 | Home > Technical > Bradley Auto Jaw |
 
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| blackwolf Member Since: 03 Nov 2009 Location: South West England Posts: 17444   
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I have one (which I have been intending to list for sale on this forum, since I never use it anymore) and it certainly doesn't do that.
My initial though is that tightening it up is very slightly deforming the hitch and causing the mechanism to bind, but it is hard to understand how this could be be since the hitch is much more massive than the receiver hitch adaptor it is bolted to. I will dig mine out this evening and stare at it for a bit to see if any ideas come to mind. They are clever couplings and work well, and as you say no-one can steal the pin. The only reason that I don't use mine is that I seldom tow my 1.1/8 ring coupling trailer any more, and when I do I tend to use the standard pin/jaw that I usually have with me. Expensive things too, those Auto Jaws. |
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8th Jun 2018 10:16am |
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| hank Member Since: 12 Sep 2016 Location: South Wales Posts: 2301 
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There is a sticker on the hitch that states the bolt torque to be 206Nm. I have tried nipping the bolts up tight, and then torquing them up to 206Nm, both result in the jaw not opening.
Initially I thought it may be warping but as you say, the hitch is a lot more substantial than the receiver drop plate. I wondered whether the moving parts were fouling the drop plate as they radius but 1. surely the design would not allow this and 2. it's not the case as I have tested it unbolted with a piece of board |
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8th Jun 2018 10:40am |
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| LandRoverAnorak Member Since: 17 Jul 2011 Location: Surrey Posts: 11324
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Has it been like this from new or is it a fault that has developed? Darren
110 USW BUILD THREAD - EXPEDITION TRAILER - 200tdi 90 BUILD THREAD - SANKEY TRAILER - IG@landroveranorak "You came in that thing? You're braver than I thought!" - Princess Leia |
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8th Jun 2018 10:46am |
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| rallysteve Member Since: 10 Feb 2014 Location: Cumbria Posts: 2237 
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I would whip it off and put a straight edge over the back of it see if the mounting face is flat.
Steve 02' 110 TD5 Double Cab Rebuild Thread |
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8th Jun 2018 11:03am |
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| jrule Member Since: 10 Aug 2015 Location: Hertfordshire Posts: 302 
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Sounds like something is wrong somewhere. When thinking of the loads when towing I would scrap and put a new one on.
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8th Jun 2018 11:47am |
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| VVS210 Member Since: 12 Nov 2016 Location: Hampshire Posts: 953
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Without seeing how it operates but watching the video, the obvious thing to me is that the drop down piece is fouling against what is behind it when the bolts are done up but when they are slack there is enough clearance for it to move. Have you tried moving it manually and doing the bolts up bit by bit to see at what point it stops moving?
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8th Jun 2018 11:56am |
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| blackwolf Member Since: 03 Nov 2009 Location: South West England Posts: 17444
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If you put two washers (one for each bolt) between the coupling and the mounting plate, does it still bind when tightened up?
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8th Jun 2018 1:33pm |
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| hank Member Since: 12 Sep 2016 Location: South Wales Posts: 2301
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Great suggestions thanks
Washers between hitch and drop plate make no difference so confirms it's not a fouling/clearance issue Have tried a straight edge over the back of the hitch - straight as a die. The hitch drop plate however not so much so I think the problem lies here. It's a Terrafirma one from Flatdog so would have expected better. It's bent towards the front of the vehicle at either side so opposite to what you would expect from towing heavy load. So looks like options are to find a better (flatter) drop plate or carry on with my traditional hitch with pin. |
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8th Jun 2018 2:07pm |
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| blackwolf Member Since: 03 Nov 2009 Location: South West England Posts: 17444
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If you have a traditional hitch, you could try bolting it on in place of the Autojaw with a narrow-ish vertical spacer in the middle, well clear of the bolt holes. If you pull it tight, it should straighten the drop plate. Then you could try the Autojaw again.
I must say that I am surprised that the relatively thin drop plate is, apparently, deforming the Autojaw. Do you have access to another vehicle with a known flat mounting face to which you could bolt the Autojaw to see if it then works? Has the Autojaw always done this, or has it worked properly in the past? Is it new? If so, I suggest returning it to wherever you bought it for a replacement. |
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8th Jun 2018 2:52pm |
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| hank Member Since: 12 Sep 2016 Location: South Wales Posts: 2301
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To be fair, the drop plate is about 10mm thick and quite big in terms of area so a lot of steel to bend back. I will have a go at straightening it though. Otherwise I am thinking of making up a shim to put between autojaw and plate to take out the bend.. Another job to add to the list
I got hold of the Auto Jaw used. They are expensive new as you know! |
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8th Jun 2018 3:00pm |
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| Scoobeenut Member Since: 04 Mar 2015 Location: West London Posts: 310 
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Try fitting the hitch upside down and see if the problem persists.
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8th Jun 2018 4:30pm |
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| blackwolf Member Since: 03 Nov 2009 Location: South West England Posts: 17444
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I've had a look at mine and compared it to your video, and although your camera angle makes it hard to be sure it looks as though the locking catch or sear on yours (the bit the lever lifts to allow the jaw to open) is snagging the drop plate. On my coupling there is good clearance behind the sear, but as far as I can see on yours there isn't. It looks from the video as though when tightened you can't operate the catch, rather than the catch operating but the jaw not dropping.
It's hard to see in the video if the sear isn't moving sideways off its locking pin, or if it's moving sideways as it should but then not lifting. The odd thing though is that if that was the problem than I'd expect shimming it out with washers to allow it to work, but you say it doesn't. You can see the clearance I mean at the top right in this photo: 
It's a shame you're so far away because this is such an intriguing problem! I presume you've tried lubricating the catch in case it's just stiffening. Here's a link to one of the most boring YouTube videos of all time! There are over nine minutes of this excirement! |
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8th Jun 2018 6:39pm |
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| blackwolf Member Since: 03 Nov 2009 Location: South West England Posts: 17444
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Did you ever find the problem with this?
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4th Mar 2019 9:19pm |
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| hank Member Since: 12 Sep 2016 Location: South Wales Posts: 2301
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I came to the conclusion that the bow in the drop plate was enough to cause the autojaw to jam.
I had intended to straighten the drop plate but moved abroad for work shortly after. It's on the list of things to do when I return in 2020! > 110 XS Double Cab |
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10th Mar 2019 9:57am |
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