I had a trainee out with me last week from the local adult education college. He asked me if it was really true that load straps are weaker when they are twisted, as this is what he had been taught at college. Apparently the police here are also of the opinion that twisted straps are weaker. He couldn’t see how it could be true though, and neither can I.
As far as I can see the load through the cross-sectional area of the strap is the same, and twisting shouldn’t cause any stress points that I can figure out.
Also, I’ve found that on open trailers at least one twist where the strap is not actually against the cargo is essential to stop them vibrating.
Good question, is it due to the fact you are putting “tearing” forces across the face of the strap when it is twisted and then it could fail when tightened?
As howatsi insinuated the positioning of the forces on the strap could be altered when it’s twisted so I would say that it’s quite possible that a twisted strap could be weaker than a flat one.
For instance imagine a strap with several twists in it making the pulling force act on an edge of the strap rather than across the entire width of the strap.
I would say that it’s not likely that a single twist in a strap would significantly weaken it but with several twists it could possibly be weakened to a significant degree.
At the end of the day you should try to avoid twists in straps because it’s not the way they’re designed to be used, not to mention the fact that it doesn’t look good.
Having said that I could be talking a load of [zb]
The german police and Bag will point out that twisted straps are a No No, also that all straps must still have their blue tag fitted ,and no frays or rips in them as this makes them no longer servicable , and you will get told to change them and possible a fixed penalty and points will be awarded if they belive it is a effecting the lashing of the load,
I had a trainee out with me last week from the local adult education college. He asked me if it was really true that load straps are weaker when they are twisted, as this is what he had been taught at college. Apparently the police here are also of the opinion that twisted straps are weaker. He couldn’t see how it could be true though, and neither can I.
As far as I can see the load through the cross-sectional area of the strap is the same, and twisting shouldn’t cause any stress points that I can figure out.
Also, I’ve found that on open trailers at least one twist where the strap is not actually against the cargo is essential to stop them vibrating.
Does anyone have any thoughts about this?
Thanks!
Personally I would go with the one twist as I think that a vibrating strap is far more likely to fail, or become loose. After all vibration is just another word for ‘shaking to bits’!
Does it really cause a shearing force though, if they are twisted? Of course, part of the tension would act in a direction to try to un-twist the strap, but at each individual point along the strap the force is still acting in the direction it would if the strap were not twisted.
If I remember tomorrow I’ll look at the blue tags on mine, see if I can get a web address of the manufacturer and email them to ask if they’ve done any testing.
Of course, actual facts are irrelevant anyway, if the police have already decided that straps are weaker that way. After all, it’s their version of reality we have to work with
Thanks for the comments so far, interesting food for thought!
bubsy06:
You should see the straps we are expected to use to hold 33 cages in place
Some are tied back together in about 4 places where they have snapped
That is only the fault of a driver, any broken or damaged ratchets or straps should be thrown straight in the skip and replaced before you leave the depot
Wheel Nut:
That is only the fault of a driver, any broken or damaged ratchets or straps should be thrown straight in the skip and replaced before you leave the depot
How is it my fault■■?
I ask for new straps and never get any so have to make do with what is in the trucks. Am I supposed to pay for them out of my own pocket don’t ■■■■■■■ think so.
Wheel Nut:
That is only the fault of a driver, any broken or damaged ratchets or straps should be thrown straight in the skip and replaced before you leave the depot
How is it my fault■■?
I ask for new straps and never get any so have to make do with what is in the trucks. Am I supposed to pay for them out of my own pocket don’t [zb] think so.
No you’re supposed to be aware that it’s YOUR responsibility to see that the load is secure! The comeback will be on you…
44 Tonne Ton:
No you’re supposed to be aware that it’s YOUR responsibility to see that the load is secure! The comeback will be on you…
Which I do by stacking the cages in a way that most of the wheels are facing towards the side of the lorry and not the back and also by using the bolt on the tail-lift/back door. If there is another dodgy strap in the truck I will use 2. Not had any come loose yet.
Wheel Nut:
That is only the fault of a driver, any broken or damaged ratchets or straps should be thrown straight in the skip and replaced before you leave the depot
How is it my fault■■?
I ask for new straps and never get any so have to make do with what is in the trucks. Am I supposed to pay for them out of my own pocket don’t [zb] think so.
No one is saying you have to pay for them, you don’t pay for fuel or repairs do you?
I’ve never liked going for that last extra click of the ratchet if the strap is twisted. I can’t state any facts but I’ve always thought a twisted strap is weaker. That’s just my own personal opinion
Personally I would go with the one twist as I think that a vibrating strap is far more likely to fail, or become loose. After all vibration is just another word for ‘shaking to bits’!
[/quote]
I agree, I see some AW Jenkinson bulker drivers put only 1 twist in their straps, stops vibration but still does it’s job. any more twists? NO!!
I use straps and put only a single twist in. How would you like to drive for hours with BBBBBBBBBBBBBBBBBBBBBBRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRR coming into the cab■■?
Goldfinger:
Personally I would go with the one twist as I think that a vibrating strap is far more likely to fail, or become loose. After all vibration is just another word for ‘shaking to bits’!
I agree, I see some AW Jenkinson bulker drivers put only 1 twist in their straps, stops vibration but still does it’s job. any more twists? NO!!
I use straps and put only a single twist in. How would you like to drive for hours with BBBBBBBBBBBBBBBBBBBBBBRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRR coming into the cab■■?
[/quote]
Just like a reefer?
If they were designed and tested to be used in a specific way then that is probably the way they should be used
Any deviation from that way and they are not likely to perform 100% as intended
Also, if you lose part of your load on a bend and the police notice that the rest of your straps are twisted then they could decide to try and shaft you with some C&U Reg? All depends if you interupted PC Angus Nairn in the middle of his roll’ sausage n’ tattie scone that morning
Not sure about “weaker” but they are certainly more loaded, as the deformation adds stress. It also causes the load to distribute differently, particularly into shear, as pointed out before. The straps were designed to resist tension, they are not great in shear (and rubbish in bending, torsion and compression; that’s why you can wind, twist and crumple them, they deform easily).
As of the weakness, it’s difficult to say, the cross section are stays the same but moment of inertia and section modulus change, so twisted straps respond to load differently (also vibrate differently, as observed). Extreme case would be to twist the strap so that it would form a tube, but not perfect as it would have a helical split all along… You can ask your traineee to do the math I’m too lazy tonight
Wheel Nut:
That is only the fault of a driver, any broken or damaged ratchets or straps should be thrown straight in the skip and replaced before you leave the depot
How is it my fault■■?
I ask for new straps and never get any so have to make do with what is in the trucks. Am I supposed to pay for them out of my own pocket don’t [zb] think so.
No you’re supposed to be aware that it’s YOUR responsibility to see that the load is secure! The comeback will be on you…
What 44 Tonne and Wheelnut said, and in more ways than one.
If you are knowingly using defective equipment, and the cages come loose and injure you or someone else, you as the individual may be held liable for the other bloke, and the insurance could well claim that you contributed in part to his and your injuries via your negligence.
This happened at one of our mills. A bulk tipper driver had been using a strap to pull his sheet back, which was knotted in several places. One of them gave way, driver fell back and broke his arm. No compensation.
If you’re not happy with the load restraints, tell them you’ll refuse to take it out till they sort it. If they won’t, they’re not worth working for anyway. I know it ain’t that easy mate if you’ve got a family to feed, but you won’t be feeding them from a hospital bed either will you?
don’t ■■■■■■■ think so.
I’m too lazy tonight