Sleeve bearing for railway traction motor

An improved sleeve bearing for locomotive traction motor that provides additional lubrication over and above that of the one central wick currently used. The sleeve bearing is provided with a recirculation system comprised of either at least two additional wicks located near the 6:00 operating location or multiple oil communication and delivery grooves passageways communicating with the oil flinger grooves placed for the purpose of collecting and providing a mechanism for providing additional lubrication for extending the oil-wetted envelope available for supporting the truck-axle journal in the axial direction.

BACKGROUND OF THE INVENTION

The present invention is directed to a railway locomotive traction motor and, in particular, to the friction support or sleeve bearing by which the traction motor is partially supported on the axle of the railway truck mounting the underside of the locomotive, and, in particular, the invention is directed to providing additional lubrication.

A conventional railway locomotive pinion-end (PE) traction-motor support bearing, such as that disclosed in U.S. Pat. No. 5,038,631, is shown inFIGS. 1 and 4, whichFIGS. 1 and 4show the half of the support bearing10that contains the window12for passing a lubricating wick. For best overall performance and life of the traction-motor support bearing, the load zones for loading the truck axle-journal should be centered. This is so in order that the lubricating wick (not shown) entering the interior of the bearing via the wick window or opening12lubricates all contacting surface-areas, which lubricating wick contacts the axle-journal through the window. In addition, both load zones should be contained within the total axial dimension of the wick if possible, again in order to ensure the best possible lubrication. Each traction-motor sleeve bearing has two load zones, an upper one and a lower one, and these tend to be heaviest around 25° from vertical because of commonly-used 25° gear-tooth pressure angle. Both load-contact patterns can be seen in the window half10of the PE bearing with the upper load pattern above the lubricator access-window and the lower load pattern below the window. Ideally, both upper and lower load contact-patterns should be centered at mid-length of the window, in order that the wick lubricator provides the best possible lubrication. Further, both load contact-patterns should be contained within the total axial dimension or limits of the wick lubricator if possible, again to ensure the best possible lubrication.

The lubricating wick of the conventional sleeve bearing shown inFIGS. 1 and 4enters the bearing from the lubrication sump through a cast opening in the axle cap, which is aligned with the window or opening12in the bearing liner. This opening12is centered axially on the journal and the wick protrudes through this opening to contact the axle-journal at a position approximately 20°-30° below a horizontal line passing through the axle gear and pinion center lines. The sleeve bearing10also has a flange wick16for lubricating the flange-end20.

The axial length of the preferred journal-to-liner contact area is defined by the axial length of the wick. The bearing liners are machined in such a way as to relieve the liners so that journal contact under normal loads remains in the wick-wetted axial area14. In many traction motor support bearings, however, the envelope available for supporting the journal is significantly longer in the axial direction than the wick and the length of wetted area.

Pinion-end sleeve bearing load ratings are frequently limited by the axial length that can be reliably lubricated by the lubrication delivery system. If lubrication can be assured beyond the axial dispersion of conventional support bearings, that additional length may become useful for supporting the journal. By reducing the unit loading of the original journal and thereby increasing the load capacity, the criticality of other parameters affecting wear rate and reliability are lessened.

In applicants'copending application Ser. No. 11/178,937, filed Jul. 11, 2005, there has been disclosed the use of auxiliary wicks for increasing the wetted area in order to provide additional lubrication to the lateral areas beyond the width of the main central supply wick. These additional wicks are located one on either axial side of the central wick near the 6:00 location and are capable of communicating with the oil accumulated in the oil flinger grooves thereat to thereby take advantage of the oil-flinger rotating lift capability and lateral movement within the bearing lateral clearances for providing additional lubrication and for extending the envelope of the wetted area available for supporting the truck-axle journal in the axial direction. However, it has been found the felt pads constituting these auxiliary wicks may, under certain circumstances adhere to the face of the axle-journal, which may cause part of the auxiliary wick pad to be torn away during the axle-rotation. Moreover, it has been found that the additional lubrication provided by these auxiliary wicks may be better enhanced by more direct fluid communication with the respective flinger grooves which provides the lubricant supply wetting the pad faces of these auxiliary wicks. In addition, it has been found that a more optimal configuration of each auxiliary wick would be helpful in increasing the wick life.

