Freight Truck for Higher Speed Operations

Abstract

The current freight railroad operations are restricted to a maximum speed of 80 mph partly due to lateral instability of conventional freight trucks at higher speeds. The three-piece truck, a workhorse of the railroad industry for over 100 years, and its variations are susceptible to hunt at 50–55 mph when empty and 90–100 mph in loaded conditions. Design attempts to increase high-speed stability generally lead to diminished curving performance and increased risk of derailment. In this paper we describe a true pendulum suspension based freight truck that is designed to achieve stable operations up to 150 mph without compromising curving performance. The truck’s performance has been analyzed using an industry standard vehicle dynamics simulation tool. The AAR MSRP M-1001 Chapter 11 ‘Service-Worthiness Tests and Analyses For New Freight Cars’ were used to qualify the design where applicable. Traditional tread brakes are supplemented with axle-mounted disc brakes to provide safe braking capabilities beyond 110 mph. Two full-size 70-ton prototypes have been assembled using off-the-shelf and fabricated components. Yard tests have shown that the truck curves properly even under very tight curving conditions.