Evaluation of Compatibility of Elastomeric Component of Master Cylinder with Brake Fluid

Abstract

Importance of proper functioning of braking system of any automobile is imperative for ensuring safe operation. Master cylinder is a heart of the brake system and rubber seals and cups are its vital parts. Specially processed and designed seals resist leakages and transformation due to temperature changes or reaction with the brake fluid. This paper presents the compatibility study conducted on two different rubber materials, NBR and SBR-EPDM (identified by FTIR) used for master cylinder seals. The rubber seal samples were aged in the brake fluid at a temperature of 78+/-2°C in an oil-bath for duration of 4–6 weeks till the attainment of equilibrium weight. Properties like appearance, weight, volume and hardness were periodically measured after immersion. Similarly, after completion of immersion cycle and its measurement the samples were oven dried at 100+/-2°C till attainment of equilibrium weight and the measurement step as above was repeated. Brake fluid after aging was also evaluated for presence of rubber materials. Assessment of material compatibility of these two sets of rubber components after ageing showed distinct differences in above property performance. This emphasizes the need for the evaluation of compatibility of rubber seal materials prior to its use to avoid field failures.