Investigation on Magnetorheological Brake Light Possible Application of for Rail Vehicle

No Thumbnail Available



Journal Title

Journal ISSN

Volume Title


Addis Ababa University


Conventional pneumatic brake systems used in light rail vehicle have several limitations and disadvantages such as the response delay in building up the pressure necessary to actuate the brakes there is also, the long time delay between front and rear car, wear of braking pad and requirement for auxiliary components (e.g. compressor, transfer pipes, auxiliary reservoir and main reservoir) increase the overall weight and it is bulky in size of braking system. This paper presents an electromechanical brake system for light rail vehicle using magnetorheological (MR) fluid. The proposed MR brake consists of rotating disks immersed into an MR fluid and an enclosed electromagnet. When current is applied to the electromagnet coil, the MR fluid solidifies as its yield stress varies as a function of the magnetic field applied by the electromagnet. This controllable yield stress produces shear friction on the rotating disks, generating a retarding braking torque. This type of braking system has the following advantages: faster response, easy implementation of a new controller or existing controllers (e.g. ABS etc.), less maintenance requirements since there is no material wear and lighter overall weight since it does not require the auxiliary components. In this paper practical design criteria such as material selection and MR fluid selection are considered to select a basic MR brake configuration. The mechanical part is modeled using Bingham’s equation, an approach to modeling the magnetic circuit is also proposed in this work. The equation of the torque transmitted by the MR fluid within the brake is derived, based on this equation, after mathematical manipulation, the torque generating by the MRB is investigated theoretically. The MRB in a rail vehicle was studied using a 1/8th vehicle model. Then, a finite element analysis is performed to investigate the resulting structural and heat distribution within the MR brake configuration. Results shows that MRB generates much lower braking torque compared to that of braking torque required for train to stop and a finite element analysis results shows operating temperature can intermittently reach outside the recommended temperature range of the MR fluid, however possible design improvements are suggested to further increase the braking torque capacity and to reduce temperature rise.



Magnetorheological Brake, Brake Light, Rail Vehicle, Investigation