The Effect of Friction Modifiers on Wheel/Rail Isolation

Train detection, for signalling purposes, is often by means of track circuits. Signalling block occupancy is triggered by the wheelset of the train ‘shorting out’ the track circuit, i.e. the wheels and axle act as a shunt. Contamination on the track such as ballast dust, rust, oil, or leaves as well as substances designed to improve train operation such as friction modifiers or sand may cause the contact between the wheelsets and the track to be compromised, inhibiting train identification. In previous work a twin disc approach has been used to study the effect of sand (used to improve adhesion) and leaves on wheel/rail isolation. Friction modifiers are of significant current interest in wheel/rail research. Introducing a new material into the tread/top of rail interface can raise questions about the impact on signalling systems. Although no significant effects have been observed in practical operation on a range of railway systems, the intention in this work was to evaluate conductance between wheel and rail in a more controlled and systematic fashion using the previously established methodology. Using the twin disc technique, friction modifier, in the form of a solid stick, was applied using a spring loaded device to the rotating wheel disc to generate a visible film. Tests were run to measure contact impedance at typical loads and slips. Static tests were also carried out using discs pre-conditioned with a friction modifier film. The electrical circuit used was a modified simplified simulation of audio frequency track circuit. No significant difference was observed in the measured impedance for dry conditions with no friction modifier, versus tests where friction modifier was applied, regardless of percentage slip or input voltage. The analysis suggests that the introduction of friction modifier into the existing wheel/rail interfacial film does not result in increased impedance with all other factors being equal.

A Rail Mounted Ultrasonic Sensor for Contact Patch Measurement

Failure of a wheel/rail contact is usually by wear or fatigue and both of these depend on the size and location of the contact patch. One contact measuring approach that shows promise is by the use of ultrasonic reflection. If the wheel and rail surfaces make contact and are under high stress they are more likely to transmit an ultrasonic pulse. However, if there is no contact or the contact is under low stress then the wave is completely or partially reflected. By measuring the proportion of the wave reflected it is possible to deduce the extent of the contact area and also estimate the pressure distribution. In previous work [1] static specimens of wheel and rail were measured by scanning a transducer to build up a 2D map of the contact. Whilst this produced good results and agreed well with contact modeling, it is a time consuming process (typically takes 30 minutes for a scan) and could in no way be used for the measurement on-line. In this paper we describe a method that potentially could be used at line speeds and so provide wheel rail contact measurements in field trials. The 2D scan is achieved by using an array transducer that performs a simultaneous line scan. This coupled with the speed of travel of the contact patch over the sensor location can achieve a map of the contact. Specimens were cut from wheel and rail sections and loaded together hydraulically in a biaxial frame. An array transducer was mounted beneath the rail specimen. The array transducer consisted of 64 ultrasonic elements that may be pulsed independently, simultaneously, or with controlled phase difference. In this work all transducers were pulsed simultaneously at repetition rates of 20 kHz. The signals were reflected back from the contact to effectively produce a line scan. The transducer was physically moved, to simulate the translation of the contact patch and so generate a series of reflection profiles. Contacts under a range of normal and lateral loads have been measured and compared with some simple results using pre-inked paper. The paper concludes with a discussion of how this array measurement procedure might be implemented at full line sped and what accuracy could potentially be achieved.

Design of an Intelligent Remote Monitoring and Control of Bangladesh Railway Transport System Using Information and Communication Technologies (ICTs)

In Bangladesh, transport sectors are developing rapidly to meet the increasing demand for transporting passengers and freight inside and outside the country. But there is not such development in railway transport system. The Bangladesh Railway transport system is still using an old technology to monitor and control signalling, scheduling, operations etc. This paper describes various problems in the existing systems and also solutions have been provided considering the existing railway transport systems of Bangladesh. A new system has been developed to control and monitor the total railway transport system from remote locations. While designing the system, various sensors and actuators have been introduced and also Information and Communication Technologies (ICTs) have been applied in the field of railway transport. So a Machatronics aspect of system has been designed to ensure a collision free, safe and efficient operation and management of railway transport system. This system is not only for monitoring and controlling of railway transport but also ensures efficient asset management. As a result face-to-face accidents, cross-road accidents and accidents due to railway line displacements or breakage can be avoided and there will be no loss of assets and valuable human lives.

Effect of Bolt Strength and Loading Conditions on a 7/8” Bolt Within an End-of-Car Arrangement

A cause of failure within end-of-car (EOC) arrangements for cushioned cars with F-shank couplers is that of the yoke bolt failing in shear. This mode of EOC failure is of particular concern due to the concealed nature of the bolt not easily allowing for early detection of the onset of failure. To this end, a finite element analysis (FEA) was performed on a 7/8” bolt and F-bracket assembly to determine the stress state developed within the bolt in an effort to understand the potential cause or causes for the bolt failure. Several parameters, including bolt strength, bolt preload (initial torque), and external loading were varied to determine their effects on bolt performance. The subsequent results indicate that both inherent strength and initial preload have a significant effect on whether a bolt can effectively withstand the various external loading conditions encountered in the field. In addition, it is also apparent that some of the simulation loading scenarios analyzed contain the potential to initiate bolt shearing during operation. From these results, some failure mechanism theories are proposed to describe the type of failure encountered by each bolt grade, either ductile or brittle depending on the inherent material properties.

