Lifting strap with buckle to alternate between two lengths

[ckb614]

Is there a type of buckle for lifting straps that allows you to fold a section of the buck over to shorten the length of the loop? And then you can disengage the buckle easily to return the loop to its full length?

Let me know if I can clarify. Thanks

 

[dhengr]

You most certainly could clarify. Whether you can or not is all up to you.

There’s Euler buckling, there’s the she/he buckled under the pressure type buckling, there’s the one-two buckle your shoe type, on and on...

 

[ckb614]

Nevermind

 

[zeusfaber]

Are you trying to describe something that works like one of those metal watch straps?

A.

 

[ckb614]

No. It would be something that essentially fold over a small section of the strap to reduce its length and add tension.

I should post pictures, but to demonstrate: if you put one finger under a strap and one finger above offset by say 2 inches, then lift the finger on the underside to wrap the strap around the top finger. So you would fold the strap over and take 4 inches out of the overall length

 

[dhengr]

Ckb614:
“Nevermind” (spelling?) is not good enough, here, and it doesn’t reflect well on you. My intention was to kick you in the butt, and make you think. We can’t see what you’re thinking or read your mind from here. So now, Good for you..., at least you’re thinking now. Maybe a sketch would be worth a thousand words though. If you are an engineering professional, you have to be able to explain your problem and situation to others, with no ambiguities . If you are not an engineering professional, you should read the posting rules here on Eng-Tips, and you should probably not be here.

Your latest description prompts this... and I thought about this then, but couldn’t resist the kicking, to wake you up, de-lazy you. Take two round bars 1/4 - 3/8" dia., spaced 2" apart, and just a little longer than the lifting strap is wide, and held apart with two side bars, maybe 3/4" wide by 3.5" long, riveted or with threaded ends and nuts or some such. The strap is threaded through the round bars in an ‘S’ shaped fashion. One of the side bars has a 12" long extension (handle) on it. If you rotate this handle 180° and then hold it exactly in line with the strap, you will take up 2" of strap length, a 360° handle rotation is 4" of strap length up-take, etc. But be careful, if you do not hold the handle exactly in line with the strap, the torque on the handle might break your wrist.

The exact sizes, dimensions, forces and torques are for you to diagram, sketch and figure out. But, the up-shoot is that you must describe your problem so there can be no second guessing about what you mean. I think I have done that above, but maybe not. This is always a difficult problem if we are not sitting face to face and being able to instantly sketch and see facial expressions, etc. You should be able to read my description and basically draw only one sketch of what I intend. The description can not lead to two or three different sketches or you leave people guessing at what you mean. So, always reread your own description and be confident that only one sketch can be drawn, or you leave people guessing at what you mean.

 

[ckb614]

I think you may need a lesson or two on responding to questions without being snarky. I fail to see how there is ambiguity in the word "buckle" when I'm talking about lifting straps. If asking for advice on this forum means dealing with people like you, then it's not worth my time.

 

[zeusfaber]

I think you may need a lesson or two on responding to questions without being snarky.

That kind of suggests that you haven't read dhengr's other nine-hundred-odd helpful and well constructed replies to questions on this forum. All the evidence I see points to the problem being elsewhere.

Would it help if you explained what you mean when you say "lifting strap"? I don't see many buckles on the webbing on your everyday rigging warrant - so we might be at completely cross-purposes.

Perhaps you're trying to describe a mechanism like this one:

http://www.apvalves.com/uk/graphics/manuals/BK3 Fitting Instructions.pdf

- in which case, there is something like it, but maybe not used for lifting straps.

A.

 

[cloa]

I did find dhengr response unreasonable- if he said here is the rigging list of knot and joints (see how many there are) then that is reasonable but saying Euler buckling et al. when that is clearly excluded is rediculous.

 

[rb1957]

how about attaching three loading eyes to the strap (instead of the obvious two) ?

 

[racookpe1978]

I recommend "No, don't do it." At least NOT with a buckle-type fitting.

You'd take the strap (wide, uniform material certified, inspected, approved for lifting) and put ALL the force not on the wide (flat) web but on one point of one part of the web's fabric around a stress-riser (the hole) with ALL of the load coming into one point on the buckle "clip" where it touches the "lock" steel-to-steel.

 

[rb1957]

?

i imagine the buckle is sewed into the strap webbing with a load ring, so the point contact in metal-to-metal and the load into the strap is distributed, no?