Advanced freight car truck program - Vehicle Track Systems Newsletter

Railway Age, Dec, 1995

In 1995, AAR established a multi-year, industry funded program to promote improvements to the general fleet of freight car trucks. The program titled Advanced Freight Car Truck has been given priority as one of AAR's 14 Strategic Research Initiatives (SRI). This SRI has been split into two related research efforts titled Advanced Freight Car Truck--Design and Advanced Freight Car Truck--Wayside Defective Truck Detector. The long term goals for this project include improved trucks for heavy haul service and wayside detection strategies to detect poorly performing trucks in service.

The objective of the Advanced Freight Car Truck--Design Program is to foster a new and innovative generation of freight car trucks to replace existing three-piece trucks using a performance based design approach. The focus for the program in 1995 and 1996 is on improved suspensions for autorack cars. In future years the focus will change to other services.

Market retention (or growth) through improved ride quality performance is the key potential benefit from this program. The conventional three-piece truck design has served the railroad industry well for the past 50 years. However, it is failing to meet the increasing demands for dependable, reliable, and efficient transportation service from both customers and railroads. This is especially true in the transportation of finished automobiles. Although damage to automobiles transported by rail has been steadily reduced over the past several years, the automotive industry is demanding further improvement. Improvements to the longitudinal ride quality are being addressed by new draft gear designs and better train handling practices. Vertical and lateral ride quality improvements must be achieved through advanced freight car suspensions. Improved service quality and reduced operational costs would result from improvements to the multi-level autorack suspension.

Industry partnerships

Partnerships between the railroad and automotive industry have been established to identify performance objectives and pool available resources to address the relevant issues.

The automobile manufacturers and the railroad industry have created committees and focus groups to define the needs for finished automobile transportation. One of these, the Future Distributions Systems (FDS) Task Force, has investigated several alternative concepts to conventional autorack service. These alternatives were primarily focused on custom racks mounted in containers (or trailers) or on new multi-level car designs. An important product of the FDS program was the generation of a recommended practice for automobile transportation titled "Ride Quality Performance Requirements for Motor Vehicle Shipments."

The recommended practice is the first time that an agreement has been reached on how data is to be collected and analyzed. In addition, standard test and analysis cases were agreed upon for evaluating ride quality performance. These include controlled tests over specially constructed track anomalies, impact tests, and over-the-road tests on selected railroad property.

Another joint automotive and railroad industry committee, the Quality and Maintenance of Today's Equipment (QMTE) is being used as a forum for disseminating information obtained from the test program. QMTE meetings allow automobile industry comment on the suitability of the results. The QMTE committee has committed to funding 1996 testing at the TTC and in railroad service that will enhance the Advanced Freight Car Truck Program.

TTX company operates most of the multi-level autorack fleet. TTX and AAR have pooled resources to investigate the ride quality performance for the existing multi-level fleet when equipped with conventional or premium truck suspensions. TTX and AAR will participate in the economic and technical evaluation of proposed suspension designs.

Approach

A performance specification for a system of a bi-level car with an advanced suspension has been prepared to solicit new designs. This specification addresses safety and ride quality issues. Several AAR computer models will be used to calculate the potential merit of proposed designs. Economic performance will be evaluated using a range of models designed to determine costs due to track damage, fuel consumption, maintenance, and operational efficiency. Safety and ride quality performance will be evaluated using AAR's vehicle dynamics model NUCARS. NUCARS is a multi-purpose dynamic simulation model first developed to address safety issues in the 1980s.

This year TTX and AAR are cooperating in a program of test and analysis to determine baseline ride quality performance for a bi-level autorack car using a conventional three-piece truck and two premium truck designs. The same bi-level car will be used as the standard vehicle for evaluating new suspension concepts. NUCARS models of the bi-level car and the suspensions tested in 1995 have been constructed. The bi-level simulation is available to assist designers and will be used to evaluate designs submitted to the Advanced Freight Car Truck Program. In 1996, prototype testing of a new suspension selected by this analysis will be conducted. Figure I shows the standard bilevel autorack car.