• Tribology and Lubricants
• /
• v.22 no.2
• /
• pp.87-92
• /
• 2006

In tread brake of freight cars, brake force is produced by the friction between the wheel and the brake shoe. Friction coefficients associated with the brake power, weight variation and brake shoe types should be sensitively treated as the design parameters. The conditions of the car, empty and loaded, should also be taken into consideration in brake force design and the control of brake force has some limitations in terms of the brake system design so that the brake friction materials selection should be considered as important measures to solve that difficulties. Friction characteristics of brake friction materials should remain within the range of maximum and minimum value and the friction performance should remain stable regardless of brake time and temperature. This study presented an experimental evaluation method to secure optimum brake performance by keeping safe brake effect and brake distance by the friction coefficient of the brake shoe of the freight cars.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2005.05a
• /
• pp.861-864
• /
• 2005

Brake noise has been one of the most difficult concerns in the automotive industry. Although substantial research has been conducted to predict and eliminate brake noise, there is yet no method to completely suppress brake noise. Furthermore, little effort has been made to improve noise and vibration characteristics of the railway brake system. The amount of sound energy radiated from the railway brake system is much larger than that from the automobile, and it causes discomfort of passengers in the station. In this paper, noise and vibration caused by the braking force of the KTX vehicle have been measured and analysed. Results show that noise level increases abruptly right before a train comes to a complete stop. Furthermore, typical characteristics of the disk brake squeal have been observed.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.25 no.12
• /
• pp.1739-1747
• /
• 2001

Experimental study has been conducted to clarify the pneumatic characteristics of brake system for freight train and enhance the performance of diaphragm valve. Empty-load and diaphragm valves are installed in pneumatic brake system for freight trains of KNR (Korean National Railroad). Experiments are conducted by using freight train and diesel locomotive in operation. From the experimental results. new quick release valve shortens release time after brake application. In case of normal brake application, the release time is shortened to 34% of the original diaphragm valve. Reducing the release time of pneumatic brake system will be helpful to assure brake-release application and save maintenance efforts like wheel grinding.

• Journal of the korean Society of Automotive Engineers
• /
• v.8 no.4
• /
• pp.56-65
• /
• 1986

This paper theoretically analyzed the relations between the out-put braking torque and the wheel cylinder pressure in the leading-trailing drum brake for heavy duty truck as the characteristics of friction in break lining, comparing with the results derived from full-scale inertial brake dynamometer test in actual braking condition to develop reliable brake system in extensive using conditions. The main results obtained are as follows; 1) The characteristic curve representing the relations between BEF (Brake Effectiveness Factor) and Friction coefficient derived from theoretical analysis are consistent with the experimental results of dynamometer test. 2) According to the results of dynamometer test, the friction coefficient of brake lining is subject to initial brake speed and the actual using temperature in brake system.

• Journal of Auto-vehicle Safety Association
• /
• v.7 no.3
• /
• pp.19-24
• /
• 2015

Brake pads are a component of disc brake system of automobile and consist of steel backing plates and friction material facing the disk brake rotor. Due to the repeated sliding forces and torque in vehicle braking, friction performance of brake pads are ensured. Futhermore, the brake pad is one of major tuning components in aftermarket, mechanical characteristics of the brake pad are necessary to evaluate for establishing the certification standards of tuning components. This study had performed the five specimen tests for friction coefficients and wear loss rates according to the SAE test specification. Using the instrumented indentation method, yield strength and tensile strength were measured. Friction coefficients, 0.386 - 0.489, and wear loss rates, 1.0% - 3.7% are obtained. The range of yield strength and tensile strength are 21.4 MPa - 105.3 MPa and 39.5 MPa - 176.4 MPa respectively.

