Railroad Car Axle Bearing Overheat Indicator

Abstract

The roller bearing cover mounted on each end of a railroad car axle is provided with a projecting grease fitting. Tightly gripping the outer end of this fitting is the socket of a cap that covers at least part of the bearing cover. At least a portion of the outer surface of the cap is a predetermined color that will change to another color if the cap is heated to a predetermined temperature by overheating of the bearing and axle.

Description

Hot boxes have always been a problem with railroad cars. If they are not discovered in time, they can cause train wrecks. The usual practice has been to check the journal boxes at certain points along the right-of-way while the train is standing still, but of course this does not take care of dangerous conditions that can develop between stops. In an effort to solve this problem, electronic means have been provided for detecting hot boxes while the train is in motion. The trouble with such a system, which is expensive, is that for various reasons false indications are given and the train often is stopped needlessly because actually there is no hot box.

The most modern freight cars do not use babbitt brass bearings in journal boxes, but use sealed roller bearings with which journal boxes are not necessary. Nevertheless, there are times when the bearings overheat and create the same problems encountered with hot boxes.

It is among the objects of this invention to provide means for indicating visually when a railroad car roller bearing is overheating, which is simple and inexpensive, which is reliable, which does not give a false indication of overheating and which will indicate a hot bearing while the car is in motion or standing still.

The preferred embodiment of the invention is illustrated in the accompanying drawings, in which

FIG. 1 is a fragmentary side view of one end of a railroad freight car truck;

FIG. 2 is an enlarged end view of the bearing cap, but showing the heat indicator in place;

FIG. 3 is a cross section taken on the line III-III of FIG. 2;

FIG. 4 is a view of the heat indicator after a color change; and

FIG. 5 is a section through a modification.

Referring to FIG. 1 of the drawings, a roller bearing is mounted on the end of a railroad car axle and is held in the side frame of the truck 1. The end face of the axle customarily is provided with three equally spaced threaded bores around its center which receive capscrews 2. These screws are used for holding the bearing cover 3 in place against the axle. As shown in FIG. 3, the center of the cover is provided with a threaded passage 4, in which a grease fitting 5 of the Alemite type is screwed. The inner end of the fitting is in communication with the inside of the bearing so that grease can be injected through the fitting into the bearing.

In accordance with this invention, a cap is mounted on the grease fitting. As shown in FIGS. 2 and 3, this cap has a flat body 7, from the back of which a socket 8 extends. The socket is adapted to fit tightly onto the grease fitting to hold the cap in place. For this purpose, the socket preferably is provided inside with an annular groove for receiving the flange 9 at the outer end of the grease fitting. To enable the socket to be pushed over the fitting so that the flange can snap into the groove, the socket may be made of slightly resilient material such as a synthetic plastic that will have enough spring to it to allow the socket to be pushed into place. If the socket is metal, it can be divided into arcuate sections 10 as shown in FIG. 5, which can be sprung apart far enough to allow the socket to be pressed over the fitting. The body of the cap is designed to be held tightly against the heads of the capscrews, so that they, as well as the grease fitting, can conduct heat from the axle and bearing cover to the cap. Also, for best results, the cap has a peripheral flange 11 or sidewall extending around it and the capscrews and nearly engaging the bearing cover to form inside the cap a closed area that can become heated.

The outer surface of the cap is a certain color which has been decided upon. By "outer surface" is meant the surface itself, or what appears to be a colored surface, such as when the color is behind a transparent surface. The entire outer surface of the cap can be this color, or only a given area of it. If the cap is made of a plastic, the color may be in the plastic itself. If made of metal, as shown in FIG. 5, the color is coating 14 applied to the cap. In either case, at least part of the colored area is formed of a material that will change to another color, either lighter or darker and including readily recognizable changes in tint, when the cap is heated to a certain temperature. If the color-changing material is limited to one or more areas of the body of the cap, the color change will contrast with the adjoining area, as indicated in FIG. 4, which has been hatched for color. If it is determined that the temperature of the axle should not exceed 300.degree. F., for example, during overheating, then the color should be one that will change when the cap becomes heated by the axle reaching that temperature. Since the cap will never become as hot as the axle, in this particular example the color must be one that will change at some elevated temperature below 300.degree. F.

There are many coloring materials that can be used for the purpose of this invention. For example, a composition including 30 parts of cuprous iodide and about 70 parts of mercuric iodide will change from bright red to a brown at about 65.degree. C. A mixture of lithographic varnish, "bronze orange," titanium dioxide and a drier can be made that will change from orange to red at about 90.degree. C. A large number of pigments that change color at various temperatures are listed in U.S. Pat. No. 2,928,791.

When any railroad man watching a freight train pass sees that one of the caps just described has a different color than the other caps, or has become two different colors, he will realize that the axle and bearing associated with that cap are overheating and that the train should be stopped so that the hot bearing can be attended to. The color change should be irreversible so that if the train stands long enough for the hot bearing to cool before the color change is noticed, the color will not revert to its original color, but can still be seen. Therefore, once a cap has changed color it must be removed and a new one put in its place.

A cap such as described herein is very inexpensive and simple to mount in place. It will not give false alarms. Its change of color when there is an overheated bearing can easily be seen. The cap also has the additional feature of keeping the outer end of the grease fitting clean between grease jobs.

Claims

I claim:

1. The combination with the flanged grease fitting projecting from the center of the roller bearing cover fastened to an end of a railroad car axle by capscrews, of a cap overlying the outer ends of the capscrews and provided with a central socket receiving said fitting and tightly engaging it to hold the cap against said cap screws, at least a portion of the outer surface of the cap having a predetermined color that will change to another color if the cap is heated to a predetermined temperature by the axle.

2. The combination recited in claim 1, in which said cap is formed of a synthetic plastic having said color-changing characteristic.

3. The combination recited in claim 1, in which said outer surface of the cap is formed from a coating of material having said color-changing characteristic.

4. The combination recited in claim 1, in which only part of said outer surface has said changeable color.

5. The combination recited in claim 1, in which said cap has a flat body engaging the outer ends of said cap screws, and an integral flange extending inwardly around said screws substantially to said bearing cover.