Integrated Railmotive Systems Inc.

Excellence in Engineering

NEW TRUCK DESIGN FOR IRON HIGHWAY
    
   As detailed in webpage 23 the original Iron highway used short platforms that were articulated together on two wheel trucks. Each truck supported the B end of one platform directly on four rubber springs which accommodated both the vertical and lateral deflections normally associated with any suspension. The semi-permanent connection of the platforms to each other was, and is, made by a spherical connection carried on the B end of the platform. This is enclosed by a pair of “clam shells”, carried by the A end of the adjacent platform. When these are brought together they form a female spherical connector, as shown in Exhibits 22.1 and 22-2.
    Finally a pivot pin carried atop the truck guides the articulation to follow the truck as it moves along the track. This pin is captured within the rubber lateral spring that is pressed into the hollow center of the male centering sphere as shown below. This lateral spring provides a flexible fixing for the pivot pin in the articulation, and determines the lateral and longitudinal spring rates of the platform. The lateral spring (along with its attached platform ends) is also free to slide vertically on the pin so as to permit the relative vertical motion of the platform at a rate determined by the four suspension springs. This freedom is provided by allowing the pin to slide in a bronze bushing, molded into the lateral spring which is carried in the bore of the spherical connection.


Exhibit 22-1 truck assembled to “B” end of IH platform Adjacent platform raised to show assembly order
     The iron highway, being a continuous articulated platform, had no centerplate, draft gear or coupler, so the pivot pin serves only to transmit forces to and from the truck.    

    The A end of the next platform rests on the B end structure which as mentioned, is supported by the truck. This A end is supported by two Manganese bronze bearing shoes riding on stainless steel wear plates carried on the surface of the B end platform near the extreme width of the platform, as shown in the exploded view of  exhibit 22-2 below.



Exhibit 22-2 Exploded View of both platforms, Truck assy, draft connection and vertical support in assembly order
A final important feature of the original two wheeled truck was the provision of the forced steering mechanism. This mechanism included  a system of steering rods and levers which, as the platforms angled when rounding a curve, forced the truck to angle equally with respect to each platform, thus splitting the angle between them.  This assured that the wheel flanges would always be forced to be parallel with the rails on which they ride; thus giving security against derailment, because a wheel cannot climb a rail that it cannot develop an angle of attack against.
    The combination of the several features above and the low platform height achieved, worked to provide both excellent safety and ride quality as well as low maintenance costs.


Exhibit 22-3 New 4 wheel IH truck
When the Iron Highway equipment was purchased by an Australian firm, they desired to keep all of the unique features of the platforms and suspension because of the smooth continuous roadway they provided for trailer loading and unloading and the excellent ride quality that the truck and articulation had demonstrated. There was, however, a daunting problem.
      The railways of Australia were built to support much lighter equipment than those of North America, and the Iron highway had been designed at the extreme limit of the much more heavily built North American system. Thus the Australian railways could not accept the original two wheeled truck around which the platforms had been designed.
    Because of Railmotive’s extensive knowledge of the IH and its truck and articulation, we were able to suggest a simple solution.  The wheel loading could be halved by using two axles, closely spaced and with smaller diameter wheels, but with a unique truck design could retain all of the important features of the original two wheeled truck. The proposed truck, shown in exh. 22-3 would in fact be interchangeable with the original two axle design, thus minimizing the platform alterations necessary to permit  its use.
    The new truck would use the same springs, and layout as the original, would maintain the forced steering feature the freedom from metal to metal wear.  To accomplish this we proposed a 28” wheel diameter, AAR “D” narrow bearings and inside bearing mounting. The design was finalized and its dynamic performance checked using the expertise of Dr. F.B. Blader of Transangle Corp. While the several custom rubber components were checked and produced by LL Kurtz Corp. Patent has been applied for by Railmotive,

    The first ten prototypes of the new truck are presently under construction by CR Technologies of Melbourne Australia.