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Tribology in the Automotive Sector
Published in Jitendra Kumar Katiyar, Alessandro Ruggiero, T.V.V.L.N. Rao, J. Paulo Davim, Industrial Tribology, 2023
Sudheer Reddy Beyanagari, P. Kumaravelu, Dhiraj Kumar Reddy Gongati, Yashwanth Maddini, S. Arulvel, Jayakrishna Kandasamy
Brakes are the devices used to slow down or stop a vehicle. Braking is required to reverse the vehicle’s acceleration and lead it rearward. During the braking operation, the vehicle’s kinetic energy is converted to heat and dispersed into the air; thus, the brakes are more important in vehicle control. The braking system acts on the wheels; it is controlled by a foot pedal/hand. Friction resists the motion of the vehicle, when a moving vehicle is abruptly stopped by applying brakes. The motion of the brake shoes/pads creates friction between the brakes and the braking drum/disc and then tyre-road friction slows or stops vehicle motion. In the present scenario, the majority of low-weight vehicles employ disc brakes rather than drum brakes [31]. Thus, the tribological characteristics of discs and pads have a considerable impact on the braking process. The discs are often made of grey cast iron due to its excellent wear and frictional resistance, high thermal efficiency, and anti-vibration characteristics, but they are heavy in weight. So, discs made with composite materials have developed, particularly for sports cars. Brake friction components may wear out in many ways. The major prevalent kind of wear is abrasion, which occurs when friction parts rub against each other. Scratching, micro-grinding, and groove development cause the material loss of the pads.
Fluids
Published in Daniel H. Nichols, Physics for Technology, 2019
Automotive brakes work on a hydraulic system (Figure 8.28). They consist of a master cylinder, which is a reservoir of fluid, and a brake cylinder at each wheel. The master cylinder contains two pistons, one for the front and one for the back brakes. When the brake pedal is pressed, the pressure generated by the master cylinder is transmitted to each wheel cylinder, causing the brake shoes or the calipers to apply a mechanical pressure on the drums or calipers to slow the vehicle down.
Study on longitudinal dynamics of heavy haul trains running on long and steep downhills
Published in Vehicle System Dynamics, 2022
Wentao Liu, Shuai Su, Tao Tang, Yuan Cao
The air braking of wagons for HHTs mostly adopts brake-shoe braking mode. The main components of the air-brake unit is depicted in Figure S2. When the air braking is implemented, the air in the train pipe is discharged and the brake signal is transmitted from the locomotive brake valve to the brake unit of wagons via the train pipe. Then the air in the auxiliary reservoir flows into the brake cylinder through the control valve, which makes the pressure of brake cylinder increase. Further, the increased pressure acts on the brake cylinder piston to push the piston rod to move. After being amplified by the braking rigging devices, the force is imparted to the brake shoes to press the wheel tread, producing the friction to realise the braking function. The air braking force of the wagons can be calculated by the Equation (7) [29]. where is the pressure on each brake shoe. is the friction coefficient of the brake shoe; is the number of brake shoes equipped on the wagon.