Traditional LRV Side-Load Requirements and Their Applicability to Low Floor Cars

The focus of this paper is to study the application of Light Rail Vehicle (LRV) side-load requirements to Low Floor LRVs (LF LRVs). Although the side-load requirements of LRVs are not completely consistent among different transit authorities, an industry pseudo-standard of 40,000 lbs applied over an 8 foot span at the side sill has emerged. In LF LRVs, this standard may not provide the same level of safety as in High Floor LRVs (HF LRVs). In some US automobiles, the bottom of the bumper is higher than the top of the floor in LF LRVs. Given comparable sidewall construction, when a passenger vehicle impacts the side of an LRV, the opportunity for intrusion/override into the passenger compartment in a LF LRV is higher than that in a HF LRV. The popularity of light trucks, SUVs, minivans and other vehicles with high bumper heights further aggravates this situation.

Development of a Self-Contained Sensor Bearing for Rail Applications

This paper discusses bearing borne sensor system development efforts for use in monitoring the rail bearing and connected mechanical system. The measurement of speed, temperature, and vibration are considered. In the area of vibration analysis, particular emphasis is placed on the use of computationally efficient algorithms for use in parameterization of the vibration signal. Results from laboratory test data are presented. Finally, the relative merits of a wired versus a wireless communication channel, at the bearing level, are discussed.

Thermal Crack Development and Wheel Useful Life

The impact of thermal crack development on the wheel useful life was investigated. The actual data from the “Railroad” has been actively and intensely reviewed. Initial efforts were concentrated on the wheel metallurgy, thermal crack development mechanism and maximum allowable operating speeds on each line. Recent efforts have concentrated on the braking control and associated equipment configuration. The effect of worn wheel and repetitive braking was also investigated. However, it is difficult to postulate alternative approaches to managing wheel useful life without completely identifying existing operating policies and maintenance procedures, and without establishing measurable results of such policies/procedures. It is also crucial to understand the physical process involved. This process will be repeated with every brake application in combination with the residual compressive stress (due to rolling and battering of the wheel on the rail and by rim-quenching) causing the cyclic stressing of the material due to thermal expansion, i.e., “thermal fatigue”. Higher brake rate and higher tread to disc brake ratio lead to higher temperature gradient and higher compression stresses (higher portion of stress in plastic range). In addition, the microstructure change in the surface zone material involves additional uncertainty, i.e., the existence of material of unknown physical properties (perlite transformation in to spheroidite). The presence of spheroidite is a good indication that a wheel tread has been subjected to direct thermal damage. It is a common conclusion based on two completely independent research projects that the combination of heat and compression increases hardness and yield strength. The maximum wheel temperature has a major impact on microstructure changes of the wheel surface layer. Also a smaller wheel diameter yields to higher maximum tread temperature. Various studies relating new and worn wheel clearly show the impact.

On the Application of Magneto-Rheological Fluid Technology for Improving Rail Vehicle Dynamics

The primary purpose of this paper is to review the fundamentals, concepts, and merits of new technologies that hold a promise for helping the railroad industry in its missions. The author hopes that this paper will be the first of a series of papers that will be devoted to reviewing new technologies that are on the horizon and can benefit the rail industry, in a manner similar to the current papers that report on the progress of different aspects of transit and passenger cars, locomotives, and freight cars. The fundamental difference between this paper and current papers is that it will be devoted to new technologies that are in a more distant horizon (10–15 years), as opposed to the more immediate future developments that are covered in current papers. The first technology that will be highlighted is the magneto-rheological (MR) technology that has received a tremendous amount of attention in the past five years in the transportation industry, in particular for automotive applications. This paper will provide an overview of MR technology and its common applications, and provide some fruits for thoughts on how MR technology can be used in the rail industry.