Forging and Heat Treating Process Upgrades for a Wrought Railroad Wheel Manufacturing Facility

This paper describes a major capital project that was recently completed at a North American wrought railroad wheel manufacturing facility. The overall goals and concept of the project are outlined. Upgrades and improvements to band saws, the 10,000 ton forging press, rolling mill, and associated hydraulic systems, are described with emphasis on improvements in process speed. Installation of new wheel handling robots, which replaced an additional number of older, less robust wheel handling robots, is reviewed. Further, a new in-line wheel heat treating process, which provides for rim quenching and tempering of the wheel shortly after the forging and rolling process is completed, is described in detail. The new computer-controlled heat treating process features a rotary heating furnace to austenitize the wheels, several rim spray stations for quenching, a slot-in-the roof tempering furnace, controlled cooling operations, and automated Brinell testing. Important equipment maintenance concerns that were addressed are also reviewed. Finite element analysis (FEA) results for the new wheel heat treating process are discussed, along with other process considerations.

Rail Car Tracking Device Selection and Power Consumption

Since its introduction, consumer GPS has made the tracking of critical items in the transportation chain more popular. Shipment of items via rail car is one link in the chain that serves to benefit from GPS technology. This paper discusses a wireless communications system suitable for tracking rail cars. In particular, the power source selection and system testing are described. The system was limited to one device and one power source, a battery. Findings show that the lithium battery selected will power the device for one to three years, depending on transmission activity. Recommended areas of additional research include: battery recharging techniques, effects of connecting sensors to the device, and investigating other communications devices as they become available.

Root Cause Analysis of Passenger Side Door System

This paper presents a real-world application of Root Cause Analysis methods that were applied to analyze and resolve a side door problem that was occurring on a particular fleet of coach cars operated by Amtrak. The foundation of a Root Cause Analysis program is a disciplined engineering process designed to identify physical, human and latent roots of chronic or sporadic problems. This paper presents the engineering challenges encountered while conducting root cause analysis of a complex coach car side doors problem. The coach car side doors system exhibited undesirable characteristics when in service. Mechanical staff received multiple reports that during station stops all of the open side doors would unexpectedly close even though the train speed was at zero. During this unexpected side door closing sequence all of the obstacle detection systems were disabled presenting a potential hazard to the traveling public. The side doors Root Cause Analysis team found the Physical Root cause of failure to be located in the door system software code — a finding that was never suspected following years of trouble with the side doors. As a result of this finding, the door manufacturer corrected the software and issued revised software to be installed fleet-wide. The Human and Latent Root causes were addressed through the development of a standard operating procedure and training for conductors and crew on the proper operation of side doors. The Root Cause Analysis method proved to be a powerful and productive process for achieving a solution to a chronic passenger side door problem.

Real-Time Estimation of Temporal Word Boundaries Without Linguistic Knowledge

A novel real-time algorithm has been developed for estimating temporal word boundaries in measured speech without the need for interpretation of individual words. This algorithm is the foundational building block of a method for estimating a variety of key metrics such as word production rate, phrase production rate, words per phrase, etc., that are indicative of human mental states. In particular, we are interested in developing a system for monitoring locomotive crew alertness. The majority of existing speech processing algorithms relies on pre-recorded speech corpora. The real-time algorithm presented here is unique in that it employs a simple and efficient pattern matching method to identify temporal word boundaries by monitoring threshold crossings in the speech power signal. This algorithm eliminates the need to interpret the speech, and still produces reasonable estimates of word boundaries. The proposed algorithm has been tested with a batch of experimentally recorded speech data and with real time speech data. The results from the testing are outlined in this paper.

Electrical Transients Analysis for Conductor Rail Gaps of Taipei Rapid Transit System

The design for the conductor rail gaps of a rapid transit system complies with service and maintenance criteria for crossovers, pocket track turnouts, walkway side variations, terminal stations, and different power supply sections. The collector shoes of a moving train passing the gaps will produce mechanical abrasion and switching transient characteristics. If the transient voltage is very large, it will produce electrical erosion on the leaving termination of the conductor rail. Maintenance technicians must often replace the damaged components beside the gaps with a new one to maintain service quality, thus, deciding the position and the type of the gaps to reduce arc voltage is very important. This study analyzed transient voltage of Taipei transit train passing crossovers, pocket track turnouts, and the distinct power supply section from deducing electrical circuits. If non-bridgeable gaps are replaced with bridgeable gaps, the bridgeable gaps will produce more arcing current than non-bridgeable gaps for the circuit from transient to steady state. The analysis results indicate that the magnitude of transient voltage depends on the charge and discharge time of the line impedance, the train operation speed and the overlap time of the two collector shoes touching the two sides of the conductor rail.