nitros44
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Post by nitros44 on Feb 6, 2012 21:41:31 GMT
Not a horror story as such but i keep being asked what does the extreme end mean of a coil spring?? ;)and how to assess the spring. In the photographs the NSR coil spring was found incomplete The OSR coil spring was found in tact no problems. One of my colleagues at work today said if i made a decision to fail the NSR coil spring i would be incorrect, As the manual only says extreme end and there is no limits to regard measurements,i just want to to throw the debate open to members to find out how they would come to a conclusion to either pass/advise,abandoned or fail the defective coil spring The pictures are taken with the suspension hanging free and when the suspension was dropped back down the spring did not need any assistance to locate it, Attachments:
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nitros44
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Post by nitros44 on Feb 6, 2012 21:44:14 GMT
NEARSIDE REAR COIL SPRING Attachments:
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nitros44
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Post by nitros44 on Feb 6, 2012 21:45:12 GMT
NEARSIDE REAR COIL SPRING Attachments:
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nitros44
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Post by nitros44 on Feb 6, 2012 21:46:24 GMT
OFFSIDE REAR COIL SPRING Attachments:
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nitros44
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Post by nitros44 on Feb 6, 2012 21:48:00 GMT
NEARSIDE REAR COIL SPRING FROM DIFFERENT ANGLE Attachments:
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nitros44
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Post by nitros44 on Feb 6, 2012 21:51:17 GMT
NEARSIDE COIL SPRING SUSPENSION HANGING FREE Attachments:
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phaetonott
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Post by phaetonott on Feb 6, 2012 22:44:28 GMT
I failed one on a Transporter the other day, that was broken at one end, with the broken bit still there and likely to fall out. The other side had been broken for a while, at the top and the customer wisely decided to change both, even though I had only advised the second.
When stripped the "advised" one had cut into the spring pan because it no longer sat on the reinforced area of it's pan.
Having seen that I would have been happier if I had failed both,
Would that spring "correctly locate" by wrapping snugly around the boss in the centre of the spring pan? If so, that spring fails for not being correctly located.
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nitros44
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Post by nitros44 on Feb 6, 2012 23:17:59 GMT
I failed one on a Transporter the other day, that was broken at one end, with the broken bit still there and likely to fall out. The other side had been broken for a while, at the top and the customer wisely decided to change both, even though I had only advised the second. When stripped the "advised" one had cut into the spring pan because it no longer sat on the reinforced area of it's pan. Having seen that I would have been happier if I had failed both, Would that spring "correctly locate" by wrapping snugly around the boss in the centre of the spring pan? If so, that spring fails for not being correctly located. Part of the requirement is for the coil spring to correctly locate,which it has,even with a section missing.
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Post by baz657 on Feb 7, 2012 16:08:46 GMT
The way it has been explained to me is to check if the spring is movable (twistable?) with the suspension fully hanging. If it doesn't move it's deemed to be located correctly and conversely if you are able to rattle it around it wont be correctly located. Do I have any problems with this? Well, yes and no These examples assume that springs are located correctly but with pieces missing.... Example 1 - Ford Ka rear spring broken at top. It won't be going anywhere, it doesn't rattle and no chance of it "escaping" and causing damage to tyre/brake pipes, etc. No problem there so just advise... Example 2 - 2000MY Ford Mondeo front spring broken at the bottom. By pure chance it has broken at a point where the spring doesn't slip over the lower cup and into the tyre/brake pipe, etc., but it must be weakened for it to snap in the first place. I've seen plenty of these that have gone through both tyres and brake hoses. Problem there so it would get a dangerous advisory (it's my opinion so I'll state it). Example 3 - the spring pictured above. By the new definition, it's a pass and advise but I think I'd tag a dangerous onto it. There again, I might even fail it using 2.4.C.1.b... . I'd argue that wear and/or corrosion caused the fracture in the first place. So while thinking about it and typing this, I've come to the conclusion that unless a spring is broken and the break is clean and at a right angle, it'll fail for the reduction in cross sectional area. If the broken piece was cut off would the spring still "locate"? Irrevelant to me because I test as presented. Have I opened a can of worms here?
