Patent Publication Number: US-7896179-B2

Title: Knuckle pin for railway vehicle coupler

Description:
FIELD OF THE INVENTION 
     This invention relates to a pin for use in a railroad car coupler assembly. 
     BACKGROUND OF THE INVENTION 
     Knuckle coupler assemblies are well known in the railway industry to attach one railroad car to another. Each railroad car to be connected to another railroad car has a coupler. The two couplers of adjacent railroad cars that are about to be coupled each have a knuckle attached to them. When the couplers go together and become coupled, the knuckles snap closed. Thus, you have two couplers, two knuckles, and two thereby formed apertures for the knuckle pins to slip into. A railroad pin is inserted into the through apertures of the knuckles to lock shut the knuckles and secure the connection between the two railcars. However, over time, the alignment of the apertures formed by the connection of the two knuckles and coupler bodies are difficult to attain because of metal wear. Misalignment of the apertures of the knuckle and coupler body reduces the area size of the overall aperture for receiving the railroad pivot pin, making installation of the pin more difficult and potentially hazardous to the railroad worker during connection of the railroad cars. 
     In addition, cotter pins have been previously used to hold the pivot pin within the aperture of the railroad car coupler. The continued motion of the railroad cars can wear into a specific area of the pin which can cause fatigue and breakage of the cotter pin material. 
     Another disadvantage of using a cotter pin to secure the pivot pin within the railroad coupler is that installing or removing the cotter pin can be difficult and dangerous to the railroad worker. 
     SUMMARY OF THE INVENTION 
     It is the intent of the subject invention to address some of the aforementioned concerns. According to one aspect of the invention a knuckle pin retainer is provided for a railroad car coupler including a pivot pin having an elongate shaft with an exterior surface extending between a first end and second end of the elongate shaft. The first end has a head disposed at the terminating end having an arcuate exterior surface. The arcuate surface terminates at a lip integrally formed to the elongate shaft. The elongate shaft has a constant diameter from the lip of the head to the terminating end of the second end. The elongate shaft further includes a cylindrical slot positioned proximate to the second end which extends through the exterior surface of the shank generally diametrically and terminating before the opposing diametric exterior surface of the shank. A retractable spring-loaded retaining member is disposed within the cylindrical slot. 
     The invention provides an improved knuckle pin retainer for installation in a knuckle coupler assembly for securing the connection of two adjacent railroad cars that addresses the aforementioned concerns. 
     Other applications of the present invention will become apparent to those skilled in the art when the following description of the best mode contemplated for practicing the invention is read in conjunction with the accompanying drawings 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The description herein makes reference to the accompanying drawings wherein like reference numerals refer to like parts throughout the several views, and wherein: 
         FIG. 1  is a schematic view of a railroad car coupler incorporating a knuckle pin retainer having a retaining member according to the present invention; 
         FIG. 2  is a side sectional view of the knuckle pin retainer illustrating certain details of the retaining member and an associated spring; and 
         FIG. 3  is an elevational view of the retaining member compressed in the knuckle pin retainer. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The knuckle pin retainer  20  of the present invention is provided to lock a railroad coupler  10  together to securely connect adjacent railroad cars. Referring to the drawings,  FIG. 1  shows a schematic of railroad car coupler  10  which can include a yolk  12  and coupler  14 . The yolk  12  and coupler  14  interconnect and are secured together by the knuckle pin retainer  20 . The yolk  12  and coupler  14  interconnect and form a through aperture  16  therebetween for receiving the knuckle pin retainer  20 . The connection of the knuckle pin retainer  20  to the railroad car coupler provides pivotal motion of the connecting railroad cars relative to the adjacent railroad cars. 
     Referring to  FIGS. 1-3 , the knuckle pin retainer  20  includes a pivot pin  22  and a spring-loaded retaining member  24 . The pivot pin  22  includes a shaft or shank  26  and a head  28 . The pivot pin  22  is made of a solid steel material. The shaft or shank  26  terminates at the head  28 . The head  28  is essentially dome shaped. The head  28  is diametrically larger than the diameter of the shaft  26  and the through aperture  16  to provide a stop for the knuckle pin retainer  20  when installed in the through aperture  16  of the railroad car coupler  10 . The shaft  26  is a solid cylindrical body preferably made of a treated steel material. The shaft  26  is size to extend beyond the railroad coupler  10  when installed and to have a predetermined length exposed below the coupler for exposure of the retaining member  24  below the railroad coupler  10 . The pivot pin  22  can rotate 360° to provide easy installation and removal and further to provide even wear along the axial length of the shaft  26 . 
     At the free end  32  of the shaft  26 , a slot or aperture  30  diametrically traverses the shaft  26 . The aperture  30  does not extend through to the opposing surface of the shaft  26 , but terminates at a point  34  adjacent to the diametrically opposing surface from the opening  36 . The opening  36  to the aperture  30  has a circumferential distortion concentric and wider than the diameter of the remainder of the aperture  30 . In the illustrated embodiment the circumferential distortion at the entry or opening  36  to the aperture is a beveled edge. The beveled opening  36  facilitates rotatably pressing a retaining member/latch pin  24  into the aperture  30 . The beveled opening  36  terminates at a radial point  38  defining a shoulder with a reduced diameter commencing just inside the peripheral outer surface of the shaft  26 . The radial point  38  forms a stop to prevent the retaining member  24  from inadvertently escaping the aperture  30  during use. 
