Ohitusjärjestelmä

Ohitusjärjestelmä is a Finnish term that translates to "bypass system" or "overdrive system" in English. It refers to a mechanical system designed to alter the gear ratio of a vehicle's transmission, allowing the engine to operate at lower revolutions per minute (RPM) at a given road speed. This is typically achieved by introducing a gear ratio that is numerically smaller than a 1:1 ratio, meaning the output shaft rotates faster than the input shaft.

The primary benefit of an ohitusjärjestelmä is improved fuel efficiency. By reducing engine RPM, less fuel is consumed. Additionally, it can lead to a quieter driving experience and reduced engine wear, as the engine is subjected to less stress during highway cruising. Many modern vehicles incorporate some form of overdrive gear as a standard feature within their automatic or manual transmissions.

The implementation of an ohitusjärjestelmä can vary. In older manual transmissions, it might have been a separate unit or a specific gear selection. In automatic transmissions, it is often integrated as a dedicated overdrive gear or a set of gears that engage under specific conditions, such as higher speeds and lighter engine loads. The driver may or may not have direct control over engaging the ohitusjärjestelmä, as it can be automatically managed by the vehicle's transmission control unit. The presence and functionality of an ohitusjärjestelmä are key aspects of a vehicle's powertrain design, directly impacting its performance characteristics and economic operation.