A/V Geeks 16mm Films: Wire Rope Maintenance & Inspection (1970s Instructional Film)

Which is the most important part of a fishing rig? The hook or the line? Or is it the pole? In reality, each depends heavily on the other. The hook is useless without the line, and the pole improves the performance of both. In much the same manner, this big machine's function is to hold and maneuver the wire rope, which makes it possible for the device at the end to do its job, to work. But the rope is the real worker. For ropes work just as strenuously, just as complexly, as the many other precision parts that make up a shovel, or a crane, or other material moving device. Ropes such as this one work constantly when a machine is in operation, as individual wires and strands move and adjust under the load. On standing ropes such as this, evidence of impending failure may be difficult to detect, and their seeming inactivity tends to make machine operators perhaps a little less alert to potential trouble. In a broad sense, the machine operator's main concern lies with the other ropes on his machine, the so-called working ropes. These are the star performers, since they are the ropes that actually move materials and add value to materials being moved. For an industry, value is added to most materials in just two ways, by changing shape, size, or form, and by moving the material closer to where it's needed or wanted. Only wire ropes can economically move many products to where they're needed. Out of deep pits, across long distances of rough terrain, up to great heights, big lifts made infrequently, repetitive lifting of both small and heavy loads, all these wire ropes add value to products of commerce and industry. Thus, the longer a rope can be kept working within the limits of good practice, the more value that rope can contribute to its user, which makes it important to accomplish two things wherever ropes are used. One, keep ropes operating as long as possible. Two, keep records on the amount of work the rope performs, for it is only by measuring work performed that a rope's contribution, the value it adds, can be measured. Obviously, these factors, length of service and amount of work done, are related, yet length of service may not be as important in some situations as the amount of work accomplished in a brief time. On some big lifting assignments, a rope produces an economically acceptable output of work in a very brief span of time, while in other operations, maximum tonnage must be moved over a maximum span of uninterrupted working time in order to balance payout with initial cost. Probably the most significant factor in this evaluation of a rope is, machines use rope at different rates. Every type of work or work assignment, practically every type of machine, can be expected to use up its ropes at a different rate. The variables involved are virtually endless, ranging from the hands of the machine operator, to the design of drums and shivs, to the nature of the load. It is not unusual for one operator to move far greater tonnage during the life of a rope than a second man on an identical machine under comparable conditions. And of course, the variations between performance of ropes on identical machines doing different assignments can be even more spectacular. Thus, a continuing inspection program to evaluate performance and condition is essential if ropes are to deliver the maximum amount of work, or to make their maximum contribution to value and productivity. Every rope should be inspected at regular intervals throughout its useful life. So how do we inspect a rope? As a starting point, all ropes may be divided into two categories for inspection purposes. First, standing ropes, which are primarily supporting elements found on machines, on towers, and similar applications. The second category is moving ropes, those used to move loads, either up and down or laterally. Let's look at the so-called standing ropes first. When you observe closely an eye in the end of a rope, as it is alternately tightened and relaxed, the constant adjusting of strands and wires is apparent in the splice. What is not so apparent is that a typical spelted socket, or a swaged end fitting, is subjected to similar stresses under similar conditions. Careful examination of the standing ropes should be a part of every regular machine-wide fitness inspection. Wires at end attachments are vulnerable to metal fatigue from the constant vibration of working, since individual wires of the rope are not free to adjust at the end. Spelted end fittings are attached by brooming the end of the rope and pouring molten zinc around it, firmly wedging the rope in a cone-shaped socket. When you inspect such a socket, examine the rope for signs of corrosion where it enters the socket. But most important, examine the rope carefully for broken wires. Broken wires at the end fitting are the result of metal fatigue caused by vibration. But don't confine your fitness examination only to the ends of standing ropes. Inspect them carefully end-to-end to detect broken wires, for metal fatigue can also cause broken wires anywhere along the length of a rope. And of course, examine all pins and fittings for excess wear or signs of breakage. When examination of a standing rope has been completed, and you're satisfied it still measures up to the applicable standards, remember that you are dealing with a working machine. Put on the prescribed lubricant so that all those wires and strands can continue to move and adjust freely, and the rope is afforded some protection from dirt and corrosion. Once you've examined the standing ropes, turn your attention next to the shivs and drums, for virtually every machine that uses wire rope has shivs and drums. Both must be considered part of the rope system, since their performance has a direct bearing on rope performance. Properly grooved shivs and drums carry the rope comfortably in the bottom of the groove, without excess side room or play, or without pinching the rope. As a general rule, drum and shiv grooves should provide support for 135 to 150 degrees of the rope circumference. One of the most important wear points on