• International Journal of Precision Engineering and Manufacturing
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• v.2 no.2
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• pp.31-37
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• 2001

In this paper, a method to improve judder by changing the front and rear wheel brake force distribution ratio was proposed. ADAMS, a commercial dynamic analysis software was used to model a small size bus and its modeling procedure was explained. By using the ADAMS vehicle model, the judder phenomena of the small bus were analyzed, and based on analysis results, the validity of the improvement method was proposed. Also in order to lessen the problem jubber sensitivity analysis and test results were proposed.

• Journal of the korean Society of Automotive Engineers
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• v.6 no.2
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• pp.33-38
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• 1984

Research and development of automotive hydraulic brake hose has been carried out for domestic production. Four different trial products have been developed according to different design factors, and designated as Lot.. 1 through Lot. 4 respectively. Eleven kinds of static and dynamic performance tests have been conducted on each sample product of Lot. number, and the trial product by the Lot. 2 design factors was found to meet all the test specifications. Therefore, the automotive hydraulic brake hose could be localized in Korea.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.615-620
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• 2010

During braking of railway vehicles the repetitive thermal shock leads to thermal cracks on disc surface, and the lifetime of brake disc is dependent on the number of trimming works for removing these thermal cracks. Many tries for development of high heat resistant brake disc to extend the disc life and to warrant reliable braking performance has been continued. In present study, we carry out the computational fatigue analysis for thermal fatigue test in three candidate materials which were made to develop new high heat resistant material. Using FEM, we simulate thermal fatigue test in three candidate materials and conventional disc material. We then estimate the number of cycle to thermal crack initiation based on data from mechanical fatigue tests, and the results are compared with each material. For each material, the correction factor for $N_{f-40}$ which is the number of cycles when crack over $40{\mu}m$ was observed in thermal fatigue test is decided. From this study, we can verify the performance of thermal fatigue test system and suggest a qualitatively comparative method for heat resistance by FEM analysis of thermal shocking phenomenon.

• Tribology and Lubricants
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• v.36 no.2
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• pp.88-95
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• 2020

In this study, we investigate the mechanical properties of high manganese steel, and the friction and wear characteristics of brake friction material containing this steel, for passenger car application, with the aim of replacing copper and copper alloys whose usage is expected to be restricted in the future. These steels are prepared using a vacuum induction melting furnace to produce binary and ternary alloys. The hardness and tensile strength of the high manganese steel decrease and the elongation increases with increase in manganese content. This material exhibits high values of hardness, tensile strength, and elongation; these properties are similar to those of 7-3 brass used in conventional friction materials. We fabricate high manganese steel fibers to prepare test pad specimens, and evaluate the friction and wear characteristics by simulating various braking conditions using a 1/5 scale dynamometer. The brake pad material is found to have excellent friction stability in comparison with conventional friction materials that use 7-3 brass fibers; particularly, the friction stability at high temperature is significantly improved. Additionally, we evaluate the wear using a wear test method that simulates the braking conditions in Europe. It is found that the amount of wear of the brake pad is the same as that in the case of the conventional friction material, and that the amount of wear of the cast iron disc is reduced by approximately 10. The high manganese steel is expected to be useful in the development of eco-friendly, copper-free friction material.

• Proceedings of the KSR Conference
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• 2003.10c
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• pp.363-368
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• 2003

The Inter-laboratory comparison test which is demanded on the authorized test of ISO 17025 is the program to guarantee the reliability for test results of test organization. In order to apply to the field of railway, brake disk lining as one of the railway components has been selected and the comparison test is executed for the purpose of guaranteeing the reciprocal reliability for the test result of both organizations and enlarging the substantial technique exchange of both nations by the standard establishment with test procedures and test programs from now on.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2004.11a
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• pp.47-52
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• 2004

The purpose of this study is to investigate the friction characteristics of brake pads according to different ratios of $BaSO_4/CaCO_3$. Four brake pads with different ratios of $BaSO_4/CaCO_3$ were manufactured. The friction characteristics of brake pads were tested using 1/5 reduced scale tester. With increasing of the amount of $BaSO_4$ density and shear strength of brake pads were increased and hardness of brake pads were decreased. In effectiveness, the friction coefficient of brake pad was higher and the stability of friction coefficient was better as the ratio of $BaSO_4$ increased. In fade test, friction coefficient of B3 sample used only $CaCO_3$ was decreased rapidly. B1 sample showed a good noise performance without noise generation. The wear resistance of samples were decreased with increasing of the ratio of $CaCO_3$.

• Proceedings of the KSR Conference
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• 2009.05a
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• pp.1624-1633
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• 2009

Brake system in railway train operates to reduce the speed of the train or to stop the train via changing the kinematic energy into heat energy for emission and so brake system makes an important rule to transport passenger and cargo for safety operation. Recently operators have a matter of grave concern for the verification of performance in brake system. To verify the exact performance of brake system, most of brake test has been carried out on real operating track condition. Therefore we will determine the braked weight of indirect brake system applied in Iran DMU(Diesel Multiple Unit) in accordance with mc leaflet 544-1, which is to enable Iran DMU to achieve the required braking distances in defined situation.

• Tribology and Lubricants
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• v.30 no.4
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• pp.240-245
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• 2014

Low alloy heat resistant brake disk and sintered brake pad are applied to mechanical brake system for the speed-up of urban rapid transit. In this research, we analyzed how the frictional characteristics between brake disk and pad are influenced by the disk mass. At a high disk mass, the friction stability was the lower value as a result of the lack of tribofilm formation at the disk surface. Wear rates of friction materials showed the higher value at a low disk mass and wear rates of 10 mm and 15 mm showed the similar level. Average friction coefficient was the lower value at the 10 mm disk thickness and range of variation of average friction coefficient was also the smaller value at the 10 mm disk thickness. However, there were no significant changes in the friction coefficients under any of test conditions. Surface roughness of a disk showed the highest value at the 5 mm disk and surface roughnesses of 10 mm and 15 mm showed the similar level. As a result, friction characteristics of disk mass influenced the friction stability, as well as the wear rate of friction pad and disk, but not the friction coefficient.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.10b
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• pp.429-430
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• 2002

In this study, three kinds of brake: discs including two coated brake discs and one steel disc were tested under the same experimental conditions on a reduced scale braking test bench. Plasma spray coating technique was used to coat ceramic powder on the discs. In the test, four commercial sintered brake pads were coupled with discs. Ceramic coated discs have shown good stability in friction coefficient at high speed and high energy braking conditions. However, ceramic coated discs caused more wear loss of pad mass than the steel disc. It was shown that thermal barrier effect in ceramic coated discs adjusted the thermal partition between pad and disc. Steel disc showed fluctuating friction coefficient at high speed but less wear loss of pad mass than ceramic coated discs.

• Transactions of the Korean Society of Automotive Engineers
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• v.13 no.6
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• pp.142-153
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• 2005

The brake judder is a phenomenon that the steering wheel is abnormally vibrating when the car is braked at a high speed. It is classified by the cold and the hot judder. The former is generated due to the initial uneven disk surface and the latter is resulted from the uneven heat spots on disc surface by repeatedly braking. There are two ways to reduce the judder. One is to control vibration by modification of the disk shapes and pad ingredients. The other is to improve modal characteristics of the suspension system. The latter approach is used in this research. In this paper, the real vehicle test and computer simulation are considered to systematically understand the judder phenomenon of the vehicle. The Macpherson strut suspension is employed. Especially, the judder sensitivity is calculated based on design sensitivity analysis. A bush stiffness was reworked and braking test was done to verify the sensitivity result. The judder reduction by the mode control was verified.