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Thread: Cat 12 8T

  1. #1
    Join Date
    Sep 2018
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    19 Windy Ridge Lane Whitehall Mt
    Posts
    6

    Default Cat 12 8T

    When I purchased my 8T it had a chain around the front axle and hooked to the circle Drawbar. Found out why.
    The pivot ball had unscrewed from the threaded mount in the circle frame.
    I have gotten it threaded back in but have a couple questions. Could not find any information pertaining to this.
    How much space do I leave between the ball and circle frame. Does it use a key in one of the 3 keyways that are cut? Mine had a 1/8" plate up into the keyway and the cross bolt through it to keep it there. Surely not the width of the keyway.
    Apparently from lack of grease, it bent the 1/8" and began unscrewing with up and down blade movement.
    Can someone enlighten me as to what I should do. Besides grease it.

  2. #2
    Join Date
    Nov 2006
    Location
    Gold Coast, Queensland, Australia
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    4,731

    Default How Much????????????

    Hi, fishnhuntr.
    I have never had one of those draught balls out but my understanding is that you screw them up tight to the draught frame and then lock up the clamp bolt(s). The collar between the thread and ball is supposed to be tight up against the draught frame to help stop any shock load bending of the thread.

    If the ball was locking up in the socket, I doubt it would be lack of grease, although that may have been a contributing factor. I think it may be more likely that somebody took out too many shims from the collar that holds the draught ball in the socket and caused it to lock up on the ball. Always 'ass-yew-ming'of course that we are talking about the same parts.

    Photos help a lot when posting and answering questions like this.

    Just my 0.02.
    You have a wonderful day. Best wishes.

    Deas Plant.

  3. #3
    Join Date
    Sep 2018
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    19 Windy Ridge Lane Whitehall Mt
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    Default

    Quote Originally Posted by Deas Plant. View Post
    Hi, fishnhuntr.
    I have never had one of those draught balls out but my understanding is that you screw them up tight to the draught frame and then lock up the clamp bolt(s). The collar between the thread and ball is supposed to be tight up against the draught frame to help stop any shock load bending of the thread.

    If the ball was locking up in the socket, I doubt it would be lack of grease, although that may have been a contributing factor. I think it may be more likely that somebody took out too many shims from the collar that holds the draught ball in the socket and caused it to lock up on the ball. Always 'ass-yew-ming'of course that we are talking about the same parts.

    Photos help a lot when posting and answering questions like this.

    Just my 0.02.
    Thanks for the reply
    Will try to attach photos
    The key ways in the threaded end of the ball are about 3/16" wide without measuring. There is no key in there. Instead a piece of 1/8" plate.
    I plan to use whichever size plate 3/16 or 1/4" to fit the key way After I tighten the ball as suggested -- right against the frame.
    Does not appear to be any visible shims.
    I will check tightness of the ball in the socket when I tighten the ball into the thread more.
    Thanks
    Attached Images Attached Images

  4. #4
    Join Date
    Nov 2006
    Location
    Corralitos, Ca.
    Posts
    14,600

    Default

    Your right, not much info out there. Apparently there is a bolt and lock for the pivot bolt assuming to hold position once tightened. Did find this in a later model service manual.
    Check circle drawbar and socket adjustment the following way.....

    Lift the blade, then put a bar between the drawbar and the ball socket. Push the drawbar away from the socket, then remove the bar. Measure the clearance between the ball and the cap. Use shims as needed to get a clearance no greater than 0.062".

    If the ball has been running loose for some time the threads may be worn to the point where the normal lock may not hold irregardless of adjustment. I hate to suggest it but may be time to get out the welder.

  5. #5
    Join Date
    Sep 2018
    Location
    19 Windy Ridge Lane Whitehall Mt
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    Default

    Quote Originally Posted by Old Magnet View Post
    Your right, not much info out there. Apparently there is a bolt and lock for the pivot bolt assuming to hold position once tightened. Did find this in a later model service manual.
    Check circle drawbar and socket adjustment the following way.....

    Lift the blade, then put a bar between the drawbar and the ball socket. Push the drawbar away from the socket, then remove the bar. Measure the clearance between the ball and the cap. Use shims as needed to get a clearance no greater than 0.062".

    If the ball has been running loose for some time the threads may be worn to the point where the normal lock may not hold irregardless of adjustment. I hate to suggest it but may be time to get out the welder.
    The welder was my last choice haha
    Will try the thicker keyway material first and keep an eye on it.
    Appreciate the help. Thanks Dick out Montana way

  6. #6
    Join Date
    Dec 2006
    Location
    victoria australia
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    3,035

    Default 8B8282 Circle Drawbar/A Frame Ballstud Lock

    Hi Team,
    from memory the said lock is a Tombstone shaped washer, with a bolt hole in it for the clamp bolt to pass thru, also I think it needs to be slightly thinner than the split gap for clamping the ballstud bolt thread in the end of the drawbar/A frame so it does not impede clamping the ballstud bolt thread.
    I would expect the lock is available at a Dealer or used parts supply house.

    OM has given the later Manual adjustment procedure for the ball in the socket cap.
    Sometimes we used to machine some off the flat mount face of the cap if the joint was still loose with no shims fitted.

    For the Ballstud lock groove setting I would suggest using only one thick shim washer to set the Ballstud lock groove position as thin shims seem to fail, walk out, under vibrating loads.
    Work out the spacer shim dimension with thin shims with the ballstud tight --remove, measure and machine a suitable thickness spacer shim.

