Stop The Shaft!

When something is wrong with a piece of machinery, the prudent thing to do is to stop, find the problem, and fix it. If you’re on a naval warship, for instance, and you hear a rumbling sound in the Main Reduction Gears, the first thing you do (assuming there’s not a torpedo chasing you) is stop and lock the shaft.

To stop and lock the shaft on a Trident submarine, the Engineering Watch Supervisor goes to Shaft Alley, picks up a phone that’s located there for this very purpose, and directs the Throttleman (who lives in Maneuvering, a small room that’s about as far from Shaft Alley as you can get and still be in the Engineroom) to open & close the Forward & Back throttles until the shaft is stationary long enough to say “the shaft is stopped” three times…then, a mechanical operator pushes in the mechanism to lock the propulsion train.

Nobody stopped the shaft like my friend Curt. Most people did “play by play” – Curt did “color.” He knew every synonym for words like “creeping” and “crawling” that have ever been published in a thesaurus. “The shaft is edging forward…the shaft is slinking back…the shaft is inching forward EVER SO SLIGHTLY…barely…the shaft is stopped, the shaft is stopped, the shaft is stopped.”

Luckily, we never had to stop the shaft for any purpose other than training, but not every boat has been so fortunate, and the consequences can be serious:

In 1987, the Trident submarine USS Nevada suffered a reduction gear failure soon after a maintenance refit that was performed by a shipyard who was bidding on a contract to build Trident submarines. The cause was a faulty part that was replaced under warranty by the manufacturer. Regardless, the shipyard still didn’t get the contract.

Last year, sailors onboard USS Georgia, another Trident, heard a “Whump! Whump! Whump!” (that’s official technical jargon; I got it straight from the Navy Times) coming from their reduction gears. It appears that, instead of stopping and locking the shaft, they continued to operate for several days, at varying speeds, trying to diagnose the problem. The subsequent repairs cost over two million dollars, took the boat into the yards for three months, and caused them to miss a critical deployment in support of the NATO mission against Libya, which required their Tomahawk missile-launching capability. As a result, an officer and a senior enlisted man both lost their jobs, three sailors went to Captain’s Mast, and three more got letters in their Permanent Record.

Not all problems have such dire consequences, but it begs the question: what are you living with, because you think you can? I know of a company that found out that they were “living with” compressed air leaks, totaling 6.5 SCFM a while back. They used an Ultrasonic Leak Detector to find a total of 17 mostly very minor leaks. Now, 6.5 SCFM doesn’t sound like much, but if you do the math, it’s over a million cubic feet per year. I know this story is true, because the company was EXAIR.

Before you go on “living with” a problem that’s costing you lost compressed air, I encourage you to give us a call. Between our Ultrasonic Leak Detectors, Digital Flow Meters, and Efficiency Lab, we can help.

Russ Bowman
Application Engineer
EXAIR Corporation
(513)671-3322 local
(800)923-9247 toll free
(513)671-3363 fax

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