Patent Application
20110181095
This disclosure relates to rack bar haulage systems and the means by which the rack bars are secured and retained to armor face conveyors, in particular, though not necessarily exclusively, for underground longwall mining.
Longwall conveyors normally operate with a powered coal-cutting machine, a shearer that is mounted onto the face conveyor. The shearer hauls itself along the face conveyor in both directions by means of a haulage system. A rack bar haulage systems comprise a series of rack bars pinned to support brackets, called clogs, welded to the individual armor face conveyor elements, the line pan. The shearer engages with the racks via a shoe that permits free movement in the direction of shearer travel only. The shoe also houses a drive sprocket that engages the rack teeth to provide the required haulage load to cut the mined material. The shearer drive gear wheel meshes with uniformly spaced horizontal teeth extending between two spaced apart cheek plates to form the rack bar.
All rack systems must withstand shearer haulage forces in various directions and their retention methods must cope with the tendency of the shearer shoe to bulldoze material in front of it as it passes along the conveyor.
In conventional longwall mining, as illustrated in
As illustrated in
The movable and immovable rack bars 7a and 7b, respectively, of the rack device 7 are provided at both ends of each segment with a nose-shaped extension 12 which projects downwardly. This extension includes a bore for accommodating a connecting bolt 11 forming a pivot shaft. As shown in
Each of the clogs 10 is provided with a slot 13 located on one-half of the holders that is nearest the joint between the conveyor pan sections. The slots 13 in the clogs 10 extend in a direction corresponding to the longitudinal orientation of the face conveyor. The connecting pins 11 extend through the slots and provide the associated movable rack bar 7a with adequate mobility with respect to the face conveyor. The immovable rack bars 7b are fixed with respect to the face conveyor 2 by the connecting bolts 11 which retain these rack bars by extending through bores 13′ formed in the remaining half of the holders 10. Each bore 13′ corresponds to the diameter of the pin 11.
Thus, it is common to have two rack bars 7 per line pan 9. One rack bar 7b is fixed in the center of the line pan 9, and the second rack bar 7a spans the joint between adjacent line pans 9. Relative articulation between line pans during the mining process can cause the inter-pan gap to vary considerably and this could cause problems as the shearer drive sprocket 5 moves from the fixed rack bar 7b to the inter-pan rack bar 7a, if the inter-pan rack bar is firmly pinned to either adjacent pan. The common solution is for the inter-pan rack bar pins 11 to be retained in slots 13 in the clogs 10 rather than holes. In this manner, the error in tooth pitch between adjacent rack bars is halved and is kinder to the shearer sprocket 5, but causes added difficulty with pin retention, as the pin 11 must be allowed to move along the slot 13.
More particularly, as shown in
The clog 10 has a width corresponding to the width of the nose-shaped extension 12, and the clog 10 defines a cavity for engaging and providing support for the rack bar 7 by receiving the nose-shaped extension 12, the cavity being defined by two spaced apart bracket sidewalls 16, and end walls 17 connecting the sidewalls 16. The clog 10 also has openings 18 through the sidewalls 16, the pin 11 being insertable through one sidewall opening 18 and being received in the other sidewall opening 18.
The pin has a head 19 that is larger than the opening through the sidewall of the clog 10, so the pin 11 cannot pass through the clog 10. In order to retain the pin 11 within the clog 10, a retainer plate 20 is dropped into the area between the head of the pin 11 and the shield plate 14. The retainer plate 20 prevents the pin 11 from coming out of the clog 10.
Thus, as shown in
The primary role of the clog 10 is to provide fixing points on the line pans 7 for the semi-flexible rack bar system along which the shearer hauls itself in order to cut material from the seam. The nature of the system is that rack bars 7 are easily replaced if damaged, but the clogs 10 cannot be repaired in a hazardous environment, as the required cutting and welding is prohibited. Hence there is a need for a strong, reliable, simple rack-clog retention assembly.
It is an object of this disclosure to provide such a strong, reliable, simple rack-clog retention assembly.
This disclosure provides a rack bar system utilizes a forged or cast clog with integral lugs that accept a retainer plate. The plain rack bar pins cannot pass fully through the clog and are held in place by a plate retainer. The retainer is simply secured by a spring pin, or is held in place by gravity.
Before one embodiment of the disclosure is explained in detail, it is to be understood that the disclosure is not limited in its application to the details of the construction and the arrangements of components set forth in the following description or illustrated in the drawings. The disclosure is capable of other embodiments and of being practiced or being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. Use of “including” and “comprising” and variations thereof as used herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Use of “consisting of” and variations thereof as used herein is meant to encompass only the items listed thereafter and equivalents thereof. Further, it is to be understood that such terms as “forward”, “rearward”, “left”, “right”, “upward” and “downward”, etc., are words of convenience and are not to be construed as limiting terms.
This description takes as its starting point the typical longwall conveyor fitted with rack haulage, as described above, where a strong clog pin plate retention assembly is contained entirely within the clog. Changing the clog position on the line pan does not require any consequent change to the line pan.
More particularly, as illustrated in
The rack bar haulage system 100 also includes a clog 110 that has a width corresponding to the width of the nose-shaped extension 112, and the clog 110 defines a cavity 132 for engaging and providing support for the rack bar 107 by receiving the nose-shaped extension 112, the cavity 132 being defined by two spaced apart bracket sidewalls 116, and end walls 117 connecting the sidewalls 116. The clog 110 also has openings 118 and 138 through the sidewalls 116. A pin 111 is insertable through the sidewall opening 118 and the pin 111 is received in the other sidewall opening 138, the other sidewall opening 138 being smaller than the end 136 of the pin 111. The other sidewall opening 138 forms a pocket that receives the end 136 of the pin 111 that does not permit the pin 111 to pass through the other sidewall opening 138.
The clog 110 also includes means for receiving a retainer plate 120 for retaining the pin 111 within the first sidewall opening 118. The means for retaining the plate 120 comprises spaced apart lugs 121 attached to the one side of one of the sidewalls 116, the lugs 121 including opposed slots 140 that receive the ends of the retainer plate 120. The lugs 121 also include a retaining spring pin 144 or similar for retaining the plates 120 within the lugs 121.
In summary, the disclosed rack bar system 100 utilizes a forged or cast clog 110 with integral lugs 121 that accept a retainer plate 120. The plain rack bar pins 111 cannot pass fully through the clog 110 and are held in place by a plate retainer 120. The retainer is simply secured by a spring pin 144, or can be merely held in place by gravity.
The retainer plate is a simple, strong device to retain clog pins in one direction only. Note that the term plate only defines its general shape—it is not necessarily made from rolled plate and can be cast or forged.
The pin is plain on the prime proposal and requires no head for retention purposes. This is cost-effective.
Various other features of this disclosure are set forth in the following claims.
