9.1 State ONE difference between driving a vehicle fitted with an automatic gearbox to driving a vehicle fitted with a manual gearbox - NSC Mechanical Technology Automotive - Question 9 - 2021 - Paper 1

The torque converter serves multiple functions:

1. It multiplies engine torque and automatically transmits it to the transmission based on road and engine speeds.
2. It acts as a flywheel, helping to maintain engine operation during gear shifts and minimizing stalling.

A lockup clutch is used in torque converters to overcome slip that occurs inside the torque converter, allowing for a direct mechanical connection between the engine and transmission at higher speeds.

Stall speed refers to the condition when the impeller of the torque converter rotates at its maximum speed, but the turbine is almost stationary. This happens when the vehicle is stationary just before it starts moving or while the engine is idling.

A – Sun gear B – Annulus / Ring gear C – Planet gear D – Planet carrier

1. An epicyclic gear train allows the input shaft and output shaft to have the same axis of rotation, which simplifies the design.
2. It has a lighter weight and less inertia compared to traditional gear systems, resulting in improved efficiency.

The valve body detects the load and adjusts the gear ratio according to the torque requirements of the vehicle while directing the oil pressure to the correct hydraulic actuator.

The transmission oil is cooled by circulating it through a cooling radiator alongside the engine coolant radiator. This process helps maintain optimal operating temperatures, and some systems utilize oil coolers designed specifically for this purpose.