• Journal of the Korean Society for Precision Engineering
• /
• v.30 no.7
• /
• pp.679-686
• /
• 2013

The reduction unit is one of the most important components in railway cars, due to the transmission of torque from the motor to the wheels. Faulty reduction gears in high-speed trains result from excessive wear on the gear or damage to the gear. These types of gear defects have a significant effect on high-speed rail operation and safety; thus, a diagnosis system for the reduction unit is needed. Vibration diagnosis technology is one of the most effective diagnostics. In this paper, the vibration parameters of a reduction unit were evaluated during a driving-gear test and a full-vehicle test, using kurtosis and the crest factor. These tests were performed under normal operating conditions; a specimen tester was used to diagnose problems in defective gears.

• Journal of the Korean Society for Precision Engineering
• /
• v.30 no.7
• /
• pp.667-672
• /
• 2013

This paper presents the development of a condition monitoring system that monitors the operating conditions of a reduction unit, such as the bearing temperature, gearbox vibration, and gear oil deterioration, and notifies the operator of potential problems or abnormal conditions. A series of field tests on high-speed rail and conventional lines was performed to identify the characteristics of temperature rise and vibration levels on the reduction unit during operation. The monitoring system was designed based on the proper sensor selection, measurement method, and signal analysis to optimize the interface with the operating system of high-speed trains. Application of this monitoring system to high-speed trains will play an important role in their proper maintenance and safe operation.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2005.06a
• /
• pp.383-386
• /
• 2005

An integrated analytical model which should have essential dynamics on the longitudinal railway vehicle is developed. The model consists of translational movement, rotational movement, brake actuator, adhesion force between rail and wheel, and brake friction force between wheel and pad. Thus, during the deceleration for stopping, a feedback controller controlling the brake cylinder pressure is designed to improve ride quality and to release friction problems. Through the developed model, the feasibility of controlling the cylinder pressure is verified for the better performances during braking.

• Proceedings of the KSR Conference
• /
• 2004.06a
• /
• pp.696-701
• /
• 2004

Electric vehicle that is manufactured present by development of electric vehicle technology were available automatic driving. Control of air breaking system for precision stopping is important at automatic driving. Current Electric vehicle is doing precision stopping using braking force control. Braking force control is difficult to take static deceleration by rail condition or change of friction coefficient. Therefore, Proposed the controller in this study is deceleration controller. Designed controller is a robust controller that take state control characteristic for modelling error.

• Proceedings of the KSR Conference
• /
• 1999.05a
• /
• pp.116-123
• /
• 1999

A case of the axle gear box which was one of tile power transmission components of high speed train was supported by the bearings installed in axle and the reaction arm connected in bogie frame. Structural analyses of this case were executed for investigation the application of aluminum for weight reduction. The evaluations of the material strength, the thermal strength and deformation, and the stability of natural vibration were carried out according to computer simulation. It was found out that the steel case was safe from the structural failure. For the aluminum case, there was no worry about the vibration resonance and the static failure, but some efforts to reduce tile deformation of the bearing mounting part.

• Proceedings of the KSR Conference
• /
• 2009.05a
• /
• pp.1191-1197
• /
• 2009

KTX decelerator is a device to fulfil a role of transmission of turning force to reduction device of an axle by serrate device. Currently, KTX decelerator's TBO(Time Between Overhaul) has 3 years cycle. As for the dissembly maintenance of a device, its maintenance is conducted every 1.4M kms. In this study, since opening of KTX, we analyzed reliability, maintainability, availability of KTX decelerator by researching historical records of maintenance of the decelerator, and based on above data, investigated whether its TBO cycle and maintenance works properly or not And we considered maintenance policies of KTX decelerator to improve efficiency in maintenance in the future.

• Proceedings of the KSR Conference
• /
• 1999.11a
• /
• pp.181-188
• /
• 1999

For weight reduction of the gearbox of power bogie of high speed train, aluminum alloy is recommended for the material of the gerabox case. In this paper, three models(Steel G/B Case-Steel BRG. Case[model-S], Aluminum G/B Case-Aluminum BRG. Case[model-A], Aluminum G/B Case-Steel BRG. Case[model-AS]) were compared to each other in the view of thermal expansion. The evaluation of the internal load, thermal expansion deformation and lug analysis were executed. It results that the 'model-A' is excessively deformed and fail in the bolt hole of bearing case. Material change of the bearing case to steel(model-AS) is effective to restrain the deformation of the inner radios of the bearing case and to prevent the failure of that.

• Proceedings of the KSR Conference
• /
• 2008.11b
• /
• pp.584-589
• /
• 2008

A bi-modal tram has been developing to consist of articulated-two cars propelled by CNG hybrid (series type) in Korea since 2003. All wheels are driven by electrical motors independently, which can eliminate differential gears to reduce turning radius and make low floor to provide the old and the handicapped with easy access. In the bi-modal tram, therefore, reduction gear unit is key technology to make low floor and drive wheels independently. This study was aimed at performance evaluations of the reduction gear unit for the bi-modal tram. Oil leakage, oil temperature, vibration, acoustic noise in idle operations were measured for the reduction gear unit of the bimodal tram.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.16 no.12
• /
• pp.8700-8706
• /
• 2015

The first driving device of the power bogies for the Korean high-speed railway vehicle consists of the traction motor (TM) and the motor reduction gears unit (MRU). Although TM and MRU are the mechanically integrated structures, their time between overhauls (TBO) have two separate intervals due to different technical requirements(i.e. TBO of MRU: $1.8{\times}10^6km$, TBO of TM: $2.5{\times}10^6km$). Therefore, to reduce the unnecessary number of preventive maintenances, it is important to evaluate the optimal TBO with a viewpoint of reliability-center maintenance towards cost-effective solution. In this study, derived from the field data in maintenance, fault tree analysis and failure rate of the subsystem considering criticality of the components are evaluated respectively. To minimize the conventional total maintenance cost, the same optimal TBO of the components is derived from genetic algorithm considering target reliability and improvement factor. In this algorithm, a chromosome which comprised of each individual is the minimum preventive maintenance interval. The fitness function of the individual in generation is acquired through the formulation using an inverse number of the total maintenance cost. Whereas the lowest common multiple method produces only a four percent reduction compared to what the existing method did, the optimal TBO of them using genetic algorithm is $2.25{\times}10^6$km, which is reduced to about 14% comparing the conventional method.

• Journal of the Korean Society for Railway
• /
• v.11 no.4
• /
• pp.398-403
• /
• 2008

The propulsion for locomotive application has changed from the DC motor system to the induction motor system. Although the induction motor system has almost reached the stage of maturity, this system also needs to be changed to the PM motor system for the direct drive without using reduction gear. Thus, the IPMSM (Interior buried Permanent Magnet Synchronous Motor) has been adopted to meet the locomotive driving specification. Where the wheel is directly dirven by the traction motor. In this paper, the investigation on IPMSM satisfying driving specifications for the direct drive has been performed using the advanced FEM.