Cold Condition N to 1 Gearshift Blockage Analysis in a Manual Transmission Gearbox

Abstract

Manual transmissions are the preferred transmission for drivers who love sporty gear shifts. Manual transmission vehicles are cheaper, very efficient, and offer quick gear shifts. Worldwide manual transmission contributes to 36.15% and in India it contributes overall 80% of today's market share. The customers expect a very smooth gearshift which is a challenge to achieve in all ambient temperatures. In a gear shift event, the synchronizers synchronize the speed of the gears. The force applied at the gear shift knob, generates the cone torque and stops the rotating input shaft for the Neutral (N) to 1 gear shifting. The early morning gear shifts have high gear shift effort. This effort is getting reduced with the increase in temperature. This is due to the drag in the gearbox which is inevitable. This work focuses on improving the very first gear shift event of N to 1 after the engine crank from cold (8°) to hot (80°) condition. The static (engine off) and dynamic (engine on @ idle RPM) were also studied. Different oil grades were compared and analyzed to get the optimal oil for the gearbox application. After synchronization, the sleeve interacts with the dog teeth to complete the gear shift event. The block that occurs at the dog teeth to be overcome to enhance the gear shift quality. The analysis was performed using the gear shift quality assessment kit. The optimal design solution helps to reduce the gear shift forces and reduces the shift blockage.