SUMMARY OF THE INVENTION

It is a primary objective of the present invention to provide an improved sleeve bearing for a locomotive traction motor that provides additional lubricated areas in the axle bore over and above that of the conventional central wick currently used.

According to the present invention, the sleeve bearing is provided with the ability to provide additional lubrication to the lateral areas beyond the width of the main supply wick by the addition of additional wicks one on either axial side of the central wick or by incorporating passageways near the 6:00 location on either axial side capable of communicating with the oil accumulated in the oil flinger grooves and taking advantage of the oil-flinger rotating lift capability and lateral movement within the bearing lateral clearances for providing additional lubrication and for extending the envelope of the wetted area available for supporting the truck-axle-journal in the axial direction.

In one modification of the auxiliary wicks, each auxiliary wick is constructed of felt in which the length of the felt fibers constituting the wick pad are oriented in a direction perpendicular to the longitudinal axis of the axle-journal so that only contact of the ends of the felt-fibers are in contact with the journal-surface. In another modification, the auxiliary wick is provided with a projecting tail-portion that projects into the narrow gap connecting the wick-receiving and mounting opening to its respective finger groove, in order to ensure lubrication and saturation of the respective auxiliary wick from its associated finger groove. Also, in order to accommodate any increased compression of the auxiliary wick during contact with the journal-surface, the auxiliary wick is provided with a tapered cross-sectional or concave shape that allows the wick-pad to expand within its wick-receiving and mounting opening, as well as making the auxiliary wick-pad of softer felt in a durometer-hardness range less than that previously used.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawings in greater detail, and toFIGS. 2 and 5for now, there is shown a first embodiment of the railway-locomotive traction motor friction support or sleeve bearing of the invention and indicated generally by reference numeral30. In this first embodiment, the invention is embodied in a friction support bearing that does not employ flinger grooves. Flinger grooves mount flinger rings which, when employed, help to redistribute the oil back to the oil reservoir and reduce oil loss, as disclosed in U.S. Pat. No. 3,905,659. The sleeve bearing30is provided with a conventional central wick window12, as explained herein above with regard toFIGS. 1 and 4, and, in addition, at least two supplemental or auxiliary wicks, one wick32at the outboard end and one wick34at the inboard end. The supplemental wicks32,34are oriented at 6:00 O'clock when viewingFIG. 2. The outboard wick32is combined with the currently-used flange wick16, also explained above with reference to the prior-art bearing ofFIGS. 1 and 4. The wicks32,34are lubricated via lateral flow oil collection grooves36,38, respectively, which are used, as in the conventional manner, for collecting oil, as explained in U.S. Pat. No. 4,229,056. The provision of these additional wicks32,34extend the effective length of the wetted area of the bearing to the areas encompassed by areas A, B and C inFIG. 2, to thus extend the lubricated surface from the hitherto prior-area area A, to thus make significantly longer in the axial direction the available wetted area for contact by the truck-axle journal. To ensure of the additional envelope length available, the simple reliable oil supply system36,38is used. This system collects the lateral oil discharge from the loaded central region serviced by the conventional central wick and delivers the oil to those journal areas beyond the main wick wetted axial area via these additional wicks34,36. Thus, these oil collection grooves36,38also serve the additional function of providing for this additional lubrication of the extended contact areas B and C.

The supplemental wick32is, in the preferred embodiment, narrower than the corresponding flange wick16, although, if necessary, it may be the same or even greater in width. Each supplemental wick32,34has a first overlapping portion32′,34′, respectively, that is received within the interior of a respective channel36,38, and a main longitudinal portion or section32″,34″ extending longitudinally axially in a direction toward the center of the friction bearing. With each overlapping portion32′,34′ positioned in the interior of the respective groove, each groove36,38acts as a sump or reservoir for the additional wicks32,34. Furthermore, the main body portion32″,34″ of each wick32,34is received or mounted in a recess or pocket formed in the interior shell of the friction bearing of similar shape as that of the additional wick32,34, in a manner similar to shown in the embodiment ofFIG. 8as described hereinbelow. Each pocket has a depth less than that of the thickness of the respective additional wick32,34, so that each wick32,34projects or protrudes out from the respective pocket, and interiorly toward the axle-journal mounted in the bearing, for contact against the juxtapositioned surfaces of the journal located within the lateral extent of the above-mentioned contact areas B and C.

