Filed Oct. 17, 1935 ill/4 Patented Mar. 21, 1939 ART OF MARIN? DUST GUARDS AND/OB ACKING Herman W. Richter, Bridgewater,'Mass., assignor to George 0. Jenkins Company, Bridgewater, Mass, acorporation of Massachusetts Application October 17, 1935, Serial No. 45,419 6Claims. (01.286-6) This invention relates to dust guards and packing devices, particularly to those of the general type used in the journal boxes of railroad rolling stock for the purpose of retaining the oil and excluding dirt, dust, and water from the bearing surfaces.
The dust guard commonly in use up to very recent times was in most cases nothing more than a piece of material usually shaped like a capital letter U closed at the top and provided with a.
circular hole to allow the axle to pass through it. The journal box is commonly provided with a slot or compartment which accommodates the guard, and the guard is made of such dimensions 1 as will permit its free movement in the slot, that it may follow the movement of the axle without being subjected to stresses which may break it.
The simple form of guard, used almost ex- 'clusively up to very recent times and still largely in use, is usually made of wood or fabricated fibrous material, leatherboardbeing one of the fabricated fibrous materials most in favor.
While these simple guards have apparently rendered reasonably satisfactory performance under most conditions, it has become understood in late years that they are by no means perfect dust and water seals and have failed to accomplish the purpose for which they are used. Axles vary considerably in diameter since they are turned down, when worn, to gauges considerably less than those which are standard for new axles. Dust guards must necessarily be made in a limited number of sizes, and it is frequently found that an axle has been so far reduced in 35 diameter as to leave a considerable clearance between the axle and the dust guard. This permits dust, grit, and moisture to work into the bearing, the dust guard falling, under these circurnstances, to perform its function.
40 A- further factor which contributes to the failure of the conventional dust guard to protect the bearing is the fact that it is not held with a fair degree of rigidity against the face of the dust guard slot adjacent to the car wheel; and the 45 very .freedom of motion that insures the guard against breakage permits dirt and water to work underneath and around it into the bearings. Furthermore the side of the slot against which the dust guard could be made to press by means 50 of springs-and sometimes is-is a rough, un-
finished casting, and since guards are usually made of relatively hard, inflexible material it is not possible to secure a good degree of adaptation to the side of the slot even when spring pressure 55 is used.
Of recent years these failings have been recognized and several attempts have beenmade to produce a guard which will-not only (a) hug the axle at all times but (b) will prevent the ingress of foreign materials around the guard. Since, 5 however, most of these new guards depend on the flexibility of a rubber or leather sleeve for the achievement of result a, installation presents certain problems. It is usually necessary to provide some sort of stretching or distending appalo ratus which opens the dust guard hole and holds it in that position while the journal box is being slipped over the axle. Installation thus becomes a time-consuming and somewhat difficult process.
The present invention, reduced to its simplest 1 terms, makes use of the expansion of a com pressed sponge of rubber-like material to do two things:
(a) To provide perfect adaptation to the axle. 20 (b) To provide perfect yet flexible adaptation of the guard to the face of the dust guard slot adjacent to the car wheel.
One construction embodying the principle described and designed to meet condition (a)-i. e perfect adaptation to the axleis shown in the accompanying drawing in which Figure 1 is a central vertical section through an axle box of conventional construction, showing an axle and the dust guard of this invention in position therein.
Figure 2 shows in perspective a piece of material from which one portion of the guard is made.
Figure 3 shows in perspective a strip of the same material.
Figure 4 is similar to Figure 2, but shows the strip in compressed condition ready to be inserted in the guard.
Figure 5 is a perspective view showing the strip of Figure 4 bent into ring form.
Figure 6 is an elevation of the dust guard ready for application of the element of Figure 5 thereto.
Figure 7 is a section on line 1-1 of Figure 6.
Figure 8 is a view similar to Figure '7 but showing the ring of Figure 5 in position.
Figures 9 and 10 are fragmentary sections to a larger scale showing the guard as first placed in position in the box and after conformation to the axle and box, respectively.
The guard is made in the usual shape but is composed of three laminated pieces. The two outside ones It are thin, die-cut pieces of a very strong, rigid, oiland water-proof material, preferably of the type represented by the lamistru'ction. The axle hole l2 in the outside pieces is made large enough so that the guard will slip easily over the largest axle A that may be encountered in service, but the hole in the filler piece II is considerably greater in diameter-at least or so. When the three pieces are assembled the greater diameter of the filler piece provides an annular depression l3 in which a strip of expansible material maybe inserted.
The three pieces l and I l are secured together by means of casein glue, it having been found that this adhesive gives a bond, when used with the aforesaid materials, that is remarkably resistant to water and to oil, hot or cold. Rivets or wire-stitching may be employed, if necessary,
' to enhance the rigidity of the assembly.
Into the annular space l3 produced as described above is placed a strip of elastically expansible material, hereafter referred to as sponge rubber. Ordinary rubber, not being oil-resistant, is unsuited for my purpose, but I find that the synthetic rubber-like product known as Duprene is entirely satisfactory. This material maybe compounded, in substantially the same manner as ordinary rubber, to produce a porous, oiland heat-resistant sponge. I produce this sponge M in a thickness substantially equal to the difference in diameter between the outside and filler pieces, so that when strips l5 are cut from it and inserted into the annular depression Hi the sponge will protrude into the center hole to a distance about equal to the depth of the depression.
In practice, the sponge rubber strips are soaked in hot wax until they have become thoroughly saturated with the wax and sink in it. They are box 20 to be slipped over the axle with ease. At
the outset it is no more efficient than an ordinary guard, but within a very few minutes after the car is set in motion the axle temperature rises to a point at which the wax becomes sufiicently plastic to permit expansion of the sponge, and adaptation to the axle becomes positive and complete. Because of the fact that the sponge remains under compression, adaptation continues perfectly until wear has materially reduced the thickness of the sponge rubber insert.