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Post by aylesburyjock on Feb 7, 2012 17:13:49 GMT
I think you have baz, because you have just stated that the instruction in the inspection manual is irrelevant to you testing. How can that be? When you jack the vehcle up so the suspension is hanging free, what is irrelevant is whether the spring is rattling around or not at that point, as long as it locates properly when the suspension is lowered. Since few breaks in springs are at right angles, there is usually going to be a thin 'tail', but failing it for being thin due to wear or corrosion is an attempt to get round the relaxation of the fail criteria and do things your way, instead of VOSA's. That broken bit won't show any wear and not much more than surface corrosion come appeal time when you have a customer who is fonder of his money than his life. Accept that things have changed and test as instructed would be my free advice.
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Post by baz657 on Feb 7, 2012 17:26:38 GMT
I think you have baz, because you have just stated that the instruction in the inspection manual is irrelevant to you testing. How can that be? Sorry for the confusion Jock - what I meant by irrelevant was it wouldn't be a decision based on what "might be" if the spring was neatly cut and presented for test in that state. I would have to base my decision on what was actually in front of me at the time of test - a coil spring with a reduction in cross sectional area. My interpretation of the manual is what can lead to trouble if it's different to my local VE. There is no reference in the manual to any acceptable tapered end be it by design or due to a fracture. What started simply as a train of thought turned into an overnight express!
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Post by excessive on Feb 7, 2012 20:36:46 GMT
I personally would fail the one as pictured, the guide is a little contentious from what is posted in the information to what is posted under the rfr.
As nitros pointed out, the spring does sit correctly even though it's missing more than a complete coil.
However in such circumstances I would use the very definition of the word extreme to base an opinion.
The spring is clearly missing a substantial amount from what was its original state. In other words it's incomplete way past what would be considered the extreme end.
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Daveg
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Post by Daveg on Feb 7, 2012 20:39:02 GMT
Coil springs fractured and incomplete Fractured to me is a piece missing, and incomplete is in two halves, both halves being present at time of test Spring fractured and the spring seat. A spring normally fractures at one of it's extreme ends, the corrosion present sometimes looks like it's been there for quite a while, while other times the corrosion is very light, even showing clean metal on some occassions. VOSA's idea is that where a spring is either incomplete or fractured when the vehicle is jacked up and the suspension hangs free, will the suspension spring locate back onto the spring seat without manual help, if so it is a pass and advise. I think reading the threads here, the problem seems to be whether the springs cross sectional area has reduced, or whether the spring end is correctly located on or in the spring seat? Taking each in turn;CSA - Cross sectional area, this is not the fractured part of the spring, the cross sectional area is the diameter of the spring at it's thinnest point, so the easiest way to understand this is to go back to school , get some plastericine and roll into a circular tube of the same diameter, then hold at each end and gently pull progressively apart and watch what happens in the middle, you should see that the plastercine will start to thin out before it fractures, tensile testing , this is refered to as necking. In this new area of thinner diameter, which we call the area of necking, this is the new cross sectional area, which is not the same as a coil spring end being fractured, where the coil spring end in a fractured state has not lost it's cross sectional area of diameter, it is in fact the same diameter after the fracture as it was before the fracture Spring seat.Most spring seats have what is referred to as a buffer, the coil spring end normally is positioned so that the buffer prevents the spring from rotating in a circular path, although some spring movement is to be expected . A spring correctly located on or in a spring seat does not have to be fitted in accordance with the vehicle manufacturer recommendations for an mot minimum criteria , so long as the spring end, fractured or not is located onto or in the spring seat, at any position, so long as it is not likely to pierce through a tyre wall on lock to lock, then it is a pass and advise. Where a coil spring is likely to pierce a tyre like on some Renaults, i.e. the spring end is hanging over the spring seat likely to affect steering and braking, then this in my opinion is a fail marked dangerous. Anything else where the spring is fracured and or incomplete either sat into or on the spring seat at the time of test, unless you can actually prove that it is dangerous, and proof is real evidence, then again in my opinion it's a pass and advise. Dave Dave
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nitros44