Referring nowFIGS. 3 and 6, there is shown a second embodiment of the sleeve bearing of the invention, which is directed to applying the invention to a friction bearing provided with flinger grooves, but without the oil collection grooves36,38of the first embodiment ofFIGS. 2 and 5. The friction support bearing of this embodiment is indicated generally by reference numeral40, and, as shown, utilizes conventional flinger grooves42,44. In this embodiment, the flinger grooves42,44, in addition to serving their conventional function of mounting the flinger rings, as disclosed in U.S. Pat. No. 3,905,659, also serve the function of the lateral-flow oil-collection grooves for the additional wicks52,54. The additional wicks52,54are oriented at 6:00 O'clock when viewingFIG. 3, as in the first embodiment. Since the flinger grooves42,44mount the flinger rings, a separate conventional flange wick56is conventionally mounted. In all other respects, the additional wicks52,54are the same as the wicks32,34of the first embodiment, and are mounted in pockets or recesses similar to those shown inFIG. 8discussed below.

Referring toFIG. 7, there is shown a third embodiment60of the invention in which, instead of using the additional wicks of the first two embodiments to lubricate the additional surface contact areas B and C, oil-flow passageways62,64forming a V-shape are provided on the flange or outboard end, and oil-flow passageways66,68forming a V-shape are provided on the inboard end. These passageways are oriented approximately at 6:00 O'clock when viewingFIG. 7. Unlike the first two embodiments, the friction bearing60is provided with both oil-collection grooves70,72and flinger grooves74,76, in a manner disclosed in U.S. Pat. No. 4,229,056. Each passageway opens into the interior of a respective flinger grooves74,76for fluid communication therewith, and, thus, effectively serve as oil-flow extension grooves of the flinger grooves. The V-shaped passageways62,64, and the V-shaped passageways66,68form an acute angle therebetween, as seen inFIG. 7, and preferably is in the range of between 15 degrees to 45 degrees, although this is not meant to be limiting. This embodiment takes advantage of the proven collection and return system of the conventional inboard and outboard ends of the bearing liner by using the flinger rings to cause oil to flow into the oil recirculation grooves and hence to be delivered to the bearing lateral areas both at the inboard and outboard ends of the bearing liner beyond that wetted by the main delivery wick. While two such passageways have been shown which are V-shaped, more than two such passageways may be employed without a V-shaped configuration.

Referring toFIG. 8, there is show a fourth embodiment80of the invention in which no flinger grooves or oil collection grooves are included in the friction bearing80. In this case, the outboard supplemental wick82is connected to the flange wick84to form one continuous wick. The inboard supplemental wick86is the same as in the first two embodiments. Since the wicks are located at the 6:00 operating position, they would, therefore, receive their lubrication as a result of the natural gravity drainage accumulation from the journal wetted surfaces any time the axle would be at rest. During rotation, the normal supply wick delivers a band of oil on the axle. The supplemental or auxiliary wicks inboard ends would overlap this wetted band and take a portion of this oil to extend the wetted band width.

Referring toFIG. 9, there is shown a fifth embodiment90which incorporates both flinger grooves and oil-collection grooves. The supplemental or auxiliary wicks92are received in pockets or recesses36′ formed in the interior shell of the friction bearing. Each pocket has a depth less than that of the thickness of the respective additional wick, so that each wick projects or protrudes out from the respective pocket, and interiorly toward the axle journal mounted in the bearing, for contact against the juxtapositioned surfaces of the journal located within the lateral extent of the above-mentioned contact areas B and C. Each pocket36′ has an open end96that is in fluid communication with the interior of a respective flinger groove98for lubricating the respective supplemental or auxiliary wick in a manner similar to the embodiment ofFIG. 3. It is also noted that corners36″,38″ of the pockets are rounded to ensure that the wicks are maintained therein.

