Twisted chains revisited

Dalehelman
Dalehelman Member Posts: 2,414
in Trailer & Towing
Here is a great video I found on FB https://youtu.be/clj42no4DxY

  1. Hash  T@B Fun
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  • jgram2
    jgram2 Member Posts: 1,522
    As long as I don’t conflate twisted with crossed! Cool vid @Dalehelman! We still cross the chains as per the Purdue University video about towing.
    John, Judi, Guinness & OD in PDX
    T@Bit@t 2015 S Max Outback, ‘18 V6 4Runner 


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  • gspdx
    gspdx Member Posts: 208
    Great info.  Thanks for posting.
    2019 T@B 400 BDL
    2018 Ford F-150 2.7L Ecoboost with tow package
    PNW
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  • Bayliss
    Bayliss Member Posts: 1,496
    In addition to crossing the tow chains, I raise them to a safe height above the roadway by routing each chain through the attachment holes that are located on each side of the hitch receiver mount.  I then connect the chain hooks (with safety spring clips) to a link along the tow chain at the desired height.  That lifts the tow chain without twisting the links.

    Does anyone see any problem with doing it this way?  I have wondered if running those links once through the receiver mount (on each side of the hitch), rather than instead connecting the chain hooks directly to those mounts, could possibly weaken the strength of the links in the event the trailer pops off the hitch ball while towing.  [NOTE:  I connect my break-away cable directly (i.e., separate from the chain) to one of the the hitch receiver attachment holes using a "quick-link" connector.]  (Greg)


    2019 T@B 320 S Boondock Lite; 2025 Toyota Tundra CrewMax 4x4
    (Alde: 3020; Refrig: Isotherm Cruise 65 Eleg; Battery: BB 100Ah LiFePO4; Solar: Renogy 220W Portable Suitcase w/ Victron SmartSolar MPPT 75/15 Controller; Victron BMV-712 Battery Monitor w/ Shunt; Pwr Cntr: PD-4135KW2B; EMS: PI-HW30C)
    Greg & Marlene (Tucson, AZ)


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  • pthomas745
    pthomas745 Administrator, Moderator Posts: 4,529
    That is the way I do mine.


    2017 Outback
    Towed by 2014 Touareg TDi
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  • Bayliss
    Bayliss Member Posts: 1,496
    Cool.  Thanks for the input @pthomas745.
    2019 T@B 320 S Boondock Lite; 2025 Toyota Tundra CrewMax 4x4
    (Alde: 3020; Refrig: Isotherm Cruise 65 Eleg; Battery: BB 100Ah LiFePO4; Solar: Renogy 220W Portable Suitcase w/ Victron SmartSolar MPPT 75/15 Controller; Victron BMV-712 Battery Monitor w/ Shunt; Pwr Cntr: PD-4135KW2B; EMS: PI-HW30C)
    Greg & Marlene (Tucson, AZ)


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  • pthomas745
    pthomas745 Administrator, Moderator Posts: 4,529
    And, here is the link to the Purdue "Keep the Trailer Attached" .pdf. Page 42 is where safety chains are discussed.  And many photos of "how not to."




    2017 Outback
    Towed by 2014 Touareg TDi
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  • falcon1970
    falcon1970 Member Posts: 758
    @Dalehelman
    A very instructive video.  I wonder, though, what the failure point would have been if the test had been done with the chains twisted less, and not wadded up into a ball.  I still agree that twisting the chains reduces the max strength.  I also wonder what the strength reduction is with a sideways load on a single link--as when the chains are passed through the hitch attachment point and fastened back to the chain.
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  • tabiphile
    tabiphile Member Posts: 470
    falcon1970 
    I wonder, though, what the failure point would have been if the test had been done with the chains twisted less, and not wadded up into a ball.  I still agree that twisting the chains reduces the max strength. 
    The actual effect of a moderately twisted chain is minimal. Several available studies confirm that the effect is less than 5% of the overall tensile strength of the chain. Given that a properly selected chain would have a safety factor of significantly more that change is insignificant. The effect would be from the shock force of a chain jerk when a chain that is too long is engaged during a decoupling failure may actually be greater so pick your poison. 
    There are quite a few studies that include FMEA that highlight the effect of twist.
    Here are several related:
    http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.659.5486&rep=rep1&type=pdf
    https://mechanicalelements.com/twisting-safety-chains/

    Twisting to the point of overlapping links does have a more serious effect of the chains tensile strength...so some common sense is necessary. As has been said in the earlier discussion about this, there is no substitute for using properly sized and connected chains. But a few twists to shorten up a bit..your call if you do or don't. It should not be a major concern
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