I have found it advisable to produce my sponge strips with a wear-resisting, anti-friction surface made by incorporating a lubricant in a nonspongy rubber l'lcompound facing. Graphite is one example of a lubricant suitable for such use.
A construction embodying the principle described and designed to meet condition (Ll-i. e.,
perfect yet flexible adaptation of the guard to the face of the dust guard slot adjacent to the car wheel, is the following? A sponge rubber compound is made in such a thickness as when added to the thickness of the body of the dust guard will produce a total thickness considerably greater than the width of the dust guard slot. The average dust guard slot has a width of 5 The average dust guard has a thickness of A sponge rubber compound .would therefore be made in a thickness, in the uncompressed stage as in Figure 2, of at least it being preferable, however, to make it enough thicker so that when heat permits the compressed sponge to expand the sponge will exert considerable pressure against the face 2| of the dust guard slot 22 adjacent to the car wheel.
This sponge rubber compound is either 'cut to the shape of the dust guard or is preferably, to prevent waste of material, moulded directly to this shape in the curing operation. It is attached as at 18 to the dust guard by a suitable adhesive, with or without stitching and/or riveting. Prior to attachment it is desirable to remove the skin on the faces and edges of the sponge, or at least on the edges, to permit rapid saturation with the compound used to maintain the sponge in the compressed condition. The guard, with attachedspongy facing, is nowimmersed in the impregnating material; and when the sponge is thoroughly saturated the assembly is removed and subjected to pressure, whereby the sponge is compressed to a fraction of its normal thickness. When the assembly has cooled, the pressure is released and since the thickness of the guard with its compressed sponge facing is now considerably less than the width of the dust guard slot it may readily be dropped into position in the slot. Such a construction does not at the outset accomplish its purpose; but as soon as heat is generated in the journal box the sponge expands, providing perfect adaptation to the face of the dust guard slot adjacent to the car wheel. Since the thickness of the expanded sponge is considerable, the guard is permitted, due to the flexibility of the sponge rubber, a considerable freedom of movement in all directions without material reduction in the completeness of its adaptation to the slot facing. It is, of course, obvious that instead of applying a single thick sponge facing to one face 'of the guard, thinner sponge facings may be applied to both faces. It is also obvious that, without departing from the scope of this invention, the sponge facing may be in the form of a wide ring surrounding the axle hole and that still other shapes may be designed for the purpose of decreasing the amount of sponge compound required. It is further obvious that springs 25 may be used on the face of the dust guard opposite to the one which bears the sponge facing, such springs serving to press the guard firmly yet yieldingly against the side of the slot adjacent to the car wheel. An advantage of this construction is found in the fact that a guard so made is much more easily removed from the slot when'the bearing is dismantled.
The foregoing constitutes the essential and distinctive thought of my new invention, but it is to be understood that while I have gone into considerable detail and utilized certain specific terms and language, the present disclosure is illustrative rather than restrictive, and that changes and modifications may be resorted to without departing from the spirit and scope of my invention. Furthermore it is to be distinctly understood that the essence of my invention may be combined with various other steps and details without affecting the peculiar results obtained.
I claim: I
1. The method which comprises securing to a face of a member a layer of spongy elastically expansible material, saturating said material with a molten thermoplastic, compressing said material against said member while the thermoplastic is molten and causing the thermoplastic to harden while said material is compressed to thereby retain said material in its compressed state, and then removing the compressing pressure.
2. The method which comprises securing to a face of an axle dust guard member, a layer of spongy elastically expansible material to a thickness such that the combined thickness of the dust guard including said member and material is greater than the width of the axle box slot into which said guard is to be placed, saturating said layer with molten thermoplastic and compressing said layer and member to a combined thickness less than said width and causing said thermoplastic to harden during the continuance of such pressure to thereby retain said dust guard in compressed state, whereby after said dust guard has been placed in said slot the subsequent heating of said guard by the heat generated by rotation of said axle in said box will soften said thermoplastic and permit expansion of said material to tighten said dust guard in said slot.
3. An article of manufacture consisting of a dust guard for axle boxes, which comprises sheet material having a hole for receiving said axle, said hole being of greater internal diameter between than adjacent to the side faces of said sheet to form an annular channel, and packing material within said channel comprising elastically expansible spongy material held in compressed state by a solidified thermoplastic saturant and presenting an opening to receive said axle larger than said axle and having a close textured surface containing a lubricant in confronting relation to said axle.
4. An article of manufacture consisting of a dust guard for an axle box, said guard comprising a plate having a hole for receiving an axle, said plate having a facing for the interior of said hole and on at least one side face of spongy elastically expansible material held in compressed state by a hardened thermoplastic saturant and adapted to be released into sealing engagement with said axle and adjacent portions of said box on subsequent softening of said saturant.
5. An article of manufacture consisting of a dust guard for an axle box, said guard comprising a plate having a hole for receiving an axle, said plate having a facing for the interior of said hole and on at least one side face of spongy elastically expansible material held in compressed state by a hardened thermoplastic saturant and adapted to be released into sealing engagement with said axle and adjacent portions of said box on subsequent softening of said saturant, said material when inreleased cone dition being flexible and permitting relative motion between said axle and box while maintaining sealing contact therewith.
6. An article of manufacture consisting of a dust guard for axle boxes, which guard comprises a plate of rigid material having a hole for receiving an axle and having a facing of a spongy elastically expansible material retained in compressed state by a hardened thermoplastic saturant, the aggregate thickness of said plate and said facing in compressed state being less than the width of the slot in the axle box to receive it and in uncompressed state greater than the width of said slot.
HERMAN W. RICHTER.