Trailer Car Research Articles

Estimation of the damping effects of suspension systems on railway vehicles using wedge tests

The damping ratios of suspension systems on a railway vehicle were estimated in terms of the free-decay responses obtained by applying the logarithmic-decrement method to data obtained in wedge tests. The characteristics of the free-decay responses were measured both for motor and trailer cars experiencing either the tare loading (AW0) or crush loading (AW3) condition and either inflated or deflated air springs. The considered cases included bouncing, pitching, rolling and lateral motions. A dynamic model was established and the simulation results were compared with the experimental results. For the vertical cases, the time cycles and displacement amplitudes of the free-decay response are related to the state of the air springs and the vehicle load. The damping ratio of the secondary suspension for inflated air springs is about three to five times higher than for when the air springs are deflated. For the primary suspension, it is two to four times higher. Also the heavier the carbody loads, the much more severe is the divergence. Furthermore, the damping ratios have their largest values for the pitching modes, followed by the bouncing modes and finally the rolling modes. For the lateral cases, the free-decay responses have similar characteristics to those of the vertical responses but with smaller amplitudes. All the tests show good agreement with one another, and the primary and secondary suspensions show similar regularities. The simulations show a good agreement with the test results and highlight that the initial velocity has only a limited effect on the test results.

Calculation and laboratory testing of the rotation resistance of a bogie

The rotation movement between bogie and carbody is studied using vehicle system dynamics theory and formulas for the rotation resistance factor are derived for different air spring states. Laboratory tests are conducted and the obtained results are compared with calculations. The rotation resistance factor for motor and trailer cars experiencing AW0 and AW4 loading conditions when air springs are in inflated, deflated and over-inflated states are considered so as to validate the proposed formulas and test and discuss error sources. The rotation resistance factor of the bogie is related to the rotation angle and speed. The faster the rotation speed, then the greater is the rotation resistance factor. The greater the rotation angle, then the greater is the rotation resistance factor. The maximum rotation resistance factor is 0.094 for a trailer car at a rotation speed of 1 deg/s and experiencing AW0 loading conditions and with the air springs in the deflated state. The maximum rotation resistance factor when the air springs are deflated is much greater than that when the air springs are in the inflated state for a rotation speed of 1 deg/s. The maximum rotation resistance factor obtained at a rotation speed of 1 deg/s is much greater than the one obtained at 0.2 deg/s. The over-inflated state of air springs has little influence on the rotation resistance of the bogie. The calculated results obtained when considering air springs in inflated and over-inflated states are slightly smaller than test results with a maximum difference of 0.02. For the deflated state of the air springs, the calculated and test results for a trailer car are equivalent and the calculated results are slightly larger than the test results for a motor car with a maximum difference of about 0.02. The theoretical formulas should consider the dynamic nature of stiffness properties and damping effect of air springs. The effects of other suspension components should also be considered. A laboratory test or field test after assembly is an essential requirement. The comparison of test and calculated results validates the proposed formulas and allows sources of error to be discussed.

On minimizing derailment risks and consequences for passenger trains at higher speeds

The first part of this article deals with the possibility of preventing wheel climbing derailments after an axle journal failure by implementing mechanical restrictions between the wheelsets and the bogie. A multi-body system (MBS) computer model is developed to account for such an axle failure condition, which is successfully validated by comparing the pre-derailment sequence of events with two authentic cases. An extensive parameter analysis on the maximum vertical and longitudinal play between the wheelset and the bogie, required to prevent a high-speed power or trailer car to derail, is performed for various combinations of running conditions in curves. Once an actual derailment has occurred on conventional passenger trains at 200 km/h, extensive MBS simulations are performed on the feasibility of utilizing alternative substitute guidance mechanisms, such as low-reaching parts of bogie frame, axle box, or brake disc, as means of minimizing the lateral deviation. Results are presented in terms of geometrical parameters that lead to a successful engagement with the rail for a total of 12 different derailment scenarios. These are caused by an axle journal failure, an impact with a small object on the track, or a high rail failure. Minimizing the lateral deviation is also investigated by means of restraining the maximum coupler yaw angle and altering the bogie yaw stiffness. Time-domain simulations are also performed in terms of lateral track forces and derailment ratio when negotiating a tight horizontal ‘ S-curve’. Further, the articulated train concept is investigated in terms of the post-derailment vehicle behaviour after derailments on tangent and curved track at a speed of 200 km/h. In this respect, a trainset consisting of one power car and four articulated passenger trailer cars is modelled in the MBS software. Results in terms of lateral deviation and maximum carbody roll angle are presented as a function of different inter-carbody damper characteristics and running gear features. The feasibility of these damper characteristics is also tested in terms of lateral track forces and derailment ratio when negotiating a tight horizontal S-curve.

