"Getting Hold of Her Water"

[CoggesRailway]

Currently there is a "Steaming Around Britain" Magazine/Book out by a retired Southern fireman. It has lots of footplate stories and write ups of locomotives. I recomend it - I bought mine in Sainsburys, but think it's in Smiths too.

Anyway my question is this: in the context of climbing the Devon banks he talks of stopping her slipping before "she gets hold of her water and clamity ensues" so what does that mean???

Wasn't sure if this is live steam or full scale- but guessed people who may know this hang about in here.....

 

[dunnyrail]

This is probably referring to the loco 'Priming' in effect lifting water to the cylinders rather than steam. This can have disastrous effects on the full size thing as Water does not compress as steam does. hence cylinders can have the front blown off or even worse coupling rods can break, dig into the ballast and cause a derailment. Nasty.
JonD

 

[CoggesRailway]

Ok- but why would slipping do this? Because of the sudden acceleration of the stroke rate I guess?

 

[dunnyrail]

Heavy slipping on a bank cn cause vibration and subsequent surges in the water within the boiler. That could then cause the water to be lifted through the steam pickup pipe in the dome.
JonD

 

[KeithT]

I once witnessed a rebuilt Scot do exactly that hammering through Hellifield station in the 1950s.
It blew the front of the cylinder clean off and it ricochetted along the platform. Fortunately, I was on the other side the station building. I have never seen so much steam!
There was a post on GSM with photographs of a Southern (?) loco which suffered something similar only last year.

 

[KeithT]

deleted!

 

[Neil Robinson]

The Peppercorn A2 "Blue Peter" infamously slipped and primed when leaving Durham on the 1st October 1994. One theory was that the priming prevented the driver closing the regulator, what is certain is that the uncontrolled slipping lasted for long enough for the locomotive to suffer major mechanical failure. Apparently both outside sets of valve gear were destroyed, the leading coupling rods were bent, all coupled wheel axle boxes were damaged and the left leading driving wheel moved on its axle.

 

[minimans]

The Peppercorn A2 "Blue Peter" infamously slipped and primed when leaving Durham on the 1st October 1994. One theory was that the priming prevented the driver closing the regulator, what is certain is that the uncontrolled slipping lasted for long enough for the locomotive to suffer major mechanical failure. Apparently both outside sets of valve gear were destroyed, the leading coupling rods were bent, all coupled wheel axle boxes were damaged and the left leading driving wheel moved on its axle.

Luckily they had one they had finished earlier.....................................................Get down Shep...................

 

[New Haven Neil]

I would say that the huge increase in steam delivered by the boiler in a slip causes foaming of the water within the boiler. This occurs as the localised pressure reduction resultant from the high steam flow causes more bubbles of steam to form from the heating surfaces of the boiler, and travel violently to the surface of the water. The increase of bubbles increases the volume of water within the boiler - think like pouring a beer too fast.

 

[pugwash]

think like pouring a beer too fast.

No such thing, at least not when it's being poured down my neck
Does priming only happen due to wheelslip or does it occur on other occasions? I must admit I had never heard of this until now.
And just how do you tell someone you just blew up their expensive engine? Ouch. :crying:

 

[New Haven Neil]

It can happen as a result of several things, having too high a water level in the boiler, the boiler being 'dirty' inside (that's why full size ones got washed out every 14 days or so, in the steam days - water treatment and blowdown of the resultant 'mud' nowadays makes it less frequent), slipping, opening the regulator wide suddenly......it's part of proper management of a boiler/engine.

I should think a driver and fireman would be 'on the carpet' to explain why such a thing did happen, if a cylinder cover blew off!! It may not have been their fault of course, if the loco was overdue a washout........

The recent occurence was to a Standard 5, I think, on the Mid-Hants? Not sure how it happened, but the whole cylinder casting broke, not just the studs holding the front cover on. Expensive.

Older slide valve (as opposed to piston valve) engines could get away with priming more, as the slide ('D') valve could be forced off it's face by the water pressure, whereas a piston valve can't be. Hence piston valve engines have relief valves (like a little safety valve) on both cylinder end covers, but these are small, and may not clear sufficient water to save damage.

Here endeth the lesson, sorry if I'm lecturing!

edit for sp.

 

[brianthesnail96]

Interesting question- I knew the answer as "priming" but I didn't know the answer to "why"- ta Neil & Neil!

Blue Peter's incident certainly demonstrates the power of a steam locomotive though- the forces involved to do that much damage must have been pretty big.

 

[whatlep]

http://www.steamsoundsarchive.com/13/audio/19940814.mp3

That link is a sound recording of the BLUE PETER incident at Durham,

the slipping/ wheelspin starts hald way through, suggest you turn the volume down a bit.

Blimey! There's slipping and then there's this. Out of control is too mild a term. :timeout:

 

[pugwash]

Here endeth the lesson, sorry if I'm lecturing!

Not in the least, very interesting but thankfully not an everyday occurence.
I will no longer moan constantly for days when I drop a Stainz :impatient:

 

[Ferrysteam]

When Mallard did her world speed record of 126.4 mph she bent her coupling & connecting rods,probably through the sheer speed as probably did Blue Peter.

 

[CoggesRailway]

Thanks Chaps! I tried to get the answer on the web - but this forum came good! In the context of the book the regulator gettin stuck open makes particular sense.

 

[George]

the BR 4MT at the Mid Hants Railway (Watercress Line) blew the front of one of its cylinders off last year while hauling the first train of the day during a steam gala
fortuantly it didnt happen in a station and being early morning there wasnt many linesiders taking photos but the crew and peeps lining out the first few carriages got a massive shock when it went bang and got a facefull of cylinder foam stuff and steam...

 

[Neil Robinson]

When Mallard did her world speed record of 126.4 mph she bent her coupling & connecting rods,probably through the sheer speed as probably did Blue Peter.

Gresley's conjugated motion which provided the valve events for all three cylinders from the two outside sets of valve gear wasn't perfect.
The middle cylinder tended to do more than its share of the work and this tendency grew worse with increasing speed and temperature, so Mallard's center big end overheated and suffered consequent damage on the record run.
The A4s were fitted with more substatial big ends with "stink bomb" overtemperature detectors and the valve setting altered to reduce the maximum cut off of the center cylinder's valves.

 

[New Haven Neil]

Yes Neil, quite correct, but I hesitate to mention the improved big end was of (shudder ) GWR design.....#choke#

 

[LTfan]

I remember reading a story that signalmen on the LNER main line could tell how long a loco had been used since last overhaul by how badly the three exhaust beats were out-of-true (syncopated?)

David