Friday, 15 April 2016

Re-Chained Malady

Last time I wrote about fitting the two drive chains, I'd been concerned that one chain seemed much slacker than the other. I counted the number of links on each chain and checked that the corresponding sprockets had the same numbers of teeth. All were present and correct. 

Fellow member of the Sentinel Drivers Club Keith Reynolds visited the Midsomer Norton station open day at the end of February 2016. He explained that chains can stretch and that this was probably the cause. The stretch can be detected by laying the chain on its side and lifting one end. The curvature of the chain indicates the level of wear in the link roller bearings. The greater the curve, the greater the wear.

Although I could not do this while the slack chain was in situ, kicking it showed that it had a lot of sideways play.

So I decided that the best option was to simply replace it with another of the spare chains and take a chance on the result.

I was lucky as can be seen below. The two chains are very similar in tension now and I didn't have to do any axle adjustment.
Nearside chain replaced (the less shiny one)
The two chains are now similarly tensioned.
So a day well spent.

My apologies for the lack of blog material lately. Actually operating 7109 is great fun but without a 30ft selfie stick, it's very difficult for the driver to get any of his own photos!

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