EM wheels on 18.83mm track

[John Palmer]

Which is the accident report of Colonel Mount referred to in the extract from the GW Magazine? If that's not known, what is the date of the Magazine? Might be interesting to discover what the accident report had to say on the subject, and the magazine date would help identify the report.

[grovenor-2685]

Note that the increase flange depth in the GW article was within the tolerances allowed by the standards, in effect they were using up some of the allowance for wear.
Keith

[John Palmer]

The report of Lt. Col. Mount referred to in the GW Magazine article must be the one upon the derailment of a GW train on 13th January 1928 on the Severn Valley Line north of Bridgnorth. The derailment's principal cause was rotten sleepering, the fangbolts securing the chairs to the sleepers being unable to maintain the gauge due to such rot.

I get the impression that the railway world was in a tizzy about derailments following the Sevenoaks accident the previous year. That accident took place on 24th August, which Mount gives as the month in which the GWR introduced the deeper flange - in which case it may have been an immediate response to Sevenoaks. Can't help wondering whether the GW Magazine feature was an attempt to put a positive spin upon matters, given that want of maintenance to its own tracks had led to the second tank engine derailment at speed within 4 months.

The increase in flange depth referred to was 3/16ths of an inch, achieved by reducing the permitted limit of wear from 1/2" to 3/16". At a scale of 4mm : 1 foot I make the increase in the depth of flange 0.0625mm - think that's about two and a half thou.

[Noel]

Moredon power station was apparently opened 29.10.1929, confirming that the article is from early that year or from 1928.

I doubt that the Bridgnorth accident would be classified as a high speed one, as the overall line limit was 50mph, according to the 1945 service timetable appendices, with lower limits in some places. This may reflect wartime arrears of maintenance, but there seems no particular reason why the line limit should have been much higher previously.

Noel

[John Palmer]

This was the finding in the report that prompted my characterisation of the derailment as being one at speed:

"[h]aving regard to the distance traversed by the coaches, clear of the track, subsequent to derailment, the light weight of the train, and the damage to the permanent way, I think it quite likely that the speed at the time was nearer 50 and perhaps 55 miles per hour."

Reinforcing my suspicion that there was a pre-occupation at the time with Sevenoaks-style derailments, Lt. Col. Mount concluded that:

"Notwithstanding the evidence, there is little doubt that comparativeIy high speed must have been a contributory factor, and assuming that the tender engines in service on the line had not been running at materially lower speed, the case in my opinion is really another illustration of the more punishing effect which a heavy tank engine is likely to exercise on the permanent way, thus rendering itself more liable to derailment, should weakness exist and the margin of safety be unduly lowered."

[Tim V]

Just spent a day at Pendon.

What has this to do with flanges?

I went to see the Madder Valley in operation. There has been a lot of recent work on it. In one hour watching the layout I saw one derailment.

With care even a 70 year old layout can work well.

[John Fitton]

Just spent a day at Pendon.

What has this to do with flanges?

I went to see the Madder Valley in operation. There has been a lot of recent work on it. In one hour watching the layout I saw one derailment.

With care even a 70 year old layout can work well.

Maybe they use OO gauge wheels on EM track, Tim!

John Fitton.

[Tim V]

The Madder Valley is approximately 16.5mm gauge

[John Fitton]

The Madder Valley is approximately 16.5mm gauge

And probably uses TT gauge wheels

"Reductio ad absurdam" applies here, sorry!!

JF

[Colin Parks]

Just spent a day at Pendon.

What has this to do with flanges?

I went to see the Madder Valley in operation. There has been a lot of recent work on it. In one hour watching the layout I saw one derailment.

With care even a 70 year old layout can work well.

Hi Tim,

So are you saying that one derailment per hour is an acceptable rate for a 70-year old layout, or layouts in general?!

Colin

[Tim V]

Colin

I have seen more than one derailment per hour in most of the exhibitions I have been to, and on layouts considerably younger!

The point I am making is that Madder Valley is actually a museum piece, that occasionally operates, and when it does operate, isn't too bad, considering its age. Regrettably, most shows have layouts where the operators either don't care, can't be bothered, or take easy routes to reducing/eliminating derailments. And that applies to any scale/any gauge.

[Albert Hall]

[quote="Tim V"]Colin



.... or take easy routes to reducing/eliminating derailments.

You mean like putting a speed restriction on over a dodgy bit of track like we do on the full sized railway until the p/way boys can get in there!