Use of the supplemental or auxiliary wicks of the present invention allows reduced-width flinger grooves as compared to the prior art friction support bearings, and also allows for the flingers grooves to be moved farther away from the center wick. Also, it is also possible to have a version of the invention where the flinger grooves and the outboard oil-collection groove are eliminated, which would extend the usable load-carrying width approximately one more inch.

In one prototype of the friction support bearing of the invention for use with a General Electric 752 AG traction motor, the width of the crowned load-bearing surface area was increased to approximately 5.18 in. as compared to 3.76 in. for the conventional bearing. Also, each supplemental or auxiliary wick was approximately 1.25 in. in length taken in the direction parallel to the annular flinger groove and 0.81 in. in width taken in the axial bearing direction, with the thickness thereof depending upon proper contact with the axle journal juxtapositioned thereat, and was received in a pocket or recess of width of 0.81 inch and length of 1.25 inches, with the pocket having rounded corners of radius 0.312 in. similar to the rounded corners of the supplemental or auxiliary wick. In addition, the open end96was 0.626 in.

Referring now toFIGS. 10-11C, there is shown a modification of the auxiliary wick92of the embodiment ofFIG. 9. The shape of the auxiliary wick100is similar to that of the auxiliary wick92, except that the auxiliary wick100is provided with a tail-section102which projects from the front in a direction toward the flinger groove98. The tail-section102fits snugly, and may be adhesively secured, in the open end or entrance,104′ of the pocket104. While the outboard auxiliary wick has been shown inFIG. 10, the same holds for the inboard end, as described hereinabove. By providing the tail-section102for each of the outboard and inboard auxiliary wicks, greater lubrication and saturation of the pad will ensue owing to the tail-section102, and therefore the auxiliary wick100proper, being in direct fluid contact with the lubricant flowing in the flinger grooves. Also, the end-walls or end-surfaces100′,100″ of the auxiliary wick100are more curved so that the main body proper of the wick100is approximately oblong or elliptical in shape. This shape helps to retain the wick100in its pocket104. The ends106,108of the pocket104are also appropriately shaped to match those of the wick100, whereby the pocket104is generally oblong or elliptical in shape.

The enhanced oil saturation provided by the tail-section102ensures constant and direct contact with the oil in the slinger groove. This allows oil saturation from the slinger groove to be volumetrically regulated to the felt pad, or wick. In one version, the auxiliary wick100has an overall total length taken between 100′ and 100″ of approximately 1¼ inches, a width (without a tail-section) of approximately ⅝ inch, and a depth of approximately 0.354 inch, with a tail-section102of a length taken in the same direction as the length of the wick100of ⅝ inch and width of ⅛ inch. It is, of course, to be understood that these dimensions may be varied in accordance with various requirements and factors, and are not meant to be limiting.

In yet another modification110of the auxiliary wick, as shown inFIG. 12, the auxiliary wicks ofFIG. 9orFIG. 10may be provided with upwardly-tapering ends112,114in order that there are provided ever-increasing lateral clearances between these ends112,114and the corresponding end walls106,108of the pocket104of the embodiment ofFIG. 10, or of the corresponding end walls of the pocket36′ of the embodiment ofFIG. 9. The provision of upwardly-tapered ends allows for the auxiliary wick to expand within its respective pocket or cavity36′ or104during contact of the wick-face102″ with the surface of the rotating axle-journal and also provide more constant biasing force against the surface of the axle-journal. Depending on various factors and operating conditions, the surface-to-surface contact of the wick-face of the auxiliary wick with the surface of axle-journal causes the felt pad of the auxiliary wick to compress. By providing clearances between the ends of the auxiliary wick and the end walls of the pocket or cavity in which it is mounted, the compression of the wick pad will be accommodated by outward expansion of the auxiliary wick, thereby providing “give” upon the presence of compressions forces during operational contact with the rotating surface of the axle-journal in which the wick. Without such clearances, there is the possibility that excessive surface-to-surface contact and forces would considerably shorten the life of the wick or damage it. Each end112,114of the auxiliary wick110preferably has a taper of approximately five degrees relative to an end wall108or110, but it may vary from being close to zero up to ten degrees. For the embodiment ofFIG. 9, the taper, of course, is zero. For the embodiment ofFIG. 10, five degrees is preferred, though other angles may be used. In addition, each auxiliary wick may be alternatively cross-sectioned such that the end walls are at least partially upwardly and inwardly extending in order to provide clearances between its ends walls and the end walls of the pocket in which it is mounted. For example, a cross-section defining ends112,114that are concave-shaped may also be used, which would also allow for clearances for expansion of the wick. It is also possible under certain circumstances to allow the entire ends112,114to expand within the mounting pocket, in which case the length of the supplemental wick will be less than that of the mounting pocket, as long as adequate adhesive bonding of the bottom surface of the supplemental wick in the mounting pocket is sufficient.