Computer Controlled Braking System for Amtrak High Speed Trainsets

The new Amtrak High Speed Trainsets used in ACELA Express service on the Northeast Corridor are equipped with an advanced microprocessor controlled braking system with full pneumatic control back-up protection. The system is designed to provide high reliability, to prioritize high levels of electric braking from power cars on each end of the trainset and to fully blend electric braking effort with the pneumatic friction braking effort of the entire trainset. This type of control which optimizes power conservation through regenerative braking and decreases wear and thermal stress on friction brake components is similar to that used on the German Railways ICE trainsets but is totally new and unique to North American inter-city rail vehicles. This paper will describe the system, special components and performance of this equipment.

The Advanced Handbrake Actuator System

State-of-the-art freight car handbrakes are manpower intensive. Setting and releasing handbrakes expose operators to safety hazards and the potential for human error exposes train operations for possible time delays, mild to severe maintenance issues and ultimately the potential for major rail accidents. In response to the need to reduce the hazard associated with freight car handbrakes, UTD has developed the Advanced Handbrake Actuator System (AHAS), a fail-safe powered handbrake device, accessible from ground level on either side of the car. The AHAS concept was developed, manufactured and demonstrated under sponsorship of the Federal Railroad Administration (FRA) Small Business Innovation Research (SBIR) program. The system is designed to replace existing handbrake wheels and provide significant improvements by offering new ways of applying or releasing the brake. Remote electronic signal, car mounted hand levered pneumatic valve, and a manual hand crank mechanism, requiring significantly less effort than that required by the state-of-the-art handbrake wheel, constitute three methods of actuation. The AHAS is comprised of a compression coil spring arranged to apply tension to the handbrake chain as its default condition. Two release systems are available. The first uses an air cylinder actuator connected in series with the spring and chain. Applying air pressure by remote or local command will compress the spring and release the handbrake. The spring may also be compressed to release the handbrake by a hand crank mechanism, accessible from ground level on either side of the car. The AHAS is equipped with a dedicated air reservoir charged with compressed air prior to departure via the train’s brake pipe. The AHAS was successfully field tested on a freight car in regular service over a period of three months and was found to be user friendly and safe, logging over 120 successful operations.

Analysis of Wheel-Rail Elasto-Plastic Contact Problem

Using the finite element parametric quadratic programming method, computation of Elastic and Elastic-plastic rolling contact problems between wheel and rail is carried out for various cases such as different wheel diameters, different axle loads, different tractive force and different friction factors. The contact states and the contact internal force between wheel and rail are obtained, and their changing laws corresponding with every above-mentioned parameter are analyzed in this paper.

Some Possible Alternatives for Longer-Life Locomotive Wheels

An increase in the wear life of locomotive wheels is considered desirable from the locomotive builder and railroad user points of view. If a wheel has a longer service life, economics are improved due to less locomotive out-of-service time, reduced maintenance repair costs and reduced wheel renewal costs. This paper discusses possible alternative materials and microstructures that could be used for longer-life locomotive wheels, and also tires. If locomotive builders and users consider wheel rim hoop compression essential, then microalloying and increased carbon content are perhaps the most likely courses of action to improve wheel life. If rim hoop compression is not considered essential, a wide range of alternatives become possible including bainitic and martensitic microstructure monobloc wheels and tires.

LRV Compression Loads: Statistical Data and Recommendations

Carbody compression resistance is a major LRV safety feature in head-on collisions. Regrettably, one of the difficulties in writing LRV specifications has been establishing credible values for the design compression loads that the carbody shall demonstrate to resist. One reason for this difficulty is that setting compression loads involves judgment and therefore is to a great degree subjective. The other is that vehicle engineers have been setting design compression loads in relative isolation from each other, without the benefit of a broader discussion among them. This paper will attempt to reconcile the various positions and, based on statistical data, will recommend median values for compression loads as a function of carset kinetic energy.

Progress in Railroad Freight Car Engineering

Every year the Rail Transportation Division (RTD), American Society of Mechanical Engineers (ASME) conducts a survey to document progress in the design, construction and use of freight cars and components. This paper describes the new developments. Some information was obtained from web sites. The industry continued to focus on the evolution of freight equipment in 2002 by adding flexibility and versatility to designs developed in the recent past. Due to a slow down in new car building fewer responses were received.