The End Of The Clutch As We Know It?


The earliest gearboxes were a set of beveled reduction gears driven by the engine. These gears were connected to a shaft and pulley that were tied directly to the drive axle through a group of leather belts. There were only two gears. One to get going, the other to hit top speed. If the car could not climb a hill, the driver would have to stop, manually engage the lower gear, and hope it offered enough power to get to the top. It wasn’t until 1894 that the basis for the modern multigear gearbox was introduced by Louis-Rene Panhard and Emile Lavassor. Even then, the gearbox was simplistic…just three gears connected to a chain-driven rear axle. In 1898, Louis Renault invented the live axle connected through a drive shaft and, viola, the modern manual gearbox was born.

How A Manual Gearbox Works

Many of you reading may already know this, some may not. We are throwing it in here just for educational purposes and to lead into why everyone is working to eliminate the clutch from the modern transmission. With a hydraulic clutch, the master cylinder pushes fluid down the clutch hose to the slave cylinder. The slave cylinder then pushes the throwout bearing back, releasing the clutch plate. You are then free to select the gear that you want, and release the clutch. Simple, but basically accurate. Every step of the process creates friction that reduces the efficiency of the car. Automatic gearboxes work in a very similar way, sans the need for the driver to mess with shifting gears by hand; however, the friction still exists. Since every government in the developed world is focusing on increased efficiency from automobiles, engineers have been searching for ways to reduce weight and eliminate the friction within the gearbox. That may very well mean the clutch has a very dim future as anything other than a museum piece.   image-2

Technology On The Horizon


The manual gearbox could easily be placed on the critically endangered species list with the industry-wide focus on efficiency. One of the latest alternatives to the current clutch setup looks to eradicate friction discs, even from dual-clutch automatics. One gentleman who is researching ways to do so is Dan Dorsch, a Ph.D. candidate and National Science Foundation Graduate Research Fellow at the Massachusetts Institute of Technology(MIT). Earlier this year, he won the Lemelson-MIT ”Drive it!” award, a prize granted for the design with the best potential for societal benefit, economic success, and environmental impact.

To garner this award, he designed a hybrid-vehicle gearbox that replaces the traditional clutch or torque converter with a dog gear(a gear with interlocking teeth to couple the engine to the gearbox). The design does not completely eliminate friction, but it does significantly reduce it. In addition, the design reduces the size and weight of existing gearboxes. The main drawback to his current design is that it is intended for use in sports and supercars. The average economy ride will not benefit from the setup. 

How It Works

In Dorsch’s design, the gearbox mates the engine with two electric motors. The larger of the two will start the car off at the friction limit of the tyres. The smaller motor works within the gearbox, where its job is to rev match the engine and the wheels during shifts. The second motor has two additional roles: to act as a starter and a generator as conditions require.image

The larger electric motor fills the role of first and reverse gears, smoothly meshing the engine and stationary wheels. This removes the need for a torque converter. During gear changes, the larger motor continues to provide torque to the wheels while the smaller motor rev matches. The entire process takes place in milliseconds, much more quickly than your could ever hope to do so while declutching and throttle blipping. Dorsch hopes to gain precise enough control to eliminate the  friction cones from gear synchronizers, streamlining the gearbox even further. Theoretically, the technology could provide perfect, speed-matched shifts and eliminate a few kilos from the gearbox. If so, even the power-sapping clutches in dual-clutch transmissions could be eliminated in the near future.

The technology sounds great from an efficiency standpoint, but what about the fun of a manual gearbox? There is something personal and powerful about handling your own shifting duties. There is a definite thrill to downshifting into a turn and upshifting as you rap on the engine to pull back out of it. Driving aficionados understand this lament!