Each additional wick32,92, and100is made of felt material or other comparable composite materials, in order to optimize retention and to provide enhanced capillary effect. The width of each additional wick32,92is preferably less than the width of the flange wick, although such does not preclude the same or greater width. The supplemental wicks are preferably retained by adhesives, or, alternatively, by the geometry of the machined pockets or grooves which also act as reservoirs in combination with the wick geometry. In a preferred embodiment, each auxiliary wick is cut from an SAE F-10 high grade, medium low density felt of 72 inches in width having the following specifications: minimum wool content of 95&, water soluble max. of 2.5%, tensile strength of 225 PSI min. Such felt is sold by, for example, Southeastern Felt and Supply Co. of Concord, N.C., or Aetna Felt Corp. of Allentown, Pa. However, it is to be understood that felt of different grade and specification may be used if it provides the requirements that allow for the auxiliary lubrication of the surface of axle-journal as described hereinabove. The durometer hardness of this felt material is preferably of a specification indicating a softer material in order to reduce felt wick-face pressure against the axle-journal, to thus generate less heat through friction. In addition, this relatively softer felt material, along with the concomitant reduced pad pressure as described hereinabove because of the upwardly-tapering wick, result in increased oil-film thickness and greater oil-retention on the axle journal, which might otherwise be wiped off under operating conditions. It is, of course, to be understood that numerous felt grades or equivalent material may be used meeting the requirements specified herein.

In accordance with the invention, regardless of the particular felt grade used, the felt is not cut in usual manner along which, conventionally, is transverse the direction or length of the felt fibers making up the felt. Instead, in accordance with the invention, the supply of felt is cut along, or parallel, to the length of the fibers constituting the supply felt, as shown inFIG. 13. Referring toFIG. 13, the auxiliary wicks or pads, for example100, are cut from a supply of felt120in a direction such that the fibers of each pad extend in a longitudinally axial direction from the bottom surface102′ toward the upper axle-journal-engaging surface102″. Thus, when an auxiliary wick32,92or100, is in surface contact with the surface of the axle-journal, substantially only the ends of the felt fibers are in contact therewith. Ensuring that only substantially the ends of the felt fiber contact the rotating axle-journal surface is very important in cold climates, under which conditions the face of the felt wick may freeze to the axle. If the felt fibers of the auxiliary wick pads were to run substantially parallel to the axis of rotation of the axle-journal, under freezing conditions, pieces of the actual felt of the wick face or the entire felt could be pulled or torn loose from its position, creating a potential bearing failure. Thus, to remedy this condition, the felt wick is not only adhesively, or otherwise secured, in its pocket or groove, but the longitudinal directional orientation of the felt fibers of the wick extends perpendicular to the wear face of the felt and, thus, also perpendicular to the longitudinal axis of rotation of the axle-journal. With the felt fibers oriented in this manner, if freezing conditions occur, only the portions of the felt fibers would be pulled or torn from the felt wick.

While specific embodiments of the invention have been shown and described, it is to be understood that numerous changes and modifications may be made therein without departing from the scope and spirit of the invention.