Measurement of wheel–rail contact forces is very important, but it is not executed so often because of its difficulties. A new measuring method introduced in this paper can measure such contact ...forces without special wheelsets equipped with strain gauges and slip rings or telemeters. In this method the lateral contact force is measured from the lateral distortion of wheel measured directly by several non-contact gap sensors. Normal and longitudinal contact forces are also measured from the deflection of spring or the strain of parts of the bogies except wheelsets. According to the results of full-size bogie stand tests and train running tests, it is verified that the new method has sufficient practicability of monitoring the contact forces on commercial lines.
The derailment coefficient, which is calculated based on the wheel-rail contact forces, indicates the running safety of a railway vehicle with respect to flange climb derailment. The value of the ...derailment coefficient changes constantly due to numerous factors associated with the vehicle and track conditions while the vehicle runs on a service line. Therefore, it is desirable to monitor the state of the wheel/rail contact in order to ensure the running safety. Recently, a new monitoring bogie, which can measure the derailment coefficient during commercial operations, has been developed and introduced into some service lines. Large-scale data have been collected by this monitoring bogie. In this paper, the temporal subtraction analysis is carried out for preparing appropriate plan for reducing the derailment coefficient based on these data. In the analysis, the vehicle running position is important for accurate calculation of the difference between two waveforms. However, the vehicle running position contains errors because of the accumulated error of integral calculation of the vehicle velocity. The present paper proposes a method which modifies the running position along track so that the two waveforms are well matched. The proposed method is based on DP matching, and the waveforms of the track irregularity of twist estimated by the monitoring bogie are used in the method. After DP matching, an example of temporal subtraction analysis of the derailment coefficient between two periods is performed. Finally, by using the long-term measurements acquired by the monitoring bogie, the monthly variation of the derailment coefficient for a certain spot on the track is shown as a practical example.
To estimate the safety against flange-climb derailments the safety measures based on Nadal's formula have been used in the world. These measures are effective, but the safety margin against ...flange-climb cannot be estimated quantitively because the actual friction condition between rail and wheel flange cannot be measured by conventional methods. In this paper, the authors propose a new method for the estimation of the friction condition between rail and wheel flange, and using the estimated value of the friction coefficients, a safety measure, the “flange-climb index” (FCI), is proposed. The value of FCI can evaluate the margin for the safety against flange-climb occurrences quantitatively according to the friction conditions.
•Y/Q in Nadal's formula cannot examine the margin against flange-climb occurrence quantitatively.•The authors propose a new safety measure index FCI against flange-climb derailments.•FCI can quantitatively estimate the margin against flange-climb occurrences.•FCI is calculated considering the friction coefficient between wheel flange and rail.•The friction coefficient can be estimated by look-up tables created by MBD simulations.
Controlling the friction between wheel and rail is direct and very effective measures to improve the curiving performances of railway trucks, because the curving performances depend much on friction ...characteristics Authors have proposed a method, “fnction control”, which utilizes friction modifier (KELTRACK™ HPF) with onboard spraying system With the method, not only friction coefficient, but also fuction characteristics can be controlled as expected In this study, MBD simulation is very valuable tool to foresee the effect of the control in advance of experiment with real car And the creep characteristics of wheel/rail contact with the fuction modifier takes very important role in the simulation In this paper, authors propose a theoretical model of wheel/rail contact condition considering the creep characterstics of friction modifier, which is derived the application of principle tribological theories
The derailment coefficient, which is calculated based on the wheel-rail contact forces, indicates the running safety of a railway vehicle with respect to flange climb derailment. The value of the ...derailment coefficient changes constantly due to numerous factors associated with the vehicle and track conditions while the vehicle runs on a service line. Therefore, it is desirable to monitor the state of the wheel/rail contact in order to ensure the running safety. Recently, a new monitoring bogie, which can measure the derailment coefficient during commercial operations, has been developed and introduced into some service lines. Large-scale data have been collected by this monitoring bogie. In this paper, the temporal subtraction analysis is carried out for preparing appropriate plan for reducing the derailment coefficient based on these data. In the analysis, the vehicle running position is important for accurate calculation of the difference between two waveforms. However, the vehicle running position contains errors because of the accumulated error of integral calculation of the vehicle velocity. The present paper proposes a method which modifies the running position along track so that the two waveforms are well matched. The proposed method is based on DP matching, and the waveforms of the track irregularity of twist estimated by the monitoring bogie are used in the method. After DP matching, an example of temporal subtraction analysis of the derailment coefficient between two periods is performed. Finally, by using the long-term measurements acquired by the monitoring bogie, the monthly variation of the derailment coefficient for a certain spot on the track is shown as a practical example.
