SELF SEAL DANGER
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• I was recently supplied with a demonstration tractor unit from a well known British manufacturer, which was fitted with tapless selfsealing air Suzies. These I connected to my three-line straight-air trailer.
My regular driver loaded 20 tonnes at Felixstowe, delivered to Corby and returned to base safely. On the second day I did a similar load to Norwich. En route to Norwich, driving through some of the thickest fog I have seen for years, I learned, to my near fatal cost, the subtle hidden dangers that are created by connecting tapless, self-sealing air lines, to non-sealing couplings. As the female sealers open, when connected, thus giving normal service to the red and blue lines i.e. hand brake and dead man, the vital service line, being a male connector from the tractor, is not opened by the female on the trailer, thus rendering the braking system totally inoperative on the trailer, as far as the foot brake is concerned.
I am now aware that the problem dates back some ten years or more and received considerable publicity at the time. I can only say, however, but it foxed several old and experienced drivers before my garage could tell me what was wrong.
It seems a hideous oversight that this entirely unnecessary problem has not long since been eradicated. I wonder how many others have been conned by this system and how many accidents, fatal or otherwise, have happened as a result.
Barry J Dorling Barry I Dorling Transport Hunston, Suffolk Editor's reply: This sounds as :1 11 could be a recurrence of a problem uncovered six years ago by the Freight Transport Association: the illustration below is taken from the FTA journal "Freight" of March, 1981. It was found that some Berg self-sealing valves were fitted with a flexible sealing washer which could distort and block air flow through the valve. Berg quickly introduced a modification and valve replacement programme.
Barry Dorling's lucky escape clearly illustrates the importance of the practice taught by HGV driving schools which even experienced drivers too frequently do not carefully follow: that is of checking the operation of semi-trailer brakes, as well as all its lights, after coupling a tractive unit.