Re: U vs TU

Posted by Rusty O\'Toole On 2010/8/30 21:59:14

It's worth keeping in mind that the wonderful feature of the first Ultramatics was that they did not shift gears at all. This had been the dream of engineers and drivers for years, to make a car with no gearshifting that drove as smoothly as a steam or electric car.

With the invention of the torque converter this dream seemed within reach. A torque converter has the unusual property that it slips and allows the engine to idle without stalling, then picks up the torque as you pull away and actually multiplies it like a gear ratio. As the car speeds up the torque converter tightens up to a near 1:1 ratio. Packard even included a lock up clutch to eliminate slippage once you got up to speed.

This was practically a transmission in itself. All they had to add was a reverse gear for backing up and a low gear for emergencies such as starting on a steep hill or pulling through heavy sand, snow or mud.

Only later did it seem like a good idea to add more gears under the demand for more performance. The gear start 2 speed was the first step in this direction, in the end they would no doubt have gone to a 3 speed torque converter trans as Chrysler did in 1957 and GM in 1964. Today you can get 4, 5 and even 6 speed transmissions. Such transmissions would have been considered a hopeless failure to the engineers of the 40s.