Dennis,

You -DO- realize that when you post a link to a page full of
drawings of couplers (or whatever) to this list that you have
just "wasted" several hundred hours of time (collectively, the
combined time for which ever group members go look at the page
just to see what is there)?

"Gee, Dennis posted a link ... I think I'll see what's there ...
oh goody, there are lots of drawings of lots of couplers
at this link ...". And half an hour to 3 hours later we
come up for air. And our wives are hollering at us for
not getting our 'chores' handled. Etc., etc., etc.

To the OP,

Many couplers have just one "pin" that goes thru the body
of the coupler and it can be operated either from the top
or the bottom.
- Jim