Posted By Stuff4blokes Andrew, no experience of these specific trucks other than seeing them working. However, it seems to me that if you follow your normal incident investigation process to establish what actually happened, how and why then you should be able to determine whether it was a genuine 1-off incident or could be repeated. The solution should then become more easy to work out. If necessary involve the suppliers and maintainers of the equipment but remember that they will have their own agenda, particularly if there is any injury or loss involved! Don't let them fob you off with "it's a software problem".

Posted By ANDREW GEELAN Hi Thanks for the reply, the investigation showed this was not a one off incident, however the manufactures are trying to blame both software and operator error. I will keep on their case

Posted By Peter Still Paul, The standards numbers you're looking for for safety-related systems are BS EN 62061, BS EN ISO 13849-1, or BS EN 61508! Peter

Posted By Peter Still Paul, Of course, I agree with your comments, BUT... we don't know enough about the incedent to comment. For example, was the software that has been blamed for contributing to the incident configured by the user of the FLT, or had it been subject to a modification, or was it as written by the FLT manufacturer, or the control system supplier, or are we talking about a firmware fault in a programmable controller. Certainly shouldn't have happened though, and the standards mentioned include the sort of verification procedures you describe. Peter

Posted By D. Hilton Why jump to the conclusion that this incident relates to "safety critical" equipment. Without additional information from Andrew, the "failure" could be a slight increase in clamp pressure causing an out of spec diameter or damage to the outer layers of the rolled paper. Similarly, the system in use could have a number of clamp pressure settings allowing the operator to select the nearest acceptable setting relative to the materials being handled. Also, there are a number of factors that could also have contributed, i.e. clamp sensor, pneumatic/electronic control unit, pneumatic, hydraulic valve. etc.

Posted By D. Hilton Paul Andrew did not refer to the term accident. He did however use the term failure and incident.

Posted By D. Hilton Paul, the failure of the controls in such cases results in out of spec and outer layer damage to paper and do not present the potential for injury. There are no "latch" pins or similar devices. The function of an ICS is to reduce pressure to prevent product damage only and so it is not a safety critical control system. With regard to the dropping of paper rolls this is prevented by means of cylinder check valve ensuring positive pressure at the clamp in the event of a loss of supply pressure.

Posted By Paul Skyrme D. Hilton, I simply "created" the example of a latch pin to illustrate my point. I have seen the reel handlers which are being referred to, but not up close and have not worked with them. However, I have worked on all sorts of control systems from repair through to programming design etc. I was trying to illustrate that some things which are seemingly unconnected can have an impact on safety and trying to plant ideas to assist in the identifications of the root cause of the issue. As I said, I had mistakenly read "accident" not incident! Paul

Posted By Paul Skyrme D. Hilton Just re-read your post. Note to self, read carefully prior to posting! Excuse me I'm at home recovering from an op today. Would you not then agree that the cylinder & the check valve are safety related items? This was the sort of point I was trying to make. I would suspect then that the check valve is built in to the body of the cylinder, no pipes to fail between the cylinder and the valve. Also that this is pilot operated to allow the clamps to release else the oil/pressure would be locked in for ever. The control for this pilot operation should also surely form part of the safety related part of the control system? this could be a hydraulic valve operated by hydraulics, air, electrics via a computer etc. could it not? It is almost certainly linked to the reel release system, so that it can only be opened when it is safe to release the reel? We must not simply think of control systems in the manner of computers and software. Hardware items form part of control systems too. You have there stated that the reel is prevented from falling by a hydraulic system, thus the control to prevent the reel falling is a hydraulic one. Yes? Paul

Posted By Paul Skyrme Hi, I'm not trying to contradict an other posts. My first post related to software as in Andrews reply to previous posts software was brought up, hence why I responded to a software based query. This post of mine however does go on to state software and systems. Peter then went on to mention some discrete areas of control systems where software "errors" could be experienced. I then went on to suggest that seemingly innocent software can have other implications. I still think that a failure in the control system could release the roll. One has to be careful in the definition of failure and the affects of compound failures. An electrical short circuit, or a failure elsewhere in a control system could activate a solenoid valve unintentionally could it not? This could result in the unintentional operation of the piloted check valve, thus opening the clamp cylinder to tank and allowing the fluid pressure to dissipate. By your description the only thing then holding the reel would be the spring? Would this be strong enough to prevent release of the reel whilst being transported? Springs break too! Especially if overloaded. Paul.

