Patent Application
20200158227
The present invention relates to mining equipment, and more specifically to improved bearing support systems for crawler drives for mining operations, such as, for example, low seam underground mining.
When a low seam of coal or mineral needs to be mined, the height limits of the seam presents a specific mining challenge. To access low seams, low profile machines, often low seam planetary traction units, are often used to facilitate low seam underground mining operations such as, e.g., high wall mining. Rather than miners using mining tunnels to recover coal, the lower profile crawler with forward cutting heads, or like equipment capable of breaking up the seam, are sent into the seam. These cutting units are typically controlled by a control unit that is behind the unit and outside the seam, and the crawlers are typically propelled running on tracks.
It is known that for facilitating the turning of gears for cutting equipment such as cutting heads and drive train components, bearings, specifically needle bearings, are functionally superior to a bushing and pin system for minimizing friction. The roller action of bearings results in less friction than a bushing and pin system and so superior results. Sufficient lubrication of gears is of serious concern, as the gears might exert a pressure of up to 30,000 foot pounds.
Accordingly, these units would be improved if they could use bearings rather than a bushing and pin arrangements. However, these low-profile machines, because of the nature of the seams they are designed to access, have height limits. The height limits of these units typically rule out the use of normal bearing diameters. Needle bearings are so low profile that they are very difficult to lubricate if placed in these machines. With this type of bearing there is not enough clearance with these machines to successfully let an adequate supply of lubricating oil reach into the bearings, so that due to restricted lubrication oil flow, bearings cannot successfully be used. If the bearings are not adequately lubricated with enough frequency, they will quickly burn out. This will result in the need to remove the bearings for maintenance, stopping the machines from mining. Thus far, this happens often enough to make bearings unworkable.
Bushings, which are less in need of constant lubrication, are settled for instead. Bushings/pin arrangements have instead been used for at least 30 years without improvement.
Turning to prior art
Because of the low profile of needle bearing systems, lubrication reservoirs such as those herein would not lubricate bearings sufficiently, likely resulting in destruction of the bearings.
However, the use of bushings though necessary because of this lubrication issue with bearings, has its issues and is not preferred. The use of bushings results in increased friction and therefore a less efficient rotational motion for the shafts these machines turn, an increased need for maintenance of the bushings and related parts, and an overall reduction in the life of the crawlers.
A bearing type gear system for use with low seam crawler drive for underground mining equipment is shown and illustrated.
The Bearing type gear system is comprised generally of a shaft, a set of multiple lubrication reservoirs (which are concavities or indentations), a needle bearing set or sets, a gear or gears, and gear teeth on the gear(s).
The invention herein has several features that help get lubrication to the bearings to make the bearings compatible with this type of cutting equipment. As lubrication is sent into the shaft and gear area, the reservoirs along the shaft will pick up and hold portions of the lubrication. With a shaft without reservoirs, as is known in the art, the lubrication has nowhere to get purchase and quickly disappears. However, the reservoirs of the design herein, holding lubrication, can then help distribute the lubrication into the bearings over a greater amount of time. Additionally, reservoirs located on each end of the gear also pick up the lubrication and can feed it to the bearings, further into the cavities between the individual bearings. The lubricant in this embodiment can be comprised of any known or acceptable lubricant in the art, such as, as in this embodiment, a lubrication oil. The multiple reservoir design is a special reservoir design which helps to get lubricant to the bearings and does not impede the function of the bearings
Further, apertures through the gear and to the shaft can be provided by pre-drilling between the gear teeth or at other functional points. As lubricant is sent into the gear area, some of the lubricant cam proceed through the apertures and into the shaft area, to the reservoirs, to further lubricate the bearings, in this embodiment, the apertures are located on a protruding bearing wall but can of any number and location wherein they are functionally effective. The bearing wall protrudes above the floor upon which the bearing sets rest and helps secure the bearing sets.
As the gears of a planetary gear system rotate, the shaft is turned directly and turns the gear, or as in this embodiment, the teeth of an opposing gear turn the gear, turning the shaft. The reservoirs are located throughout the surface of the shaft. The reservoirs are distributed, at least in part, in a non-linear manner about the surface. The reservoirs are of a number and location of intervals to provide sufficient lubrication to the entire surface of the shaft of the reservoirs as the shaft turns. The lubricant is forced into the reservoirs and from there, distributed between the bearings to further lubricate the bearing sets
In one embodiment, the lubricant is applied to the outer portion of the gear and via the gear lubrication apertures, is forced onto the surface of the shaft, where the reservoirs help hold and distribute the lubricant to the bearings. This extra lubrication provides additional lubrication to the bearings, which reduces friction and will increase the overall life of the system.
Another feature of the bearing system, which can be present and further improve lubrication, is gear washers with apertures. The gear has gear washers in contact with the gear. The washers each have aperture and in one embodiment, a pair of respective apertures. When lubricant is applied to the gear area, even more of the lubricant is able, by going through the apertures to get into the lubrication reservoirs and thereby the bearing sets, supplying them with more lubrication.
With the ability to use bearings, there is more contact area when torque is applied. This spreads the pressure over more of an operating area than with a bushing and pin type system, reducing wear. This reduction of wear and the need for maintenance, in turn, increases the life of the unit.
