Toyota Files Patent on New Manual Transmission Technology Found on 1960s Saabs

The more things change, the more they ... freewheel down hills?

Toyota / Saab

Toyota is looking into ways for us to keep our beloved manual transmissions, while still meeting the ever-more-stringent fuel efficiency and emissions demands of the future. That's great! The slightly puzzling thing, though, is that the automaker's newest idea isn't really all that new.

, Andrew Krok discovered In short, the envisioned electronic device would allow traditional manual-transmission vehicles to automatically slip into neutral to coast down hills, without driver input. The system would also prevent the driver from accidentally shifting into a gear that could lead to engine damage—say, a high-RPM inadvertent downshift from 5th to 2nd.

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As Krok points out, the automatic neutral engagement could go a long way toward keeping manual transmissions around in future vehicles. With the car selecting neutral on its own for downhill coasting, engineers could incorporate the auto-stop-start systems currently found in many automatic vehicles. It could also allow for autonomous braking systems: The car could shift itself into neutral in a panic stop, thereby not stalling out.

As with most patents, the exact methods of how the system would accomplish these tasks aren't abundantly clear. And there's nothing to indicate that Toyota plans on including this technology in future production cars. Corporations frequently patent new ideas preemptively, just in case there's a use for it somewhere down the road. Our hunch is that this is just such a preemptive patent.

But there's a kind of funny parallel here, and it has to do with old 1960s Saabs. Because a manual transmission that pops itself into neutral to save fuel by coasting down hills sounds a lot like the freewheel mechanism used in the Saab 93 (introduced in 1956) and the 96 that followed (of which a 1967 model is shown above).

See, early Saabs used two-stroke engines, where oil was mixed with the fuel and there was no separate engine lubrication system. At part- or full-throttle, these engines ingest enough oil-laden fuel to adequately lubricate the pistons, but at closed throttle—say, if you were engine-braking down a hill—the engine could be dangerously starved of lubrication.

Saab rectified this with a freewheel mechanism that let the wheels spin faster than the engine on downhills. So you'd coast along with the engine idling, minimizing the motor's lubrication demands while still maintaining your road speed. Other cars as far back as the 1930s used similar freewheel systems, either to reduce engine stress or to save fuel, but the Saab two-stroke system is the one we're most familiar with—and likely the most widespread application, given that Saab mass-produced two-stroke cars until 1980.

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Of course, Toyota's high-tech idea isn't directly comparable to the simple freewheel found in old Saabs, and it's engineered to solve a whole spate of problems that the Swedish designers of the 1950s and 60s never had to consider. But it just goes to show that, in this great big world of automotive engineering, what goes around comes around. And sometimes, it comes around freewheeling.

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