Trade secrets

Motor,  Sep 2002  by Cerullo, Bob

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Bob spends a day with an engine that uses pistons as big as a 35-gallon grease drum and learns that his automotive knowledge made the experience not all that unfamiliar.

When I travel around the country, I like to stop into repair shops and kind of nose around to learn how and what they're doing. It doesn't necessarily have to be an auto repair shop-- just anyplace where they fix things and use machines. They could be repairing farm tractors or pizza ovens, for all I care.

A few years ago, I took a guided tour of a plant that makes automobile air conditioning replacement parts. One machine spit out a/c fittings so fast you really couldn't tell what they were until they came to rest in a big collection box.

I recall watching an army of workers at another plant build diesel injection pumps from scratch. Raw steel ingots went in one end of the line and ready-to-install pumps came out the other.

Of course, the all-time best experience is to visit an automobile production line. When I do, I always come away with a better appreciation of what it takes to build the vehicles we work on and often take for granted.

When an old friend, "Swede," asked me to visit with him while he replaced a kind of clutch I had never heard of, I jumped at the chance. I arranged to meet him early on a Sunday morning. When I joined him, Swede was already in what he calls "the basement" hard at work on one of the biggest clutches I had ever seen. The atmosphere was hot, steamy and noisy, and the smell of hot oil permeated the air.

There were others working there, as well. One fellow was at a lathe cutting a thread into a shaft and another was changing a massive diesel oil filter. When I asked Swede why he and everyone else were working on a Sunday, he explained that the job had to be finished in 24 hours, no matter what.

After a while, Swede suggested we take a break, during which time he wanted to show me some interesting stuff. The first thing he showed me was a huge piston-the biggest one I've ever seen. It was the size of a 35-galIon grease drum. Its diameter was about 14 inches and it stood about 30 inches high. The piston we looked at first was recently replaced because it was badly scuffed. Swede told me the new piston cost $10,000. (Get the feeling we're not in an automotive repair shop?)

Then he took me over to a bench where a guy was rebuilding fuel injectors. I've seen plenty of fuel injectors in my time, but that was the first time I've come across one that was as long and as thick as my arm.

Swede next took me to a rack where two more monster-size pistons with their connecting rods were hung on the wall. I felt like a Lilliputian in Gulliver's Travels.

Of course, if you remember your English literature, Gulliver's Travels is a classic work of fiction, but what I was seeing was the real thing. Swede got quite a kick out of showing me the engines with massive pistons whose connecting rods I could hardly hold with both hands, intake and exhaust valves as big as pie plates and bearings the size of wheels.

Each of the two 14-cylinder diesel engines produces 7000 hp. There's no transmission for shifting from forward to reverse; they simply stop the engines and hit a switch that operates a servo that shifts the camshafts so the engines reverse rotation.

Actually, the engines have their own clutches connecting them to a gear arrangement that combines the power and delivers it to a big output shaft as thick around as a 55-gallon oil drum. The clutches are operated by air pressure and are about 15 feet in diameter. They work something like the old external mechanical brakes once used on cars and trucks, only instead of a cable pulling the band tight around a rotating drum, in this clutch, air inflates a cushion that locks the clutch facing to the drum.

The fuel filtering devices use centrifugal force to drive out any impurities that could contaminate the fuel, which is then preheated. Around the basement room there are probably a dozen diesel engines of various sizes. Some run pumps, some run compressors and others do things I haven't yet figured out.

In case you haven't already guessed, Swede had invited me aboard a 750-foot oil tanker. The place he was working is the engine room (the "basement"). Swede and the crew were working this Sunday because the ship had to clear port by Monday morning.

Almost as interesting as the engine room is the wheelhouse. The navigational equipment aboard modern ships boggles the mind. There are two GPS systems, not much different from those in some luxury cars, to pinpoint exactly where the ship is located in terms of longitude and latitude. The Captain told me he loves all the amazing electronics, but still keeps an eye on the old compass. Old habits die hard, I guess.

In addition to aids to navigating the ship, there are all kinds of devices used for loading and unloading jet fuel or diesel fuel from their tanks. If it's done wrong, it can spell big trouble. When they load jet fuel or gasoline, they have to pump inert gas into the tank to prevent an explosion.