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Post by nitros44 on Feb 7, 2012 22:46:29 GMT
The RFR INCOMPLETE COIL SPRING relates to a situation such as a coil spring were part of it has been deliberately cut off,normally done when someone wants to lower the suspension (to use as an example ),hence because part of it has been cut off, the coil spring has now become incomplete,the same would be said with a coil spring that had snapped in to 2 parts or whatever and the remaining parts of the spring are not present at time of test. To say a coil spring has fractured would mean its been forcibly separated in to 2 or more pieces,but to prove a coil spring is fractured you would need the other pieces present at time of test, to visually see that the coil spring has actually fractured ,
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Daveg
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Post by Daveg on Feb 8, 2012 10:34:06 GMT
I understand what you are saying in your first paragraph, and do agree, although I always thought about it slighly different because in a distance memory I am sure VI back in their day put some idea in my head slightly different, or the other way round In relation to the fracture itself, knowing that some people have been known to cut springs in the past, the appearance to me has always been too specific in that the part of the spring end that has, in my opinion, always appeared to be a fracure, has always been seperated from the spring end on a slant basis with a sharp edge , so I have always took that as the spring had fractured itself when in use on the road, rather than somebody cutting it . I could have as you point out above been getting things the wrong way round , the spring end being present but fractured is fractured, and the spring end fractured and missing is fractured if the end of the spring is not a clean cut Dave
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Post by aylesburyjock on Feb 8, 2012 21:31:08 GMT
I think you have baz, because you have just stated that the instruction in the inspection manual is irrelevant to you testing. How can that be? Sorry for the confusion Jock - what I meant by irrelevant was it wouldn't be a decision based on what "might be" if the spring was neatly cut and presented for test in that state. I would have to base my decision on what was actually in front of me at the time of test - a coil spring with a reduction in cross sectional area. My interpretation of the manual is what can lead to trouble if it's different to my local VE. There is no reference in the manual to any acceptable tapered end be it by design or due to a fracture. What started simply as a train of thought turned into an overnight express! My mistake Baz, that does make sense. ;D I can see there is going to be some confusion with this. How much is the extreme end? When the spring settles as the suspension is lowered does it just have to sit in the cup? Does the end have to locate against the buffer? Springs whose end coil fits snugly around a raised boss like clio rears where the end coil usually breaks off, the broken end cannot locate properly although the end of the spring will be sat on the spring seat. A little more guidance here couldn't hurt if VOSA is listening.
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nitros44
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Post by nitros44 on Feb 9, 2012 0:05:10 GMT
The word extreme has many defanitions,but the one i think VOSA are implying is one of the following;
THE UTMOST POINT,
EDGE ,
BORDER,
OUTERMOST,
UTMOST FURTHEST,
AT THE WIDEST LIMIT,
I ALWAYS UNDERSTOOD WHAT THE EXTREME END ON A COIL SPRING IS,,,, WOULD BE THE TIP OF THE COIL SPRING AT EITHER END
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Post by aylesburyjock on Feb 9, 2012 7:51:46 GMT
1mm? 1cm?1 inch?1 coil? We all know what we think 'extreme end' means, but that is only going to be, as Daveg is fond of saying, a personal opinion. VOSA need to clarify this one if they want everyone testing to one standard. That's the only problem, because we can all test to a safe standard, but with no clear defenition here we won't all be testing to the same standard.
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Post by excessive on Feb 9, 2012 10:10:11 GMT
There is a clear definition that extreme in reference to an edge or end is the utmost furthest or remote point. Bear in mind there is NOT a definition for the word excessive in the testing manual Folk need to decide for themselves if they want to factor a measurement into the equation, but it's not actually relevant. I will say though that testers should make them self comfortable with the correct definition of certain words - Unfortunately incorrect interpretation of a word is not going to stand up under scrutiny
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wally
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Post by wally on Feb 9, 2012 10:52:45 GMT
Unfortunately incorrect interpretation of a word is not going to stand up under scrutiny That is the big problem, whoever is putting that interpretation under scrutiny has to be able to define it clearly without doubt and make his/her views stand up to scrutiny. Otherwise it is just a matter of personal opinion and it is wrong in my view for somebody to have a rollicking for having a different opinion. If they want a common standard then they should clarify all uncertainties. Wally
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