• JustinReoff
• 09 Nov 2024
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Diagnosis of the Iron Heart

It was an unforgettable voyage. Properly speaking, for our hosts — the sailors of the refrigerator trawler Salghir — it was quite crdinary The distance was not too long — some 7,000 miles: we sailed from Sevasiopol to the African port of Walvis Bay. To them this was a routine affair. But for us...

Can the heart tell — each minute of each day — the story of how it wears out due to its continuous work? This is how the question to which we were supposed to provide an answer could perhaps be formulated True enough, we were interested in an iron heart — the diesel engine of a ship

Though our problem was not a medical one, scientists have long been using a medical term — "diagnosing" — in this case.

Our job aboard that trawler was to test a new diagnosing technique — a radioactive method involving the use of tracer atoms. Preliminary data suggested that it would be consi derably more effective than any previous procedure.

The guest on board the trawler cannot escape the traditional christening ceremony on crossing the equator (left). The voyage is over and back to the lab. At right, Leonid Polyakovsky discusses some of the results of his investigations with a colleague

In the past, engineers estimated the wear and tear on machine parts and units like doctor who does not know what an electrocardiogramme is and can judge the state of his "patient" only by opening his chest and inspecting his heart.

The marine diesel is a sophisticated structure with a host of constantly moving parts. The moment one of them goes even slightly out of order, the vessel's entire powerful heart is threatened by paralysis.

Assessing the wear on an engine requires taking it apart. All units must be inspected and essential measurements made. But how can this be done while the ship is at sea? In order to keep the vessel running smoothly, a precise schedule is drawn up in advance indicating when, in how many hours, oil has to be changed and some part or other replaced. It can be quite "healthy'' and capable of operating for many more hours and still it is removed. Well, and if some part tails to run its allotted time due to some invisible defect, then the ship is in for trouble

We wanted to obtain something akin to a cardiogramme in order to find out how the engine was functioning and if everything was all right

The Diesel Poses Problems

We ran into the first puzzle before we sailed. The engine was not yet running but the instruments were already registering wear! Tiue enough, in a small way — only one micron Still, there it was.

What was the reason? We checked everything carefully in an effort to discover possible errors but found nothing. At dinner in the messroom Nikolai Alexandrov, senior engineer, casually asked the second engineer, who was in charge of the main diesels:

"Are the shafts correctly aligned?" "Yes, we did some 20 turns."

I almost jumped: could it be that these manual turns of the engine had produced that one-micron wear recorded by our instruments?

On that day I myself did 20 turns by hand to test my theory. The instruments showed that the wear had risen by another 0.5 micron I made another 20 revolutions with the same result — no more wear was indicated.

This meant that the procedure of continual wear measurement had to be adjusted by taking into consideration the number of manual turns made before the engine was started.

Step by step, we explored our diesel. 1 am not exaggerating or trying to "spiritualise" our machine, but each engine really has its own unique character, which appreciably affects its behaviour in general and its wear in particular.

Our engine vigorously exhibited its "individuality" when the ship was caught in a storm off the Canaries. And when fishing began, its wear due to extra loads jumped sharply.

Several days passed, and the process persisted. Why? That was another puzzle. But we discovered the reason soon enough: the oil had got dirty. We replaced the oil — almost 250 hours before schedule — and the diesel felt fine again.

Thus arose the technique of uninterrupted measurement of engine wear. It took us a long time to solve this important and difficult task. 1 first tackled the problem of wear back when I was in my fifth year at the institute. I was then working under Professor Vladimir Postnikov. He interested me in this exciting subject.

"Senility" of Technical Equipment?

Wear is an ancient problem. Everything man uses is subject to wear. Within certain limits wear and tear on some article or other presents no great problem to man. But sooner or later comes the critical moment when shoes have to be thrown out and the vessel taken to the repair dock. In the latter case it is vitally important not to miss this critical moment.

Scientists have established the general laws governing the wear on two friction surfaces — we call them "pair". Any newly assembled "pair" registers a higher rate of wear. Later, the process becomes stabilised. This stabilisation lasts until the moment of critical wear.

It must be noted that the engine can also sustain wear when it is not in operation. This is known as corrosive wear (more simply the metal rusts). On the other hand, under certain conditions the engine can run without sustaining wear for a time.

