Securing Brake Shoes to Brake Beams in a Railroad Car Retarder

Abstract

Several embodiments of a system for connecting brake shoes to brake beams in a railroad car retarder all provide enhanced connecting joint tightness that reduces premature connecting joint loosening, reduces maintenance, and reduces failure of connecting bolts or equivalent connecting pins.

1 . A system for bolting brake shoes to brake beams in a railroad car retarder wherein the brake shoes have a generally inverted L-shaped cross section including a vertical web and a horizontal contact bar, and a vertical bolting face opposite the contract bar adapted to engage a mounting face on a connecting flange on the brake beam, the system comprising:
 elongate horizontally extending blind slots in the vertical web of the brake shoe, said slots extending linearly along the web and positioned in spaced relation, the slots having coplanar bottom surfaces and flat parallel opposing side faces lying in respective common planes, through bores in the slots extending perpendicular to the bottom surfaces and aligned with through bores in the connecting flange of the brake beam;   a headed grade 8 bolt for each aligned pair of through bores, said bolts positioned with the bolt heads in the slots and having opposite parallel bolt head faces dimensioned to provide a close clearance fit with the side faces of the slot;   said bolts having threaded shanks for receipt of nuts threaded on the ends thereof to engage the vertical outside face of the brake beam connecting flange;   whereby the engagement of the bolt head faces with the side faces of the slots permits bolts to be tightened to grade 8 level and a uniform clamping torque to be applied to the bolts sufficient to prevent relative rubbing movement and loosening of the connection between the brake shoes and the brake beams in use.   
     
     
         2 . The system as set forth in  claim 1  wherein the headed bolts comprise square-head bolts. 
     
     
         3 . The system as set forth in  claim 1  wherein the blind slots comprise milled slots. 
     
     
         4 . The system as set forth in  claim 1  wherein the slots are milled to define semi-cylindrical ends joining the side faces of the slots. 
     
     
         5 . The system as set forth in  claim 1  wherein each brake shoe is attached to the end halves of adjacent brake beams. 
     
     
         6 . The system as set forth in  claim 1  wherein each brake shoe is attached to and runs coextensively with a brake beam. 
     
     
         7 . The system as set forth in  claim 6  wherein the adjacent ends of adjacent brake shoes are provided with a tongue and groove arrangement operable to provide restrictive engagement and transfer of loading applied as a result of uneven movement of adjacent brake beams. 
     
     
         8 . The system as set forth in clam  6  wherein brake beams are tied together with a resilient connection. 
     
     
         9 . The system as set forth in  claim 8  wherein the resilient connection comprises a leaf spring arrangement. 
     
     
         10 . The system as set forth in  claim 9  wherein the leaf spring arrangement comprises:
 aligned recesses formed in the adjacent ends of the brake beams; and,   a plurality of leaf spring layers positioned in the recesses and spanning the space between said brake beam ends.   
     
     
         11 . An improved system for connecting brake shoes to brake beams in a railroad car retarder wherein the brake shoes have a generally inverted L-shaped cross section including a vertical web and a horizontal contact bar, and a vertical attachment face on the vertical web opposite the contract bar adapted to engage a mounting face on a connecting flange on the brake beam, the system comprising:
 a connection arrangement selected from the group consisting of (1) bolts extending through horizontal bores in the brake beam mounting face and threaded into tapped holes in the attachment face of the brake shoe, (2) pins extending through bores in the brake beam mounting face with a close clearance fit and into blind holes in the attachment face of the brake shoe with an interference fit, (3) pins extending through bores in the brake shoes with a close clearance fit and into holes in the brake beam with an interference fit; and (4) square-head bolts with bolt heads received in horizontal slots in the brake shoe web with a close clearance fit and bolt shanks extending through aligned pairs of through bores in said brake shoe attachment face and said brake beam connecting flange and nuts threaded on the bolts against the vertical outside face of the brake beam connecting flange;   whereby the selected arrangement provides a fixed connection between the brake shoe and the brake beam adequate to prevent relative rubbing movement between the brake shoes and brake beams and loosening of the connections.   
     
     
         12 . The system as set forth in  claim 11  wherein each of said connection arrangements is installed from the field side of the retarder by one person. 
     
     
         13 . The system as set forth in  claim 11  wherein each brake shoe is attached to and runs coextensively with only one brake beam. 
     
     
         14 . The system as set forth in  claim 13  wherein the adjacent ends of adjacent brake shoes are provided with a tongue and groove arrangement operable to provide restrictive engagement and transfer of loading applied as a result of uneven movement of adjacent brake beams. 
     
     
         15 . The system as set forth in  claim 13  wherein adjacent brake beams are tied together with a resilient connection. 
     
     
         16 . The system as set forth in  claim 15  wherein the resilient connection comprises a leaf spring arrangement. 
     
     
         17 . The system as set forth in  claim 16  wherein the leaf spring arrangement comprises:
 aligned recesses formed in the adjacent ends of the brake beams; and,   a plurality of leaf spring layers positioned in the recesses and spanning the space between said brake beam ends.   
     
     
         18 . The system as set forth in  claim 16  wherein the leaf spring layers are retained in operative position by a retarder system operating lever. 
     
     
         19 . The system as set forth in  claim 11  wherein the connection arrangement having bolts extending through horizontal bores in the brake beam mounting face and threaded into tapped holes in the attachment face of the brake shoe comprises horizontal bores providing a close clearance fit with the bolts. 
     
     
         20 . The system as set forth in  claim 11  wherein the connection arrangement having pins extending through bores in the brake beam and into blind holes in the brake shoe includes supplemental threaded bolts positioned between and in linear alignment with the pins to assure contact between the contact face on the brake shoe and the mounting face on the brake beam. 
     
     
         21 . The system as set forth in  claim 11  wherein the horizontal slots for receipt of the heads of the square-head bolts comprise milled slots having flat parallel opposing side faces providing the close clearance fit with opposite bolt head faces. 
     
     
         22 . The system as set forth in  claim 21  wherein the milled slots have a depth approximately equal to the thickness of the bolt heads in the axial direction.