| | | quote | Originally posted by donj:
I suppose the clutch could be involved but that seems to be a real doppelganger. An interesting thought though I wonder how the big guy's do it
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The truck transmission setup I know of uses a double-acting pneumatic cylinder with a shift fork attached to the piston rod. Air solenoids supply compressed air to either end of the cylinder, while venting the opposing end.
Each shift rail has a linear position sensor. When the transmission is assembled, each shift rail is shifted forwards, backwards, and set to neutral. The TCM learns each of these positions.
It is critically important that the TCM only attempt to send torque through the transmission when it is fully in gear. A half-shifted gear could be damaged if one attempts to send torque through it. The shift rail sensors are important to know when one is in gear and ready to go.
It is also possible to add a mechanical interlock to prevent a fork from moving away from neutral, if any other fork is partially or fully in gear. This is to avoid an accidental transbrake situation...
Depending on the type of rail position sensor, if they're all using the same method of sensing (such as magnetic), you'll need to be on the lookout for crosstalk between the sensors. Also, solenoids generate magnetic fields, and they can interfere with magnetic position sensors, so watch out for that too. Getting electronics to work inside a hot transmission needs care.
Shifting is naturally a constant-force type of activity, so compressed air lends itself to that. But on a car if you don't have compressed air readily available, I guess you could try to do something electric.
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The clutch is better controlled with position. You can use an electric motor and ballscrew arrangement to replace the slave cylinder. You need a fast-accelerating motor for good clutch control.
As long as you make the screw long enough, you can dispense with a clutch adjustment mechanism. With a long enough screw, the clutch release movement works in one section of the screw, and as the clutch wears down, the back-and-forth movement shifts along the screw. Plan for enough screw length for the clutch lifetime.
You can expect to use a linear position sensor to measure the actuator rod movement, and control the motor with feedback.
| | | quote | Originally posted by donj:
Why will this not work on the 5 speed? inquiring minds want to know...........
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I don't see why a Fiero 5-speed couldn't be automated.
That said, I don't have experience with passenger-car "automated manuals". I really dislike the term automated manual... it's an oxymoron. If you can put it in drive, it's an automatic.
[This message has been edited by pmbrunelle (edited 09-21-2020).]
