Pyörimisveto

Pyörimisveto, often translated as rotational traction or torque traction, is a concept in vehicle dynamics referring to the grip generated by a wheel that is actively driven. It is distinct from braking traction, which is generated by a wheel that is being slowed down, and steering traction, which is generated by a wheel that is being turned.

In essence, pyörimisveto describes the force a driven wheel can exert on the road surface to propel the vehicle forward or backward. This force is a result of the friction between the tire and the road. The maximum pyörimisveto is limited by the coefficient of friction between the tire and the road surface, as well as the normal force pressing the wheel down. When a driver accelerates, the engine sends torque to the driven wheels, causing them to try and rotate. The resulting friction force at the contact patch is the pyörimisveto.

If the engine's torque demand exceeds the available pyörimisveto, the wheels will spin, a phenomenon known as wheel slip. Excessive wheel slip reduces the effectiveness of pyörimisveto and can lead to a loss of control. Modern vehicles often employ traction control systems to manage pyörimisveto, preventing excessive wheel spin and optimizing acceleration, especially on slippery surfaces. Understanding pyörimisveto is crucial for designing effective drivetrains and for drivers to safely control their vehicles.