Purpose The purpose of this paper, brake friction material samples with six different contents were produced using three different fiber types consisting of variable proportions of huntite mineral and basalt, glass and steel fibers. The friction properties and formation of the transfer film in these friction materials were investigated. Design/methodology/approach Friction materials were produced using a hot molding method from materials containing 10%–15% huntite in varying proportions, consisting of basalt, glass and steel fibers. The densities and hardness values of the samples were measured. Friction tests were performed using a brake pad friction material tester to determine tribological properties. After the friction tests, microscopic examination of the sample surfaces was performed using scanning electron microscope (SEM) and three-dimensional (3D) surface profilometer devices. Findings Huntite mineral content and fiber type affected the friction coefficient. With an increase in the amount of huntite, the friction coefficient increased in the friction material samples formed with glass and steel fibers. The fiber type and amount of huntite also affected the transfer film formation. The surface roughness values of all the friction materials decreased with an increase in the amount of huntite. The surface roughness values of the samples with glass fibers were higher than those of other samples. Originality/value The importance of using huntite minerals and different fiber types in automotive brake friction materials is emphasized. This will help industrial companies and academics study the tribological properties of friction materials.

Huntite (CaMg3(CO3)4) is a calcium magnesium carbonate mineral and is a mineral in the dolomite group. Although studies on Huntite's flame retardant raw material feature stand out, it is used in the paint industry, and the industrial sectors such as plastics, pol-ymers, special rubbers, and pharmaceuticals. In this study, experiments were carried out by producing brake pad samples in different mixing ratios from huntite mineral and glass fiber, kaolin, graphite, phenolic resin, and rubber powder to be used for brake pads in the automotive industry. Friction coefficient and wear rate which is an important fea-ture for the produced pad samples were measured in the brake pad testing device. Ac-cording to the Archimedes principle, the specific gravity and disc roughness values formed by the brake pad samples on the disc were measured with a roughness tester. According to the measured values, the highest average friction coefficient was obtained in the A45 sample, the minimum wear value was obtained in the A10 sample, and the minimum roughness change was obtained in the A25 sample.

Recently, new brake pads have been developed using sustainable materials that are not harmful to the environment. In this study, the effect of using blue-colored Cupressus arizonica cones was determined as a friction modifier in brake pad composites. Four different samples were prepared by grinding the cone material. The samples’ physical and chemical properties and performances were compared, and finally, their microscopic analyses were visualized by scanning electron microscopy. Maximum friction coefficient and minimum wear rate are required for brake pads. The maximum friction coefficient of 0.39 and the minimum wear rate of the samples containing Cupressus arizonica were obtained in the 0.124X10-7 cm3/Nm BCA3 sample. When the brake pads developed from lignocellulosic biomass were compared, it was determined that the BCA3 sample met the most reasonable performance values.

The gearbox is part of the powertrain that transmits movement from the engine to the wheels. Gears, shafts and auxil-iary systems are used in Gearboxes. By using these systems, it is possible to control the movement of the vehicle at the desired tractive effort and vehicle speed in different gear ratios as well as in different direction situations. To increase vehicle performance, it is necessary to obtain curves close to the ideal traction hyperbola. In this study, vehicle speed and tractive efforts of two different 12-speed vehicles with the same engine characteristics were calculated with Matlab/Simulink. According to obtaining the results, the tractive effort curves based on vehicle speed were estimated and ideal traction hyperbola curves were formed. The comparison of ideal traction hyperboles for both types of gearboxes showed that the curves have a similar structure.

Purpose This study aims to determine the braking performance of limestone as a filler in brake friction materials. Design/methodology/approach Samples containing limestone material (30-35-40%), which can be an alternative to brake friction material filler, were produced. The samples were weighed on precision scales, mixed homogeneously and produced using the hot molding method. The physical and tribological properties of the produced samples were determined, and their microscopic analyzes were made with scanning electron microscopy. Findings As the amount of limestone increased, the density of the samples decreased. The friction coefficient and wear rates were close to each other and within the optimum limits for all samples. Limestone materials can be used instead of barite materials studied in the literature on brake linings. Microcracks were observed only in samples containing 30% and 35% limestone in microscopic images. Originality/value In this study, the wear rate, coefficient of friction and microstructures on the friction surfaces of brake friction materials containing limestone were investigated. The usability of limestone as a filler in brake friction materials provides valuable information to researchers and industrial organizations in the brake friction material field.