Timer schematic from 1976

Discussion in 'General Electronics Chat' started by tchampio, Apr 18, 2012.

  1. tchampio

    Thread Starter New Member

    Apr 18, 2012
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    Hello,
    I am trying to understand the 2 hand anti tie down ckt control of a 1976 Federal Press Co press.
    I don't have the actual timer component in front of me but I have a good ckt diagram and component layout diagram. On the component layout diagram the two timers have an "on" and "off" drawn on each respectively. R2 is "off", R3 is "on".
    Anyway, there are NO and NO(T.O.) and NO(T.C.) contacts drawn in the schematics and these I believe I correctly understand.
    My problem is on the R3 "on" tmr, the exist NO(O.L.) contacts drawn in the print. What does this mean?
    Thank you
     
  2. Ron H

    AAC Fanatic!

    Apr 14, 2005
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    I hope you don't really expect an answer without a schematic.
     
  3. tchampio

    Thread Starter New Member

    Apr 18, 2012
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    As I hope you can see, the contacts are only shown as contacts, not switch's with up/dn arrows. But they are labeled T.O./T.C.
    My area of interest is the R3 NO(O.L.)
     
  4. Ron H

    AAC Fanatic!

    Apr 14, 2005
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    Sorry, but I haven't a clue what that circuit represents. Maybe someone else can help.
     
  5. tchampio

    Thread Starter New Member

    Apr 18, 2012
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    Sorry I couldn't show more of the original.
    Basically, the two hand control is illustrated by the Run palmbuttons. Both have to be pushed down to run, if one is released the ckt opens and both PB's must then be released to energize R2. When both are pushed again (R1 is already on -not shown) power will flow thru R2 NO(T.O.) because it hasn't yet timed out.

    What possibly could R3 (O.L.) stand for?
     
    Last edited: Apr 18, 2012
  6. strantor

    AAC Fanatic!

    Oct 3, 2010
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    I would normally say that OL means "overload", but that doesn't make much sense looking at the drawing; it looks like your "OL" contacts are an integral part of the circuit and not a failsafe shutdown. In light of that, my best guess is that it means "ON LATCH" and I've got about 21% confidence in that answer. a oneshot output is another possibility I considered but that doesn't make a whole lot of sense though either.
     
  7. gerty

    AAC Fanatic!

    Aug 30, 2007
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    Usually..TC = timed closed TO = timed open
    And like strantor said OL usually means Overload, but apparently not in this case.
     
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