Clevis Vs. Shackle Vs. Clevis . . . PLEASE define . . .

RonHebbard

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Decades ago, if I called something a clevis someone would correct me explaining it was a shackle. You can see where this is going. If I called something a shackle, I'd be told I was wrong, it was a clevis. About a week ago I asked CB if we could make this a 'Question Of The Day' as the current question about the quantity of dimmers has been up for many a moon. I was told my query could not be posted as a Question Of The Day as I couldn't provide an answer. Silly me! I didn't know a Question Of The Day couldn't be posted without a succinct / definitive answer.
Next I took my query to a friend of some 30 years who's spent at least the last two decades teaching college level millwrighting to folks apprenticing to become journeyman and / or Master millwrights. My associate provided two PDF's from his course of study but, in typical college fashion, I perceive them to be verbose and far from concisely definitive. I questioned my friend further and the more he looked into this, the more convoluted the differences and similarities become.
Thus my query: @egilson1, @Whatrigger, @derekleffew, @dvsDave, @skatersdad and @anyone else.
What are the definitive differences between a clevis and a shackle?
From the digging I've done thus far, here's where things seem to be heading:
It appears a clevis is a three piece coupling device with two parts attached / welded to items and only one loose, non-attached, piece with that piece being a clevis pin.
For example: You may find the female portion of a clevis welded to the frame of a tractor or caterpillar-tracked bull dozer and the male portion of a clevis permanently attached to the tongue of a trailing device; such as a cart, plow or tiller for instance with the only loose, readily removable, part of the clevis being the clevis pin.
Typically, the clevis is arranged to afford a reasonable amount of vertical movement or play and an appreciable amount of lateral movement. A shackle, on the other hand, appears to be a two (versus 3) part device with both parts loose / conveniently transportable, such as shackles often used to temporarily couple items used in rigging.
Some sources informed me that clevises had non-threaded clevis pins while shackles ALWAYS had threaded shackle pins although sufficient Googling appears to show both clevises and shackles with threaded and non-threaded pins.
Come one, come all. Please educate and elucidate this poor old blind geezer.
Toodleoo!
Ron Hebbard.
 
Well you have me interested Toodles. I thought Clevis was just an old term for Shackle, possibly a brand name from back in the day.

@porkchop would be another good person to call out.
 
Since Bill gave a real response I'll repost my original answer before I rethought the QotD rules:

My understanding is that clevis is a more generic engineering term for a load bearing element where the load is inserted within the device and then secured with a pin of some type. A shackle is a specific tool made for rigging. I also feel like the straight walls of the clevis that are designed for some amount of rubbing against the load are an important element of a clevis that generally you don't want on a shackle.

Mcmaster-Carr calls this a "Rod Clevis with Pin" and I am sceptical of anyone who would argue the rod end is a shackle.
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That being said, does that make a spigot a clevis?
 
Well, in my world, this has always been a clevis. But that doesn't stop the current employer from publishing internal documents calling a clevis pin a "detent pin". And then a shackle is a shackle.
 

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I've been paged, but it's the first day. Now I'm confused.
This started out in rigging, but somewhere along the way this was moved to become the QOTD.
 
Since Bill gave a real response I'll repost my original answer before I rethought the QotD rules:

My understanding is that clevis is a more generic engineering term for a load bearing element where the load is inserted within the device and then secured with a pin of some type. A shackle is a specific tool made for rigging. I also feel like the straight walls of the clevis that are designed for some amount of rubbing against the load are an important element of a clevis that generally you don't want on a shackle.

Mcmaster-Carr calls this a "Rod Clevis with Pin" and I am sceptical of anyone who would argue the rod end is a shackle.
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That being said, does that make a spigot a clevis?
Perhaps not but possibly a spigot is a faucet or a tap??
Next we could delve into root words and learn if there are any connections between clevises and cleavage.
Perhaps we could use a clevis to cleave between two spigots?
Toodleoo!
Ron Hebbard.
 
I tend to like Bill's answer, that a shackle is a clevis but not all clevises are shackles. you'll tend to find that most non-shackle clevises are designed for linear loading along their major axis. That's not to say there are not shackles that are also only designed for linear loads.
 
I thought this was rigging. If I answered QOD I apologize.

No worries, Ron had asked me to post this on QoTD but I had asked for a definitive answer first. Turns out that wasnt as clear cut as we thought, so it was posted in rigging. Eventually, we moved it over to QoTD, but more.for discussion reasons.
 
If you Google "shackle" and "clevis" and select "images", I think the difference is graphically clear. Whether a clevis is a bent flat bar around a board secured with a pin, two parallel "tangs" or plates with a pin, or a shackle like design at the end of a threaded rod - a clevis end on a turnbuckle - it seems clear. Maybe wishy washy but a clevis seems to be used for attachment, and a shackle is simply a connector or link. Clevises are used in tension and compression, shackles seem only useful in tension. And while a shackle may "bend" a little, a clevis may purposefully be designed to pivot at the pin.

At least in the good old US of A. North of the border all bets are off.
 
In my industry, high voltage substations, we use clevis (not sure what the plural is, clevi?) and shackles for transmission line hardware. Comparing the hardware we use, I would say the a clevis has parallel "arms", where as a shackle has rounded "arms". See this page. Then there's also a Y-clevis...

IMO (I'm electrical, not civil/strucural/mechanical), a clevis would be used for inline forces only, where as a shackle would be more tolerant of off angle forces, as others have said above.

 
I didn't feel like getting up in the middle of the night to shoot this so I waited til this morning.

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We just call it a hookup for our tractor but I guess it has a real name 'clevis'. For those interested this is our spreader hookup. The ridden wagons and hay wagons have the same hookup as well.
 
I thought Clevis was just another term for 'decolletage'.

:dance:
 
In my industry, high voltage substations, we use clevis (not sure what the plural is, clevi?) and shackles for transmission line hardware. Comparing the hardware we use, I would say the a clevis has parallel "arms", where as a shackle has rounded "arms". See this page. Then there's also a Y-clevis...

IMO (I'm electrical, not civil/strucural/mechanical), a clevis would be used for inline forces only, where as a shackle would be more tolerant of off angle forces, as others have said above.

In your diagram, everything with the name "clevis" has an anchor point. I still think more than inline or off angle that compression and tension is more important. A shackle would never have a compressive force, and never be anchored to a pole or structure. Those clevises and "ball" devices re very specific to your trade - ball and socket insulators.
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