The effect of rubber contact on the fretting fatigue strength of railway wheel tire

The cause of the ICE train derailment, which occurred in 1998 at Eschede, was fatigue failure originating on the inside of the wheel tire. Rubber-sprung resilient wheels were used for the trailer cars. The wheel tire is mounted on the wheel disc. Thirty-four rubber pads were arranged between the wheel disc and the wheel tire. It was postulated that fretting fatigue between the rubber block and the inner side of the tire might have an influence on the initiation of the incipient crack. In order to clarify the influence of the rubber contact on the fatigue strength of the tire, fretting fatigue experiments under rubber contact conditions were performed. During the fundamental fretting fatigue test using bridge pads and small size carbon steel specimens, no typical fretting damage such as fretting wear and minute cracks were observed due to contact of the rubber. Stress conditions of the rubber-sprung wheel under vertical and lateral wheel loads were evaluated by a three-dimensional elastic stress analysis. Since the rubber is a super-elastic material, the Mooney–Rivlin model was used in the FEM calculation. It was found that the wheel tire is subjected to a cyclic stress during one revolution of the wheel and the maximum stress occurred at the center of the inner surface of the tire where the fatigue crack initiated. Fatigue strength of the wheel tire was determined by the rotating bending fatigue testing of specimens taken from the tire. It was found that the tire with an 862 mm diameter at a wheel load of 80 kN had a safety factor more than 3.5 from a fatigue limit diagram with a failure probability of 0.01. To confirm the fretting damage under the rubber contact and the result of the fatigue strength evaluation, fatigue tests of a full size wheel were made. After 20 million cycles at the wheel load of 280 kN, which was just below the endurance limit estimated by the endurance limit diagram, no fretting damage and no fatigue cracks were observed. The wheel was, however, fractured at 1.56 million cycles under the maximum load of 308 kN, which was just above the endurance limit. The estimation of the safety factor of 3.5 estimated from the endurance diagram was confirmed by the full size fatigue testing. It was concluded that there was no effect of fretting due to the rubber contact on the fatigue strength of the rubber-sprung single-ring railway wheel.

Analysis theory of spatial vibration of high-speed train and slab track system

The motor and trailer cars of a high-speed train were modeled as a multi-rigid body system with two suspensions. According to structural characteristic of a slab track, a new spatial vibration model of track segment element of the slab track was put forward. The spatial vibration equation set of the high-speed train and slab track system was then established on the basis of the principle of total potential energy with stationary value in elastic system dynamics and the rule of “set-in-right-position” for formulating system matrices. The equation set was solved by the Wilson-ϑ direct integration method. The contents mentioned above constitute the analysis theory of spatial vibration of high-speed train and slab track system. The theory was then verified by the high-speed running experiment carried out on the slab track in the Qinghuangdao-Shenyang passenger transport line. The results show that the calculated results agree well with the measured results, such as the calculated lateral and vertical rail displacements are 0.82 mm and 0.9 mm and the measured ones 0.75 mm and 0.93 mm, respectively; the calculated lateral and vertical wheel-rail forces are 8.9 kN and 102.3 kN and the measured ones 8.6 kN and 80.2 kN, respectively. The interpolation method, that is, the lateral finite strip and slab segment element, for slab deformation proposed is of simplification and applicability compared with the traditional plate element method. All of these demonstrate the reliability of the theory proposed.

Post-derailment dynamic simulation of rail vehicles – methodology and applications

An earlier developed multi-body system post-derailment module, that predicts the wheelsets’ behaviour after impact with concrete sleepers, is upgraded to account for possible wheel–rail fastener impact situations, after train derailments at high speed. The vertical stiffness describing the wheel–fastener impact behaviour is calibrated and validated based on two authentic derailment cases. Geometrical specifications that permit a brake disc and a bogie frame to act as substitute guidance mechanisms after flange climbing derailments on curved track are presented for an X 2000 trailer car. Further, an introductory analysis on the post-derailment vehicle behaviour on tangent track after a ‘flange on rail head’ derailment condition is also presented as a function of bogie yaw resistance. The risk of carbody overturning after derailments on tangent track is assessed as a function of coupler height and carbody centre of gravity as well as bogie transversal beam position.

추진장치 성능측정 시스템에 관한 연구

한국형 고속철도차량(350km/h)은 7량 1편성으로 구성되어 있으며, 현재 오송기지에서 본선시운전 시험운행중에 있다. 이 차량에 취부된 여러 장치들의 성능을 확인하기 위해서 다양한 신호를 측정하기 위한 측정시스템이 구축되었다. 이 논문에서는 한국형 고속철도차량의 추진장치 성능측정 시스템에 대하여 서술하였다. 추진장치의 성능측정은 Motor Block의 성능확인에 초점을 맞추고 측정할 위치를 정하였다. 본선시운전 시험을 위해, 철도연에서 자체적으로 상시계측시스템을 개발하였으며, 이 시스템을 통해 추진시스템의 각종 전기신호를 입력받아 분석을 실시하였다. 이를 통해서 개발된 추진시스템의 성능을 확인할 수 있었다. The korean high speed train(350km/h), composed of 7cars that are 2 power cars, 2 motorized car and 3 trailer cars, has been developed and is under on-line test. To verify the design requirements about the functions and traction performances of this train, KRRI(Korea Railroad Research Institute) decided to evaluate traction performances of the train during on-line test. For this purpose, such as torque, velocity, voltage and current, must be measured. KRRI has developed the measurement system that can be measured vast and various signals effectively. In this paper, we introduce traction performances of korean high speed train. The traction measurement items are focused on the verification of motor block performances. Motor block are consist of 2 motor. For this test, we verified traction performances of korean high speed train.

