Pysäytyssuhteen

Pysäytyssuhteen, meaning "stopping ratio" in Finnish, is a concept used in the analysis of brake systems, particularly in the context of vehicle dynamics and braking performance. It quantifies the relationship between the deceleration achieved by a braking system and the deceleration that is theoretically possible given the available friction between the tires and the road surface. In essence, it indicates how effectively a braking system can utilize the available grip to slow down a vehicle.

A high pysäytyssuhteen suggests that the braking system is efficient and is able to apply braking force close to the limit of tire adhesion. This results in shorter stopping distances. Conversely, a low pysäytyssuhteen indicates that the braking system is not fully utilizing the available grip, perhaps due to limitations in brake force application, system design, or the presence of anti-lock braking systems (ABS) that may intentionally limit peak braking force to maintain steerability.

The calculation of pysäytyssuhteen typically involves comparing the actual deceleration measured during a braking event with the theoretical maximum deceleration, which is determined by the coefficient of friction and the vehicle's weight. Factors influencing pysäytyssuhteen include the type of brakes (e.g., disc or drum), brake pad material, brake disc condition, tire condition, tire pressure, and the state of the road surface. Understanding and optimizing pysäytyssuhteen is crucial for developing safe and effective braking systems in various applications, from passenger cars to heavy-duty vehicles and even in fields like railway engineering.