Got a nice 955 (on left) and a real nice parker union 975b (right). Both have 5" jaws, the 955 opens 7.5", 975 opens 9".  My questions about the 975 are why is there a roll-pin installed in the head of the swivel loose/tightening bolt? factory?  also there seems tobe a plug on the left side base where maybe one could install the swivel loose/tightening bolt instead of the right side, am i correct thinking this?  Whats the B mean?  maybe used after union took on the the line. Thanks 4 any help.

My guess would be the roll pin holds onto the foot under the bolt in case you unscrew the bolt all the way...
(Otherwise it would go around the circle and you would have a heck of a time getting the bolt back in)

Quote from: rusty on May 12, 2013, 09:18:06 PM
My guess would be the roll pin holds onto the foot under the bolt in case you unscrew the bolt all the way...
(Otherwise it would go around the circle and you would have a heck of a time getting the bolt back in)

it doesn't go thru the bolt lengthwise, its really a unique locking setup, i don't understand it yet, got to take it all apart to figure it out, 3-4 pieces consist of the base.  thanks.

Hey, Wrenchguy:
I was looking at the paint on your 955 and noticed it seems similar to that on my 39 in another thread (black w. orange around the jaws.)  Do you know if they were originally finished this way or just an interesting coincidence?

No clue on the roll pin.  The 975 'B' is probably a design revision or maybe a 975 has no swivel. I have found swivel mounts to be a pain. When you try to twist or bend something, the swivel slips.  The boss may  have been cast for a left side swivel option, but my guess is that the PO drilled and pinned it to keep it from slipping. I would.