     A spring  40 , preferably made of stainless steel, is disposed within the aperture  30  and positioned adjacent the terminating pointed end  34  of the aperture  30 . The aperture  30  is coated or filled with a lubricant, such as grease or oil at the spring  40  location to facilitate the compression and expansion of the spring  40 . The lubricant also prevents corrosion from water or dirt; and further prevents winter freeze up. 
     The retaining member/latch pin  24  is rotatably pressed into the aperture  30  so that a rear surface  42  of the latch pin  24  lays against a first end surface  44  of the spring  40 . The retaining member  24  has a tubular main body  48  with a constant diameter along the axial length of the main body  48 . The diameter of the main body  48  is slightly smaller than the diameter of the aperture  30  between the radial point  38  of the beveled opening  36  and the beginning of the taper for the pointed distal end  34 . Clearance between the outer surface of the retaining member  24  and the wall defining the aperture  30  allows for rotatable movement of the retaining member  24  within the aperture  30 . The diameter of the main body  48  of the retaining member/latch pin  24  is predetermined to allow the latch pin  24  to rotate within the aperture  30 . The rotatable attribute of the latch pin  24  minimized wear on the latch pin  24  during use. The rotational movement of the spring-loaded latch pin  24  also allows for the latch pin  24  to rotatably maneuver within the cavities (not shown) in the wall of the aperture  16  formed by the yolk  12  and coupler  14 . Further the ability to rotate facilitates the entry and removal of the retaining member/latch pin  24  from the aperture  30 . 
     The retaining member/latch pin  24  further includes a nose portion  50  integrally formed at the front end  49  of the main body  48 . The nose portion  50  has a reduced diameter from the main body  48 . The diameter of the nose portion  50  is constant until it terminates at the ball nose  52  which has an arcuate end surface with a radius equaling the radius of the nose portion  50 . The arcuate end surface of the ball nose  52  allows the retaining member  24  to easily slide within the through aperture  16  and its cavities (not shown) of the railroad car coupler  10 . As the retaining member  24  enters and leaves the coupler  10 , the rotational ability of the latch pin  24  minimizes wear along any single surface of the latch pin  24 . 
     Further, as the latch pin  24  enters the through aperture  16  of the coupler  10 , the arcuate surface of the ball nose  52  glides over the entry edges to the aperture  16  to prevent nicks and gorges to the latch pin  24 . This is especially advantageous when the latch pin  24  has not been fully depressed into slot  30  before the knuckle pin retainer  20  is inserted into the aperture  16  of the coupler  10 . 
     In the prior art, cotter pins have been used with the knuckle pin retainer  20 . However, cotter pins do not have the ability to rotate and therefore quickly wear along one surface area during use and when requiring replacement. Further cotter pins require additional manual labor to insert the cotter pin after the pivot pin  22  is installed. 
     The lengths of the retaining member/pin  24  and spring  40  with the described configuration are such that when the spring  40  is in its normal biased position, the nose portion  50  extends beyond the beveled opening  36  of the aperture  30 . In the biased position, the spring  40  urges the retaining member  24  out of the aperture  30 . The front end  49  of the main body  48  of the latch pin  24  is stopped by the reduced diameter formed at the radial point  38  of the beveled opening  36 . The radial point  38  anchors the retaining member/latch pin  24  and prevents inadvertent removal of the latch pin  24 . 
     The retaining member/latch pin  24  is made of a corrosive resistant material that is plated with a zinc or cadmium material with a di-chromate bake. The resultant latch pin  24  has a gold or yellow hue that is highly visible in contrast to the steel material of the remaining components of the knuckle coupler. This is especially useful during inspection of the railroad cars to check the condition of the latch pin  24 . The material of the retaining member/latch pin  24  also provides anti-corrosive properties. 
     When the shaft  12  is installed in the railroad car coupler  10 , the retaining member  24  is retracted into the aperture  30  and thereby compresses the spring  40 , as shown in  FIG. 3 . Once the retaining member  24  clears the aperture  16  of the railroad car couple  10  the spring  40  again biases the retainer member  24  away from the pointed end  34  of the aperture  30  so that the nose portion  50  is exposed out of the aperture  30 +In this manner the railroad worker does not have to physically install a cotter pin into the shaft  26 . When the nose portion  40  is exposed, vertical movement of the railroad coupler  10  is minimized or prevented. To remove the pivot pin  22  from the railroad coupler  10 , the retaining member  24  is depressed against the spring  40  while the pivot pin  22  is raised out of the aperture  16  of the coupler  10 . Time and manual expense is reduced in the installation of the pivot pin  22  of the present invention. Further, additional tools are eliminated for the installation and removal of the knuckle pin retainer  20 . The knuckle pin retainer  20  of the present invention provides for easy and safe installation and removal that requires minimal manual labor and tools. 
     While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed embodiments but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims, which scope is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures as is permitted under the law