With the gear lubrication design disclosed herein, the bearing system can be properly lubricated. Accordingly, with this invention, a bearing type system can be used with the gears herein, and with reduced friction and wear on machinery, and can double or more the life of the friction-reducing assembly.
The detailed description particularly refers to the accompanying figures in which:
Other objects, features and advantages of the invention will become apparent from a consideration of the following detailed description and the accompanying drawings. The following descriptions are made referring to the figures, wherein like reference numbers refer to like features throughout this description. Not all numbers appearing in one figure are necessarily present in another.
For the purposes of promoting and understanding the principals of the invention, reference will now be made to one or more illustrative embodiments. The bearing and support apparatus herein of the present invention may comprise one or more of the following features and combinations thereof as described here. Crawlers are complex pieces of equipment and components such as gears and bearings have been reduced to representative items necessary for understanding of the current invention and do not represent all of the possible components or possible combination of components in the cutting head of a crawler.
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The Bearing type gear system 10 is comprised generally of a representative shaft 12, a set of multiple lubrication reservoirs, which are concavities or indentations, represented herein as 14, 14a, 14b, 14c, 14d, needle bearing sets, represented herein as 16, 16a, a representative gear 18, and gear teeth represented herein as 20, 20a, 20b on the gear 18.
The multi-reservoir shaft 12, the sets of needle bearings 16, 16a, and gear 18 are shown in this figure. The gear 18 component is featured in a partial cutaway view to provide greater visibility of other components. The invention herein has several features that help get lubrication to the bearings 16, 16a to make the bearings compatible with this type of cutting equipment. As lubrication is sent into the shaft and gear area, the reservoirs 14, 14a, 14b, 14c, 14d shown on the shaft will pick up and hold portions of the lubrication. With a smooth shaft without reservoirs, as is known in the art, the lubrication has nowhere to get purchase and quickly disappears. However, the reservoirs 14, 14a, 14b, 14c, 14d of the design herein, holding lubrication, can then help distribute the lubrication into the bearings over a greater amount of time. The reservoirs 14, 14a, 14b, 14c, located on each end of the gear also pick up the lubrication and can feed it to the bearings 16, 16a, further into the cavities, between the individual bearings 22, 22a, 22b. The lubricant in this embodiment can be comprised of any known or acceptable lubricant in the art, such as, as in this embodiment, a lubrication oil. The multiple reservoir design is a special reservoir design which helps to get lubricant to the bearings and does not impede the function of the bearings
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With the ability to use bearings, there is more contact area when torque is applied. This spreads the pressure over more of an operating area than with a bushing and pin type system, reducing wear. Further, this avoids lubrication issues of pin and bushing type systems, which by their very nature, push oil away from pressure points of contact, which naturally creates more wear on both the pin and bushing themselves than happens with the bearing system. In other words, this invention addresses the planetary lubrication problems in low profile crawler systems, allowing for an adequate oil system to planetary gears, making it possible to replace the pin and bushing system with a bearing system.
For truer rotation, the bearing type units operate with less clearance (0.0003 to 0.0006″) than the pin and bushing design (0.009 to 0.012″) and with this system, can now operate with such low clearances. The gear lubrication apertures 28, 28a at the center between the bearing sets 16, 16a help create an oil reservoir to let oil bleed into the bearing sets 16, 16a.
Bearings, on the other hand, because they have much tighter tolerances, have more contact area which causes considerably less friction than the pin and bushing system. The reduces friction, partly by reduction of torque, reduces wear on all components of bearings. This will reduce wear on pressure points and result in less energy needed to operate the crawler unit. The crawler unit will have less down time. This reduction of wear and the need for maintenance, in turn, increases the life of the unit.
The improved design of the shaft 12 for lubrication allows lubrication for the lower profile bearing units, overcoming the previous problem of restricted oil flow, enabling these units to finally successfully use bearings.
The exact sizes and number of reservoirs 14, 14a, 14b, 14c, 14d and apertures 28, 18a that are most suitable may vary with the type of machinery used and conditions, but can be determined by a user, through minimal testing. This is true of the sizes of the bearings 16, 16a as well, including diameter(s) and length(s) of bearings.
With the gear lubrication design disclosed herein, the bearing system can be properly lubricated. Accordingly, with this invention, a bearing type system can be used with the gears herein, and with reduced friction and wear on machinery, and can double or more the life of the friction-reducing assembly. As mentioned, this unit is designed to be used, and enhance the performance and life of, low profile machines, more specifically, machines for low seam underground mining.
While the invention has been illustrated and described in detail in the foregoing drawings and description, the same is to be considered as illustrative and not restrictive in character, it being understood that only illustrative embodiments thereof have been shown and described and that all changes and modifications that come within the spirit and scope of the invention as defined in the claims and summary are desired to be protected.
It is to be understood that while certain forms of the present invention have been illustrated and described herein, the expression of these individual embodiments is for illustrative purposes and should not be seen as a limitation upon the scope of the invention. It is to be further understood that the invention is not to be limited to the specific forms or arrangements of parts described and shown.
