COUPLING PERFORMANCE AND CONVENIENCE

nlike electric motors or even steam engines, internal combustion engines cannot generate torque when at a standstill and thus cannot be directly coupled to the gearbox and the rest of the drivetrain. In addition, they have limited minimum and maximum operating speeds and an even more limited torque range within these operating speeds. Matching engine output and speed to the required acceleration, speed and gradeability capabilities of the vehicle necessitates a transmission with a spread of gear ratios. Moving a vehicle from a standstill requires the progressive coupling of the moving engine with the stationary drivetrain; the degree of engagement is carefully controlled to keep the engine within its operating range while the vehicle gathers speed. Manually operated gearboxes (M/T) and dry friction clutches – where the driver must select the appropriate gear ratio and