• Tribology and Lubricants
• /
• v.27 no.2
• /
• pp.95-100
• /
• 2011

The brake disc materials for railway vehicle have been mainly used cast-iron. The brake disc and pad should be light, resist to a thermal crack and absorb enough friction energy. In order to satisfy this requirement, aluminum alloy brake disc for railway vehicle has been newly developed. The aluminum itself has not been considered the friction material for railway vehicle. However, in the case of aluminum composite with dispersed ceramic particles, friction characteristics, resistance to wear and heat are much improved. In the present study, aluminum composite brake disc of 20% ceramic particle and three kinds of organic pads have been tested in dynamometer. The results show that Al MMC brake disc and pad have good friction coefficient and wear rate, and thermal cracks in brake disc have not been initiated. Also, the Al MMC brake disc can be applied to railway vehicle of 150 km/h.

• Tribology and Lubricants
• /
• v.29 no.3
• /
• pp.171-179
• /
• 2013

In this study, hydraulic systems of the rope brake system of an elevator are modeled to evaluate design parameters that consider friction characteristics such as cylinder pressure, piston displacement, and flow rate. Hydraulic systems of the rope brake system are analyzed using the commercial program AMESim. Analysis modeling data are compared with data obtained from experiments, and the analysis modeling results are found to be reliable. The analysis results will be used to design hydraulic systems of the rope brake system of elevators.

• Proceedings of the KSR Conference
• /
• 1999.05a
• /
• pp.110-115
• /
• 1999

Experimental study is conducted to clarify the pneumatic characteristics of brake system for freight car. KNR(Korean National Railroad)'s freight cars have the laden-tare type control valve of brake system. But, laden-tare type control valve has some shortcomings to match the high speed freight car. Newly developed diaphragm type control valve is introduced to adopt freight car for speed-up. The test using the formated train set consisted of 21 cars is conducted to estimate the pneumatic braking efficiency of the mixed train set. From the results of experiment, the pressure characteristics of each brake cylinder show similar patterns qualitatively. But, in the case of release and brake application, quantitative pressure values of brake cylinder are different.

• Proceedings of the KIEE Conference
• /
• 2003.11c
• /
• pp.616-620
• /
• 2003

Brake action is important in train operation. In case of diesel motor cas, coachs and wagon, the brake system is only act on the stop of train, but it is emphasis on safety and convenience in urban transit system such as EMU, subwar, AGT, etc. Brake of EMU has two types. one is called service brake that is used at normal operation. The other is called emergency brake. it is used at emergency operation. Service brake bring a EMU to a halt through a blending brake that form electronic brake and frictional brake. Generally EMU compose motor car and trailer car. Blending brake bring a EMU to a halt through a blending brake that form electronic brake of motor car and frictional brake of trailer car. Blending braking technology have different characteristics each nations or manufacturing companies. but deceleration command that is parameter decide blending brake. According to deceleration command, electronic brake and frictional brake are applied differently So braking power is different. electronic brake and frictional brake must be used appropriately as deceleration command. Also braking facilities must be stopped EMU more economically and safely through revision of algorism about blending brake according to output diagram. Thus The purpose of paper is to propose blending braking control way as consideration of braking output diagram used deceleration command that influence blending brake of EMU.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.9 no.4
• /
• pp.148-156
• /
• 2001

Brake judder, one of low Sequency vibrations in brake system is determined by the excitation of Brake Torque Variation (BTV). The largest contributor to BTV is disc thickness variation. In this study, the static loads of brake torque at Suspension Mounting Points (SW) are obtained by the quasi-static analysis using DADS. The dynamic loads with frequency of BTV at SW are derived from correlation between forced vibration analysis with static loads and brake test results. And the accelerations at steering wheel were analyzed by forced vibration analysis with dynamic loads using commercial finite element program MSC/NASTRAN so that vibration characteristics of vehicle due to brake judder were investigated. Reliability of analysis results was verified through comparing the brake test results. Also, a parametric study with natural frequencies of frame, such as the 1st torsional mode and 1st bending mode, was conducted to reduce vibration amplitudes. As a result we could detect frame natural frequency conditions to improve vibration characteristics and obtained the frame model to reduce vibration amplitude.