Transmission system for motorcar

Since the early days of the automobile, gearbox-related inventions and patents have been numerous, and will continue to be so, as developments linked to hybridization and even full vehicle electrification go hand in hand with new gearbox architectures.

There are many different types of gearbox, often based on very different concepts, each claiming different qualities in terms of performance or comfort.

In our first article [BM 2 586] , we described three concepts that are quite similar in their basic architecture: the manual gearbox, the automated manual gearbox and the dual-clutch automatic gearbox.

In this article, we focus on converter automatics and continuously variable transmissions, two concepts that monopolize the market in the USA and Asia. Converter automatic transmissions as we know them today have been around since the middle of the last century. They are therefore a tried-and-tested concept, but one that is constantly being improved to meet ever-higher performance levels. Continuously variable gearbox concepts are numerous, but often less compatible with current technological and industrial constraints. We will therefore limit ourselves here to describing two concepts that are or have been in series production: the belt drive and the toroidal drive.

We also provide some comparative performance data for all the main types of transmission (manual gearbox, automated gearbox, dual-clutch gearbox, automatic converter gearbox and continuously variable transmission), focusing on efficiency and fuel consumption.