Controlling the friction between wheel and rail is direct and very effective measures to improve the curving performances of railway trucks, because the curving performances depend much on friction ...characteristics. Authors have proposed a method, 'friction control', which utilizes friction modifier ($KELTRACK^{TM}$ HPF) with onboard spraying system. With the method, not only friction coefficient, but also friction characteristics can be controlled as expected. In this study, MBD simulation is very valuable tool to foresee the effect of the control in advance of experiment with real car. And the creep characteristics of wheel/rail contact with the friction modifier takes very important role in the simulation. In this paper, authors propose a theoretical model of wheel/rail contact condition considering the creep characteristics of friction modifier, which is derived the application of principle tribological theories.
Development of onboard friction control Suda, Yoshihiro; Iwasa, Takashi; Komine, Hisanao ...
Wear,
03/2005, Letnik:
258, Številka:
7
Journal Article, Conference Proceeding
Recenzirano
Onboard friction control system has been developed for vehicles of Tokyo Subway (TRTA). In subway lines, there are many tight curves that may cause squeal noise, excessive wear of rail and also rail ...corrugation. To solve these various problems, onboard friction control system has been developed and has been equipped to commercial trains. The effect of friction control has been confirmed by the field running test with measuring wheelset. After that, under the service running condition of the equipped trains, the long-term observation proved the effect of the friction control by reducing L/V value (the ratio of lateral (L) and vertical (V) force between wheel and rail), lateral acceleration of inner rail and also sound level beside rail.
A Method to Apply Friction Modifier in Railway System MATSUMOTO, Kosuke; SUDA, Yoshihiro; IWASA, Takashi ...
JSME International Journal Series C Mechanical Systems, Machine Elements and Manufacturing,
06/2004, Letnik:
47, Številka:
2
Journal Article
Recenzirano
Odprti dostop
Controlling the friction between wheel and rail is direct and very effective measures to improve the curving performances of bogie trucks, because the curving performances of bogie truck depend much ...on friction characteristics. Authors have proposed a method, “friction control”, which utilizes friction modifier (KELTRACKTM HPF) with onboard spraying system. With the method, not only friction coefficient, but also friction characteristics are able to be controlled as expected. In this paper, results of fundamental experiments are reported which play an important role to realize the new method.
A new concept of improving car behavior in curving by the control of creep force with friction modifier was proposed by the authors. The fundamental experiments were performed by two-roller-rig ...testing machine to evaluate the creep force characteristics between wheel and rail with or without friction modifier. The other hand, on-board spraying system for friction modifier had been developed by authors and equipped on the service car. And the test results in service line show that the effect of installing the friction modifier into railway system has improved the curving performance. This paper presents results of experiments with scaled model vehicle and theoretical analysis of improved curving performance by the proposed method with friction modifier between wheel and rail with scaled model vehicle.
Controlling the friction between wheel and rail is direct and very effective measures to improve the curving performances of railway trucks, because the curving performances of truck depend much on ...friction characteristics. Authors have proposed a method, “friction control”, which utilizes friction modifier (KELTRACKTM HPF) with onboard spraying system. With the method, not only friction coefficient, but also friction characteristics are able to he controlled as expected. In this paper, results of fundamental experiments are reported which play an important role to realize the new method.
PDF
