D-Ring Harness Questions

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  • November 1, 2012 at 3:44 pm #44211
    Does’ Leap
    Participant

    I just bought a set of harnesses that have been sitting in a barn for 10 years. I washed and oiled them and will make one harness out of the two (for my new horse) by swapping out worn leather. The bolt in the D ring that holds the rear trace looked sketchy so I decided to replace it. Of course the bolt had a slotted head (for a screwdriver) and was rusted shut. I had to weld a nut to it to extract. I was surprised to see that the bolt diameter was only 5/16″ (much less after the ware – see picture). In my other harnesses, this bolt is at least 3/8″. Options:

    1. buy a 5/16″ grade 8 bolt (grade 5 pictured) and call it good enough;
    2. drill and tap a 3/8″ hole for a bigger bolt.
    3. others?

    Any thoughts on this?

    Sidenote: neither of these harnesses had a back pad or belly band. This is the second set of d-ring harnesses I have seen set up this way. I drove an older gentlemen’s team this winter with the same set-up. He said that is always how they ran their harnesses!? Any thoughts from the D-ring harness historians (remember the “origins” thread?)?.

    Thanks.

    George
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    November 1, 2012 at 10:58 pm #75673
    mitchmaine
    Participant

    hi george, maybe that 5/16 bolt had a bushing to help the tug wear better. that might make up for the extra 16th.
    never heard of pulling the saddle and girt off. we used to strip off the britchin and throw the tugs over their back for twitching single, but needed the saddle to hold the tugs in place. maybe the team was hooked into a yoke steady, but without a jack saddle the weight of the pole would hang on their collars. doesn’t seem like a good idea to me. let us know what you find out.

    November 2, 2012 at 1:14 am #75674
    Jay
    Participant

    I have acquired at least 2 pairs of New England D ring harness for parts over the years that have not had back pads of any kind. I could not figure out what the point of having a D ring is if there is not back pad, but I have seen it several times, so apparently some were set up that way. Jay

    November 2, 2012 at 11:00 am #75671
    Does’ Leap
    Participant

    I had the same question/comment on the harness (i.e. what’s the point?). I wonder if these harnesses preceded today’s d-ring and at some point someone thought they could get the weight off the neck by putting in a back pad? I harvested a back pad from another harness to put on this one.

    Mitch, I have a sleeve/bushing for this, but 5/16″ still seems wimpy. I think it is fine for farm work, but for logging it seems a stretch (perhaps I’m overthinking this?) Since I am mainly doing farm work with this horse and some firewood, I bought a grade 8, 5/16 bolt – should be fine.

    George

    November 2, 2012 at 1:17 pm #75669
    Carl Russell
    Moderator

    @Does’ Leap 37329 wrote:

    I had the same question/comment on the harness (i.e. what’s the point?). I wonder if these harnesses preceded today’s d-ring and at some point someone thought they could get the weight off the neck by putting in a back pad? ….

    If you remember from our research, it seems as though the ring in the harness had many manifestations that were for apparently other reasons, like shortening the required length of leather, or for easier repair, and that some harnesses that are not designed to hold weight on the jack saddle still have one, even without a d-ring.

    All of these different features all seem to have converged “by accident” into what is now known as the NE D-ring Harness. The truth of the matter is that I’m sure most folks never really cared whether the tongue weight was carried on the neck or on the back. As is true with most things, it still gets the work done.

    Obviously a correctly adjusted backpad and harness will afford the horses the ability to hold tongue weight on the back, but if the harness is not adjusted correctly, or hitched too loosely then the backpad is useless, and the weight is on the neck again.

    I would have to say that one of the primary reasons for having backpad and belly band is for adjusting draft angle. This again is only a matter of teamster concern, as there are a lot of horses out there working with poor draft angle.

    In the modern context, efficiencies like draft angle and tongue weight are more appropriate than they were a hundred years ago when horses came a dime a dozen, and every Tom, Dick, and Harry was working them with whatever got the job done.

    Carl

    November 4, 2012 at 4:45 am #75676
    fogish
    Participant

    Does Leap, a 5/16″, grade 8 bolt has a shear strength of 6900 lbs, a proof load of 6300 lbs, and a min. tensile strength of 7800 lbs. Another part of your harness is more likely to fail before that bolt, I think.

    November 4, 2012 at 11:33 am #75670
    Does’ Leap
    Participant

    Fogish:

    That is interesting and reassuring information. I searched “bolt strength” after I read your post and found an informative table http://www.almabolt.com/pages/catalog/bolts/proofloadtensile.htm.

    I should have figured this info was available. Now I can rely on data rather than my “sense” that something might be under-engineered. In this context is it fair to assume I should be looking at proof load (“The tension applied load that a fastener must withstand without any indication of permanent deformation or failure”) as a opposed to shear strength?

    Thanks.

    George

    November 4, 2012 at 7:15 pm #75672
    grey
    Participant

    Looks like that trace clip has seen some pretty good wear also.

    November 5, 2012 at 3:46 am #75675
    fogish
    Participant

    Correct, proof load will be the biggest factor when used in a D-ring. Once you cross that threshold it will deform permanently, but if you don’t go too far it will not break, and you will want to replace the bolt. The tensile strength is what it takes to lengthen or pull apart the bolt. The shear strength is what it would take to essentially use the same force/action as scissors/shears on the bolt. I doubt your tugs will be able to do that.

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