Posted By Paul Skyrme Hi, It seems wrong to keep typing D. Hilton and I don't know your name sorry. No I think we AGREE! The solenoid coil component going open circuit will not open the check valve. We agree. The solenoid operated valve jamming in the closed flow position will result in not opening the check valve. My point is having actually worked on these types of hydraulic systems for a manufacturer of this type equipment and similar, in a repair, diagnostic and applications engineering type roles, I do understand your points and those of the other posters intimately. Well to be honest I hope so,as one of my control concepts for a retrofit to improve the controls safety, repeatability and accuracy of a major hydraulic system which is operating on a major public protection civil engineering project in the South East of England! The check valve is held closed by a spring, and the back pressure of the hydraulic system generated by the load. It is difficult for the load to be released unless the cylinder seals fail and allow the oil out of the other end of the cylinder (which may well also have a pilot check) or, a fault occurs elsewhere in the control system. Which is the point I was trying to make. If you apply an unintentional voltage to the correct solenoid without any other faults present, it will actuate and may open the check valve, it may well also actuate the cylinder to release the roll. Trust me I have done it on very similar systems in the event of faults under controlled conditions to mitigate other hazards. If the valve does not simultaneously have an actuated opposing solenoid then it should move. You can bypass the control system for the solenoid valve and put the control voltage straight on to the solenoid coil, this would operate the cylinder in the reverse direction, opening the clamps. This would release the roll. I took the spring to which you referred to be part of the clamp mechanics closing the roll jaws on to the roll. This medium of communication can be very prone to misunderstandings can't it! The fault elsewhere in the control system is the point I was trying to make. Taken in isolation the reel jaws are almost certainly very safe. The hydraulic clamp cannot be released without a definite command from the "truck" telling the jaws to open. My point was that that command could be generated by a fault condition. I've seen it for real on similar systems and had to investigate and resolve such issues through to root cause. Please don't take my posts as offensive or trying to contradict, I enjoy debate! Sorry! Also, my background before getting more involved in H&S is control systems engineering on industrial machinery from mechanical through pneumatics, hydraulics, (I have taught Hyd & Pneu) electrical, electronics, and programmable systems. I've undertaken fault finding and repairs, maintenance, applications engineering and design of these types of systems for machine manufacturers, in house maintenance and engineering departments for our own equipment and that bought in, and for electrical, electronic, pneumatic and hydraulic control systems manufacturers. My specialities have been root cause failure analysis, predictive maintenance and the retrofitting of engineered solutions from concept, through design to implementation. I now do this for myself. My relationship to H&S is that PUWER98 (& other legislation, previous and current) has a big impact on engineered solutions these days, hence my membership of IOSH as well as my engineering institute! Please let the discussions continue in a friendly manner. IF anyone wants to. Perhaps Andrew could give some more non "classified" info which could assist him in getting to the root cause of the problem and even provide information to other users of such equipment on the forum to ensure that these things are ironed out and we all work in safer environments. Paul.

Posted By Paul Skyrme Andrew, As far as PM's go, ensure that the FLT's & clamps are maintained to manuf' specs. If the FLT's are on hire/lease ensure that the visiting maint guys do the PM's. It is in the hire/lease co interest to do the minimum on a cost basis. That is not to say it would happen, but, it could. One thing, not knowing exactly what the failure was as I have stated. I would check that if the clamp is powered by the FLT hydraulic system that the fluids are fully compatible. I have come across a system previously where the original specification of oil was ignored, and an "equivalent" added. Eventually this caused significant problems with the systems. Thankfully NOT safety related, but... Paul