Patent Publication Number: US-4728030-A

Title: Railway sleeper with spade-like end contours

Description:
This application is a continuation of application Ser. No. 735,486, filed May 20, 1985, now abandoned. 
    
    
     This invention relates to railway sleepers, and more particularly relates to channel-section metal sleepers having downwardly inclined `spade` ends. 
     Conventional spade end sleepers which have their plain upper surfaces downwardly inclined at an angle of between say 40° and up to 90° to the horizontal, suffer from the drawback that loads cannot readily be sustained closely adjacent these ends, because they `dig in` to the ballast in response to sideways movement, they cannot be readily replaced for maintenance purposes, etc., and with steep angled ends they do not readily stack. 
     It is an object of this invention to provide an improved sleeper which mitigates the above problems. 
     According to the invention there is provided a railway sleeper having a formed inverted channel-shaped section the ends of which have their upper surfaces downwardly inclined and shaped in a corrugated fashion to add strength and rigidity to said ends. 
     According to the invention there is further provided a railway sleeper having a formed inverted channel-shaped section the ends of which have their upper surfaces downwardly inclined and so shaped to progressively define at their extremities, in end elevation, a serpentine path having downwardly inclined portions at the side and two further such portions inwardly thereof. 
     The `dished spade` end contour of the sleeper may be pressed from a standard rolled steel channel section. By virtue of the stronger ends thus produced these portions can sustain a greater load than the conventional design hitherto--this means that the length of the sleeper according to this invention may be much shorter, e.g. 20% less than the conventional design for the same load bearing capacity, representing a considerable cost savings. The shape facilitates stacking, and lateral insertion beneath the track for track maintenance and replacement, etc., and although the end design is such that it affords less restraint against lateral load thrusts it is still 50% or so greater than the standard concrete or wooden sleeper. 
    
    
     In order that the invention may be fully understood one embodiment thereof will now be described with reference to the accompanying drawings in which 
     FIG. 1 is a longitudinal section on the centre line of a sleeper according to the invention; 
     FIG. 2 is a plan view of the sleeper of FIG. 1 (without the rail); 
     FIG. 3 is a section on A--A in the above Figures; and 
     FIG. 4 is an end elevation of FIG. 2. 
    
    
     Referring now to FIG. 1 and 2 in the drawings a steel sleeper 1 has welded to it a rolled steel base plate 2 which in the example shown has an inwardly sloping upper surface such as to support a rail 3 in a tilted fashion. The body of the sleeper is roll-formed and then the end is press-formed in a manner such that the upper surface 4 is inclined downwardly and so shaped as to progressively define at its extremity a serpentine or sinuous configuration, the sleeper being of a consistent width and continuous form along its entire length. 
     This is better illustrated in FIG. 4 where it can be seen that it approximates to an undulating path extending over 11/2 cycles. The sides each have upwardly inclined surfaces 5, 6 merging into a U-shaped central section having downwardly inclined surfaces 7, 8. 
     Four `upright` portions are thus manifested by this form of construction, significantly strengthening the sleeper ends giving rise to the advantages claimed above. 
     To give a practical example on the above, with a 1435 mm track gauge, the overall sleeper length may be 2,300 mm, the as-rolled section (FIG. 3) with side wall thickness of 6.75 mm may have a weight of 27 kg/meter with the total weight of the sleeper as pressed in the normal industrial sleeper grade steel being 62 kg. 
     Although the invention has been described with reference to the particular embodiment illustrated, it is to be understood that various modifications may readily be made without departing from the scope of this invention. For example, the precise shape and size of the strengthened `corrugated` ends may differ from that shown compatible with the objects as recited above.