Jarrutustehoon

Jarrutusteho, or braking power, denotes the rate at which a braking system dissipates the kinetic energy of a moving vehicle as heat. It is the power with which the braking force reduces the vehicle’s energy, and at the wheel it can be expressed as P = F · v, where F is the braking force and v is the instantaneous vehicle speed. Equivalently, braking power is the derivative of kinetic energy: P = -d/dt (½ m v^2).

The maximum achievable jarrutusteho is limited by tire–road friction and the available braking force. The force at the tire contact patch is constrained by the normal load and the friction coefficient μ, so Fmax ≈ μN. Since power increases with speed, higher speeds allow greater potential braking power for the same braking force, but temperature, pad material, rotor condition, and road surface affect actual performance. The braking torque T applied to a wheel relates to power by P = T · ω, where ω is the wheel’s angular velocity (ω = v/r for wheel radius r).

Braking systems and phenomena affecting jarrutusteho include hydraulic or electric actuation, disc or drum brakes, and control features such as anti-lock braking systems (ABS) that prevent wheel lock and help sustain braking power by maintaining optimal tire grip. In electric and hybrid vehicles, regenerative braking can influence the distribution of available braking power between mechanical brakes and energy recuperation.

Applications of jarrutusteho measurements include performance testing, braking-distance calculations, safety assessments, and efficiency analyses. Accurate assessment requires consideration of speed, tire condition, brake temperature, and road surface to reflect real-world braking behavior.