a shiv or drum is of course the bottom of the groove. Ideally the groove should be smooth, so strands can move and adjust as the rope works. When the groove becomes corrugated or imprinted with the rope's pattern, it can damage even a new rope, and will not permit any rope to move and adjust freely. A worn out shiv or drum should be replaced, just as any other worn out part should be replaced. Each shiv and drum should be inspected routinely for groove wear, as well as for general condition and soundness. Cracks, pieces broken out of sides, sloppy or badly worn shiv bearings, all affect performance of the shivs and drums, and the ropes that move on them. When you've determined the support system for your materials moving machine meets your applicable standards, turn your attention to the star performers, the wire ropes that actually carry the load. The inspection criteria for wire ropes vary from machine to machine, and are published in regulations and standards such as these. What applies on a construction project may not apply in a well drilling operation. What applies to mining machines may not apply to maritime applications. It is important for each wire rope user to be aware of the inspection criteria which apply to his industry and equipment. As a general rule, all industries have operating standards which recognize that wire rope is used up when it is used. The rope literally loses work capability over its working life. Inspection criteria establish benchmarks to help you determine when a rope must be replaced. The basic inspection criteria are, one, evidence of metal loss due to abrasion from normal rope movement or abrasion from foreign objects. Two, evidence that wires on the surface of the rope have been hammered or the rope crushed, usually by contact with other parts of the rope when wound on the drum. Three, most inspection procedures involve measuring the rope's diameter, which is always the largest dimension across a rope. Four, elongation of the lay of the rope, an indication that a rope may have been overloaded or is breaking up on the inside. Five, the frequency at which wires are breaking in a given length of rope. These five rope inspection points form the basis for evaluating a rope. The first three, metal loss, metal deformation, and reduction in diameter, are fairly simple observations which anyone can make. The latter two, lengthening of lay and broken wires, require special skill and training and observation. So let's discuss them. To measure the length of lay, simply place a sheet of blank paper and a sheet of carbon paper on the rope. Hold tightly and stroke with the side of a pencil so the rope's print is made on the paper. On a six-strand rope, make a mark through the print of one strand, and then a similar mark where this same strand print is repeated. This is one rope lay. A carbon print showing three or four continuous length of lay will provide a measurement which may be averaged to determine the length of one rope lay. By comparing the length of lay at regular time intervals in the life of a rope, any sudden change of the length can be detected. Such a change may indicate internal breakdown of the rope or abnormal rope rotation. Broken wires are probably the most important single indicator of rope condition, and inspectors must be especially alert to the number of broken wires within the span of one rope lay. When inspecting for broken wires, make sure the surface of the rope is clean enough to see any broken wires. At points where broken wires are found, mark off with string or chalk one rope lay as previously described, and count the broken wires visible in one rope lay. The number of broken wires permitted per rope lay, both in a single strand and in all strands, is specified in your standards and regulations. For inspection purposes, the number of broken wires per lay, as indicated by your industry standards, is the important factor. Another form of rope damage for which rope users must be especially alert is evidence of abuse. Abuse is probably the most common form of damage found on working ropes. Abuse is often seen in kinks, such as this one, which prevents wires and strands from moving and adjusting in the rope. Abuse often results in external damage like this. Damage from abuse is usually easy to detect, and is the type of wear for which all who work around ropes should be constantly alert, for abuse can occur anytime. But in the long run, the best operating practice is that which helps get longer service out of wire ropes, which results in greater machine productivity. Many operators have found that a combination of frequent, conscientious, and thorough inspections, coupled with records which show how much work a rope has done, results in greater value received on the purchase price of the rope. Records showing material moved are the best means for measuring how much work a rope has delivered. Many operators of machines that do the same type of work day after day, remove ropes after an economically worthwhile amount of load has been moved, then literally take apart sections removed from the most worn areas along the length. Internal examination and actual tensile test for strength may indicate the rope still holds useful life. If this is the case, the next rope on the machine can then be operated for a longer period, made to move a greater amount of material before being taken off, then again opened up and examined. In this manner, experience can be built up over a period of time to establish a fairly predictable, useful work life, or tonnage moved capability for a particular rope in a specific type of work or machine. For when the final tally is run on any job, the important factor is the movement of product or material at an increase of value. Careful inspection at regular intervals, coupled with production records that show how much work a wire rope has done, will make it unnecessary to decide whether the pole, the line, or the hook is the most important. The most important thing is the catch, the work done, which is why the serious fisherman, who knows more big ones are lost than get away, changes his line before it spoils the day, or the trip.