It has been discovered, for instance that starting the engine produces the same degree of wear as five or six hours' operation. That is why a motor car driven in the city with its numerous traffic lights registers 20 to 30 per cent greater wear than a car on the highway.

In a word, the requirements of life gave rise to the science of wear. Like any field, it has many directions. They all involve tests which unfortunately, until now have taken an inordinate length of time and labour, and at the same time have been un reliable. It was inevitable that new testing techniques would be developed and they were: utilising radioactive isotopes and ionising radiations.

Atomic Diagnosing

The diagnosing atom works approxi mately as follows. Each friction surface is activated by being impregnated with radioactive isotopes. As the engine runs, they become detached from the part together with particles of metal. Getting into the lubricants the isotopes increase their radioactivity. Special devices determine how fast radioactivity rises in the oil system — that is the rate of wear! In this process the engine does not have to be taken apart or even stopped. The tests take one-tenth the time and the economic efficiency is 20-25 times greater.

The use of isotopes will make it possible to solve the important pro blem of prolonging the machines’ life This would seem to be a fine thing But in reality everything is much more complicated. First, the personnel must be safely protected from radiation — especially equipped laboratories are required. Secondly, sometimes situations arise which simply cannot be foreseen in the condition of a laboratory.

Professor Postnikov developed a new method of superficial — not deep — metal activation, which does not exceed the radioactivity of the luminous face uf a watch. At last, it became possible to diagnose the en gine in its working condition!

No Theory Without Practice

When I graduated from the Higher Technical School 1 was offered a die sel-repairing job with the whaling fleet. 1 agreed, but on one condition that I would first be allowed to work as a fitter, not an engineer. My request was granted.

The team to which 1 was assigned consisted at first-class masters of their jobs. And I, though a college graduate, had a long way to go before 1 became a real mechanical engineer. The workers liked the fact that 1 was a Master of Sports in boxing in the lightheavyweight category. But being a Master of Sports is one thing and being good at your job is something else again. As for supervising people — you can't learn that in any institute.

For a start, the team-leader gave me the dirtiest job — to clean the exhaust manifold and a diesel crankcase. 1 did the manifold quickly enough. Then I climbed waist-deep into the crankcase, examined it, cleaned it and finally, reached the crankshaft in order to prepare it for repairs as instructed by the team-leader.

I made the essential measurements and found out that the wear was within permissible limits. Did this mean that the shaft did not have to be ground? But it was not so simple as all that: the diesel's crankshaft is not repaired when it is "necessary". It is repaired after the passage of a certain number of running hours there is no saying when, exactly, repairs will become unavoidable. That was how, on the job, 1 became involved with the wear testing problem.

Much later, in Moscow, I ran into Professor Postnikov. Hu inquired about the work I was doing and then suggested that I return to my old subject, which now interested me a great deal.

That was how I went back to the Higher Technical School — this time as an instructor and researcher. After several years’ work I earned a Master's Degree in Engineering.

Recently 1 was on a long business trip to the United States, where I took part in joint Soviet-American investigations. Our US colleagues displayed much interest in our methods. We plan to continue our fruitful cooperation.

Now we are probing into new aspects of the same theme, very interesting ones, I think. Above all, I am preoccupied with methods of longdistance wear control. It is possible that in the near future our idea will find application in cosmonautics, in which it is vital to keep an eye on the working capacity of automatic interplanetary stations, moon-cars and other apparatuses: the rigorous environment of space demands steady, precise information on the "safety margin" available.

Naturally, back on earth, it is just as important to watch over the "health" of mechanisms and machines from afar. Aboard the motorship A. S. Popov there is already an operating unit with a programmed task: it automatically records the engine's wear, and all data come directly to the senior engineer's control panel.

In short, our method is opening up fascinating prospects for active control over wear, or in other words, a possibility to combat the "senility" of engineering equipment with still greater success.

by Leonid POLYAKOVSKY, M.S. (Engineering), senior instructor at the Moscow Bauman Higher Technical School and winner of the Komsomol Prize for his new method of measuring the wear on marine engines at sea.

From the magazine YUNOST

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