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gaps in understanding of tv cable's effect on line pressure?

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    gaps in understanding of tv cable's effect on line pressure?

    Hey zoomie!

    I've been educating myself on transmissions, and on the AOD in particular, but of course; and am still confused on a point.

    If I designed an all-mechanical transmission, I would have regulated/governed pressure, and then I would have line pressure.
    I'd think that since you really don't want any gears to slip, that line pressure would be generated by the pump and any excess bled off, to achieve a constant. Just like your oil pump always does 40psi.
    Too little would let bands and clutches slip, too much would blow out seals.

    Then I'd have governed pressure, and this would be the "computer," where say 0-10psi would hold the valves in a first gear position (or rather, springs would overcome the pressure and the valves would remain in first gear), 10-30psi might start pushing some valves back against their springs, valves move and reroute the line pressure, some bands apply some clutches release, and you're in 2nd.
    Then I'd have two opposing inputs: the governor would regulate governed pressure, allowing pressure to rise the faster it spun, so you go into the next and then the next gear upshifting.
    Then I'd have the tv cable opposing that, so that past a point, approaching WOT, it would cut down governed pressure and you'd downshift again.
    I'd also have the manual shifting lever do something of the same thing, between D1, D, and OD: D would have a bleeder valve never allowing governed pressure to rise high enough to go into OD, D1 would have an even lower pressure bleeder, so you never could go into OD, 3rd, or even 2nd gear.

    And there are vacuum regulated transmissions, where when the vacuum drops low enough (read: WOT), you downshift/ kick down.


    However, I've heard that the AOD is different: that tv pressure doesn't just control kickdown, like the vacuum operated C4, but it also regulates line pressure.
    Why would they do that?
    Now, I know too from setting my tv cable spacing, that line pressure cannot be the same as regulated pressure. I put a pressure gauge in the test port, and sure enough, at closed throttle I have 0psi, and as i pull on the cable, I get 10, 20, 40, 60psi for example the further I pull it.
    But of course, you DO drive with a closed throttle, and 0psi wouldn't hold a sheet of paper to a table against a light breeze, so line pressure needs to be higher than that.
    Does governed pressure rise with higher gears too? (I could test tv pressure, but didn't have an easy opportunity to test gear selection and pressure-- although I guess I could have raised up the car and driven it on jackstands to see what happened in 1st, 2nd, 3rd, or 4th gear: whether that pressure rose.
    Does governed pressure suddenly drop at wide open throttle, to tell the transmission to kick down? (here again, I did not pull the tv cable all the way, to find out. it never occurred to me to ask at the time I was setting my tv cable)

    Is the idea that line pressure rises with throttle opening, to hold the clutches and bands with more and more pressure?

    So if your tv cable is adjusted with slack, or is off entirely, you'll get early shifts, and weak shifts, and clutches and bands will be held weakly so it'll slip under lighter loads?


    I *think* I have full understanding here, but I don't know... is all of the above correct, or do I have some misconceptions here?

    thanks!!
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