For this evening’s automotive oddity, let’s meet the Smiths Easidrive.
Smiths, as owners of old British cars will know because the name appears on the instruments, were a British automotive components maker.
In the late 1950s an American forklift maker called Eaton Yale developed a new kind of electrically operated automatic transmission which used an electric clutch that they had previously developed. They then hawked this around US car makers. There were no takers because Packard had been badly burned on something similar so after trying various potential customers in Europe they met up with and sold the transmission to Smiths. Smiths in turn developed it into the Easydrive and sold it to the Rootes company who wanted something to sell to the Americans.
In the event it proved to be unreliable in its early versions and although it was improved the marketing damage was done and it was dropped after three years. Rootes went into a decline and shortly after sold out to Chrysler who wanted an easy way into the European market.
So, what was the Easydrive?
It was a three speed mechanical gearbox with two electromagnetic clutches - when a current was applied an electromagnet attracted metal filings to itself with sufficient force that they became a solid enough mass to transmit drive. One clutch drove the wheels directly (top gear), the second drove two sets of intermediate gears (first and second) and reverse. Having started in first and built up enough speed, second gear would be engaged. First remained engaged but as it had a freewheel it was in effect bypassed. Having achieved more speed the system engaged the top gear clutch and disengaged the first/second gear one, thus unexpectedly operating as a twin clutch gearbox.
Here’s the only picture I could find, showing the two drum shaped clutches on the right the intermediate gears in the middle and the sliding reverse pinion to the left.
Apart from unreliability, one of the issues was that the load imposed by electromagnets, lights, ignition and wipers was about as much as electrical systems of the day could cope with and any problems with the charging system rapidly resulted in a flat battery and no gears.
So there you have it. One of the first automated manual transmissions.
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