WARNING: Reading this page will change your life. You'll never pass a pylon without trying to spot the objects discussed below...
Next time you are close to a pylon, look carefully at where the wires are attached to the arms of the main tower. If you do, you will see that there are dumbbell shaped objects clipped onto the wires. You can just see them on the wires in the pylon picture and there is a zoomed in view as well that gives a better view These are Stockbridge Dampers and are named after George H Stockbridge, who was granted a US patent for his invention in 1928. In the patent he says:
My invention relates to means for preventing objectionable vibrations in suspended cables, such as are used in electrical transmission lines and the like...
When the wind blows across the pylon lines, it can cause them to vibrate. The effect is exploited in a musical instrument called an Aeolian harp (named after Aeolus, the ancient Greek god of the wind) where the wind blowing across metal strings causes them to vibrate and produces a rather beautiful haunting sound. In the case of pylon lines, however, because the wind blows relatively often, the wires will be vibrating for significant periods of time leading to damage from stress fatigue. This could cause the cables to break and you can demonstrate the effect easily by bending a straightened paper clip a few times until it snaps. What George Stockbridge discovered was that if something suitable is attached to the cables, you can reduce the vibrations almost to zero. In this way, the damage to cables that would be caused by stress fatigue is eliminated and so the lifetime of the cables is greatly extended. The problem is most likely to cause damage to the cables near to where they are attached to another object and this is why the Stockbridge dampers are located close to where the cables pass a pylon.
Spotting Stockbridge dampers is a fun game for all the family and can help to pass the time on long journeys. You get double points if you spot them in pairs on the same wire and triple points if you spot them on the cables of a suspension bridge.
Where it all began
This was the first pylon ever to feature on my Pylon of the Month blog back in June 2008. To accompany the picture, there was a very brief write up.
This Pylon is between the village of Kennington and the River Thames near Oxford.
I’d cycled out from home on a Sunday morning with my son to take the picture. He would have been 10 years old and claims to remember this first pylon expedition, which was the result of my day job as a Physics teacher. Whilst teaching electricity, I’d visited a Pylon of the Month website to give a bit of light relief to classes learning about electricity and together we’d had a laugh about the kind of weirdo who ran a pylon website. Then it stopped working and I faced a decision; accept that it had gone for ever or do something about it. Knowing pretty much nothing about blogs or how to set them up, this was my chance to learn and the picture above was the result. I then did nothing for quite a few months until Pylon of the Month got its first comment on 24th March 2009.
Can we have a new one please?
That spurred me into action and in April 2009, the pylon photo below was taken whilst on holiday near Ludgvan in Cornwall. The first hint that the new Pylon of the Month was taking off was the comment that followed days later.
This is rather amusing because I believe that I might have seen this exact pylon out of the window when I was driving my car!
Great website had much fun at work with the lads...!
‘The lads…’ - Pylon of the Month was now really up and running.