In the early 1990s, Saab, long known as a manufacturer with unconventional engineering thinking, offered customers an unusual solution: the Sensonic manual transmission. Formally, it remained a "manual": the driver still shifted gears with the usual lever. However, one important element was missing in the cabin: the clutch pedal. The driver only had the accelerator and brake at their disposal.
In those years, Saab was often called "Swedish BMW." The company consistently focused on driving pleasure and, for this purpose, was not afraid to introduce technologies that stood out from generally accepted canons. Sensonic became one of the most illustrative examples of this approach.
The context for the appearance of this gearbox was quite clear. The end of the 20th century became a time when major cities around the world faced chronic traffic jams. Moving in traffic jams with a classic manual gearbox annoyed many: constant work with the clutch pedal in combination with the gear lever turned each trip into a tedious process.
At the same time, automatic transmissions of those years also had serious limitations. For drivers who valued dynamics, they often turned out to be too slow. In situations where it was necessary to accelerate quickly, for example, when overtaking, the automatic often began to slowly sort through gears instead of the expected sharp kick-down. This problem was especially acute in combination with turbocharged engines, and Saab was best known for such engines.
How Sensonic Was Designed
Saab engineers decided to preserve the advantages of a manual gearbox, избавив её от самой утомительной операции — работы со сцеплением. Так появилась трансмиссия Sensonic, в которой смыкание и размыкание сцепления осуществлял гидравлический привод под управлением электроники. В сам рычаг переключения передач встроили датчик: стоило водителю лишь приложить усилие к ручке, система автоматически размыкала сцепление.
This gearbox was installed on the turbocharged Saab 900 NG Turbo. Moreover, the proprietary Trionic engine management system was integrated with Sensonic, teaching it to adjust the throttle valve when the clutch was disengaged. Thanks to this combination, the car smoothly started from a standstill and accelerated confidently, and the gear shifting process was perceived as light and intuitive. Many drivers quickly adapted to the new scheme and spoke of it with sympathy.
An Idea Ahead of Its Time
However, by the end of the 1990s, the situation had changed. Saab replaced the 900 model with the 9-3 and simultaneously abandoned its original transmission. Over time, Sensonic revealed significant shortcomings.
One of the problems was the sensitivity of the system. Drivers sometimes accidentally touched the gear lever, and the gearbox instantly reacted, disengaging the clutch. At such moments, people got lost, and sometimes even frightened by the unexpected behavior of the car. A separate difficulty was starting on a hill: such a maneuver on Sensonic required skill and did not always go smoothly.
The key factor was reliability. The gearbox turned out to be difficult to maintain, and specialists at many branded service stations simply did not have enough experience with this transmission and were reluctant to repair it.
As a result, nowadays Saab with a Sensonic gearbox is a great rarity. Almost all owners of such cars eventually replaced the unusual transmission with a classic manual gearbox.
Was It the First?
Strictly speaking, the very idea of a manual gearbox without a clutch pedal was not unique. Long before Saab in Germany, starting in the 1960s, the Saxomat transmission was offered, which worked on a similar principle, но использовавшая электропневматический привод. In the same years, a version of the "Zaporozhets" for disabled people with a gearbox on a ferromagnetic clutch was developed in the USSR. All these solutions remained small-scale experiments.
Nevertheless, it was the Swedish company that first risked offering such a transmission to a wide range of ordinary car owners. Yes, this step turned out to be premature and was accompanied by technical compromises. But it was Sensonic that allowed Saab to write another unusual page in the history of automotive engineering.