"Getting Hold of Her Water"

[Rhos Helyg Loco Works]

While there have been instances of the regulator being stuck open, that is not usually the cause of violent slipping as demonstrated by Blue Peter.

The usual cause of a "stuck open" regulator is water passing through the regulator valve at high pressure and so preventing the valve from shutting. However, the slipping (and damage) only really starts once that water has actually passed through the regulator. The water arrives in the superheaters where it turns instantly to high-pressure steam and then passes uncontrolled to the cylinders, so causing the wheel slip. For this reason closing the regulator after the water has been picked up has little or no effect.

 

[New Haven Neil]

Listening to my collection of Peter Hansford records, it seems V2's were probably the worst of the 3 Cylinder Gresley designs for being out of beat! Some were truely awful!

r.e. Blue Peter, I read at the time that one of the issues in the accident was that the driver was unfamiliar with the operation of the multiple valve regulator some of the A2'as had (including 60532), and when she initially slipped and he couldn't close it, he thought it was 'gagged' as can happen to a conventional valve, and opened it wide to then slam it shut - except he then couldn't because of the huge steam flow and little back pressure! The correct procedure would have been to have wound her into mid gear and then close the regulator as backpressure built up. Training issue. It was a fearsome accident for sure, the video is quite horrendous.

 

[Neil Robinson]

r.e. Blue Peter, ......... The correct procedure would have been to have wound her into mid gear and then close the regulator as backpressure built up. Training issue. It was a fearsome accident for sure, the video is quite horrendous.

No argument there. However at least one account ( http://en.wikipedia.org/wiki/LNER_Peppercorn_Class_A2_60532_Blue_Peter )states that the driver attempted to do just that but as soon as he released the catch on the reverser it span round to full gear, injuring the driver's arm in the process. I've never driven a loco with a screw reverser, but I know you need a very good grip on the reversing lever before releasing the catch with a lever reverse engine.

BTW I was unaware of the GWR's influence in the improved A4 big end. I'd always heard them called "marine big ends". Mind you I think all the blokes concerened were ex LNER/Eastern region types!

 

[New Haven Neil]

I wasn't aware of that, Neil, an interesting point, and a plausible explanation. I bet the driver took a nasty knock from that. Although I have very briefly driven a loco with screw reverse, I doubt we exceeded 20 mph....so there certainly wasn't anything like the forces coming through the reversing linkage! I have certainly learned to ease the throttle on a lever reverse loco before releasing the catch.....you only do it once......

On the face of it, I wouldn't have thought the screw thread on a screw reverser was 'reversible', but there must have been enormous forces at play in that slip.

 

[New Haven Neil]

Oh, re the big end, I can't remember the guys name, but he went to the ER from Swindon in BR days.....I think the tale is in Loco Panorama or one of those books. It's been a while since I read it. Or is it in the RCTS 'Greenie'....???? Anyway, somewhere...!!!!

 

[Ferrysteam]

It seems to me that someone has let too much water into the boiler allowing it to overflow into the steam collector and directly into the elements(super heaters)causing instant superheated steam,forcing the the regulator to stay open.Thank God it didn't blow an element or fire tube,it would have been a lot worse.

 

[Neil Robinson]

It seems to me that someone has let too much water into the boiler allowing it to overflow into the steam collector and directly into the elements(super heaters)causing instant superheated steam,forcing the the regulator to stay open.Thank God it didn't blow an element or fire tube,it would have been a lot worse.

There is little doubt that the water level was near the maximum and that the train was restarting from an unscheduled stop at Durham. I strongly suspect that the fireman had a good fire and wasn't expecting the stop so he or another crew member decided on the acceptable procedure of topping up the boiler water during the stop in order to prevent the safety valves lifting in the station. I doubt that the water level was high enough to cause priming without the added effects of the slip as the train restarted successfully from the station prior to the disastrous slip.
A blown element or tube wouldn't have been good but IMHO there was a greater real danger of throwing a rod with the potential of causing far more damage than a blown tube or element.

 

[Ferrysteam]

If a tube or element blew and the fire was being stoked the crew would almost certainly have been badly scalded or even killed,what could have been worse?

 

[New Haven Neil]

If she threw a rod, it could have penetrated the boiler shell....that would have killed more than the crew. The danger of such accidents cannot be underestimated.