    Cheers,
    Eddie B.
    Last edited by edb; 08-17-2019 at 03:15 AM.

  7. #7
    Join Date
    Sep 2018
    Location
    19 Windy Ridge Lane Whitehall Mt
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    Default

    Quote Originally Posted by edb View Post
    Hi Team,
    from memory the said lock is a Tombstone shaped washer, with a bolt hole in it for the clamp bolt to pass thru, also I think it needs to be slightly thinner than the split gap for clamping the ballstud bolt thread in the end of the drawbar/A frame so it does not impede clamping the ballstud bolt thread.
    I would expect the lock is available at a Dealer or used parts supply house.

    OM has given the later Manual adjustment procedure for the ball in the socket cap.
    Sometimes we used to machine some off the flat mount face of the cap if the joint was still loose with no shims fitted.

    For the Ballstud lock groove setting I would suggest using only one thick shim washer to set the Ballstud lock groove position as thin shims seem to fail, walk out, under vibrating loads.
    Work out the spacer shim dimension with thin shims with the ballstud tight --remove, measure and machine a suitable thickness spacer shim.

    Cheers,
    Eddie B.
    I tried to tighten the ball up flush. However it does not get any tighter than about 1" if space left. Acts as though it has ran out of threads and acts striped. The ball screwed in with the threading about 3" and then acts like no more threads. The lock plate ( used as the key) is only about 1/8" thick. Tightening the cross bolt as tight as possible, the ball can still be turned, so I fail to see how the cross bolt can squeeze the area around the threads tight enough to keep the ball threads from turning. The frame area there is quite massive for it to squeeze any at all.
    As a result the key is the only thing keeping the ball from unscrewing.
    Am I missing something here.
    Plan to use the grader a bit and note for any movement of the ball. If it does move out, I will have to do the unthinkable-- weld it in place.
    Attached Images Attached Images
    Last edited by fishnhuntr; 08-24-2019 at 09:24 AM.

  8. #8
    Join Date
    Dec 2006
    Location
    victoria australia
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    3,035

    Default 1953, No 12 Grader Sales Brochure

    Hi Team,
    as I cannot post pix at present I will try and explain a drawing inset of the ball stud set up as shown in a No 12 Grader Sales Brochure :- Form No 10279A, Dated 1-53.
    The collar of the stud appears to be flush with the front on the A frame split clamping mount.

    There is only looks to be about 3 to 4 inches of thread on the outer end of the stud.

    The rear end of the stud--threaded end--is about flush with the end of the mount.

    It seems that someone may have crushed the split mount by tightening the clamping bolt when the stud was not in fully engaged position and so the stud will not screw all the way in. OR the threads are stripped due to the stud being pulled out when the stud was only just into the first few threads of the mount.

    I would try and unscrew the stud out and inspect its threads and put a wedge into the clamping split to assist refitting if the stud threads are OK.
    If threads are damaged then place a wedge into the clamping mount split to round up the thread bore in it, and then borrow/hire a suitable thread tap to reclaim the mount threads--likely best screwed in from the rear so as to pick up undamaged threads so it can reclaim the damaged area--if screwed in from the front it may damage any good remaining threads at the rear by being out of sync with the good threads further back inside is about all I have to offer at this point.

    Cheers,
    Eddie B.

  9. #9
    Join Date
    Sep 2018
    Location
    19 Windy Ridge Lane Whitehall Mt
    Posts
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    Default

    Quote Originally Posted by edb View Post
    Hi Team,
    as I cannot post pix at present I will try and explain a drawing inset of the ball stud set up as shown in a No 12 Grader Sales Brochure :- Form No 10279A, Dated 1-53.
    The collar of the stud appears to be flush with the front on the A frame split clamping mount.

    There is only looks to be about 3 to 4 inches of thread on the outer end of the stud.

    The rear end of the stud--threaded end--is about flush with the end of the mount.

    It seems that someone may have crushed the split mount by tightening the clamping bolt when the stud was not in fully engaged position and so the stud will not screw all the way in. OR the threads are stripped due to the stud being pulled out when the stud was only just into the first few threads of the mount.

    I would try and unscrew the stud out and inspect its threads and put a wedge into the clamping split to assist refitting if the stud threads are OK.
    If threads are damaged then place a wedge into the clamping mount split to round up the thread bore in it, and then borrow/hire a suitable thread tap to reclaim the mount threads--likely best screwed in from the rear so as to pick up undamaged threads so it can reclaim the damaged area--if screwed in from the front it may damage any good remaining threads at the rear by being out of sync with the good threads further back inside is about all I have to offer at this point.

    Cheers,
    Eddie B.

    Thanks. I will try the wedge and see if it will screw in any more. It was unscrewed when I started and it took the threads and threaded in until the last inch. Will see what happens when I wedge it and try.
    Appreciate all help that has been given.
    Have a great day

  10. #10
    Join Date
    Nov 2006
    Location
    Pittsford NY
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    4,370

    Default

    I think you need to get the gas out and open up the part where the clamp bolt passes through such that the ball thread can screw all the way back so the flange is flush. Then put the lock tab in there and do a trial tighten to see if it will clamp the ball thread tightly. If not, you can grind down the locktab so that the part that is in the clamp is thinner than the part that locates in the keyway. You can also grind the inside surfaces of the clamp split. You want that ball thread screwed all the way in to be able to retain it. I don't think you need to weld, if you can spend a bit of time with the gas and straighten things out.
    Cheers,
    Neil.

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