Educational interlude

Even for those of us who live in places which are essentially manual-only, city buses have conventional torque converter automatic transmissions.

We get them from ZF:

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and Voith (pronounced Foyt, it’s the origin of the racing family’s name)

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Americans tend to get them from Allison:

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All these have something in common. No Park position. Why?

Weight. Park works by using a pawl to lock a toothed wheel thus providing a mechanical lock. If you tried this on a heavy truck or bus you’d find that if the park pawl was actually holding the vehicle the pressure exerted would be such that getting out of park could be impossible.

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So there you have it. Every day we learn something new.

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