한국형 고속전철 차량소음 예측 및 부품 소음관리방안

KITECH and ODS performed a study of internal and external noise prediction of the Korean high speed prototype test train(HSR 350X). The object of this study was 3 kinds of cars, trailer car(TT2), motorized car(TMI ) and power car(TPI) and the predicted noise was for the two different driving speeds in free field and tunnel conditions. Data of carbody design and noise sources were delivered from manufactures. Some of noise sources which were not available in the project team, were chosen by experiences of ODS. Internal noise level of each car was predicted for two cases i.e, at 300 km/h and 350 km/h. In addition sound transmission path and dominant noise sources were also investigated for each section of the car, which is circular shell typed part of whole carbody. In case of TT2, the dominating sound transmission path is the (floor in terms of structure-borne noise and air-borne noise. The main noise sources are structure-borne noise from the yaw-damper and air-borne noise from the wheel/rail contact, whereas the dominating sound transmission path of TMI are floor and sidewall below the window in terms of structure-borne noise. The main noise sources of TMI are structure-borne noise from motor/gear unit and the yaw-damper in the free field, and air-borne noise from the wheel/rail contact and structure-borne noise from motor/gear unit in the tunnel. Through the external noise prediction for the KHST test train formation, the noise form the wheel/rail contact is estimated as one of the major sources. In addition, the noise specification of sub-component was proposed for managing each sub-surpplier to reach the KHST noise requirement. The specification provide the sound power of machinery part and transmission loss of component of carbody structure. The predicted noise level in each case exceeded the required limit. Through this study, the noise characteristics of the test train were investigated by simulation, and then the actual test will be performed in near future. Both measured and calculated data will be compared and further work for noise reduction will be continued.

Implementing Train Applications Based on the Distributed Shared Memory Paradigm

A high speed trainset consists of a power car (or power cars) and trailer cars. Each car has its own processor which communicates via a network in the train. For dependability, most of data (objects) in memory are replicated on each processor. To design applications in the context of distributed systems, a simple and portable method consists in utilizing the Distributed Shared Memory (for short DSM) paradigm. On a group of Sun Workstations, an evaluation model has been implemented consisting in a set of hierarchical software layers to offer a DSM with two consistency criteria, namely sequential consistency and causal consistency. On top of this DSM, the application layer implements a typical train application software namely door management. In this train application software, focus was put on portability, dependability and safety issues.

Stabilization of Passenger Car-Caravan Combination Using Four Wheel Steering Control

SUMMARY This study aims to stabilize the trailer at high speed. The behavior of passenger cars with four wheel steering system, vehicles with rear wheel steering and of trailer and passenger car are similar. This is regarded as an optimal regulator problem with linear equation of motion, and a state variables feedback control system is adopted. The problem of stability at high speed on a straight course can be solved. Therefore, the passenger car-trailer system can be stabilized. Furthermore, this study indicates the way forward to stabilize a passenger car-trailer system.

Lackawanna Suburban Electrification

The initial electrification on the Delaware, Lackawanna & Western Railroad includes approximately 68 route miles and 158 track miles of line out of Hoboken, New Jersey, and covers the more important parts of the suburban service and a small amount of freight transfer switching. The 3,000-volt d-c. system is used. Power is purchased in the form of three-phase, 60-cycle, high-tension, alternating current delivered by the power companies to five substations owned and operated by the railroad located along the right-of-way. Four of the substations are manually operated and one is fully automatic. Mercury-arc rectifiers are used exclusively for converting the alternating current to 3,000-volt direct current. The rectifiers have excited grids and are compounded to give substantially flat voltage up to 150 per cent load. All d-c. distribution is through the catenary system, auxiliary feeders not being necessary. All d-c. circuits are protected by high-speed magnetic blow-out circuit breakers. The catenary system is of the tangent-chord double-contact wire type supported on steel structures in multi-track sections and on creosoted wood poles on the single track branch. Multiple-unit trains are used exclusively in the passenger service, made up of two-car units consisting of a motor car and a trailer car, semi-permanently coupled together. Motors are insulated for 3,000 volts, are operated in series-parallel under electropneumatic control with automatic acceleration, and are self ventilated. The freight transfer service is handled by two locomotives of the ``three power'' type, arranged for operation from the 3,000-volt d-c.