Panniers or saddle?

[spikey]

Mrs Spikey has once again posed a question I can't answer, so I turn to the collective wisdom here ...

 

If in the early 20th Century I had been designing an 0-6-0 tank locomotive, what considerations would have determined whether I went with pannier tanks or a saddle tank?

 

 

[eastglosmog]

What I have read is that the received wisdom is that Belpair firebox = Pannier tank, Round topped firebox = saddle tank, for ease of fitting.  But I am sure there are plenty of exceptions!

[spikey]

Ah yes ... firebox shape hadn't dawned on me (and I now fear the supplementary question from the good lady "So what determined firebox type?").

 

Your mention of "ease of fitting" has got me wondering - what exactly do pannier tanks typically attach to? Do they sit over the boiler cladding, or does that stop above and start again below?   And come to that, what actually takes the weight of a saddle tank and its contents? 

 

Oh gawd, what have I started now ...

[Wickham Green]

A Belpaire 'box has a greater heating surface within the same width, length & depth ............. but it probably ain't quite that simple !

[Steamport Southport]

Efficiency.  A Belpaire firebox was vastly more efficient than a roundtop.

 

There was also problems with water sloshing around saddletanks at speed. The main reason that saddletanks fell out of favour for anything other than shunters.

 

As for attachments they attach to the sides of the boiler. They literally are "panniers" like you fit to a bicycle.

 

Scroll down to the bottom here and click the bottom picture. It's the tanks from 7754.

 

http://www.llangollen-railway.org.uk/sloco7754.html

 

 

Jason

Edited March 10, 2020 by Steamport Southport

[Miss Prism]

some bits for 7754

[Gordon A]

Don't forget the supports at the front and rear of the tanks that transmit the weight to the running plate.

 

I am not so sure about the sloshing of water being a reason as there are a high percentage of industrials fitted with saddle tanks.

 

Both pannier and saddle tanks gave improved access to the inside motion over side tanks for daily oiling.

 

Gordon A

[JimC]

On GWR pannier tanks the weight is mainly taken by supports front and rear underneath the tanks. On a 94 both go to the footplate. On a 57 the rear one goes to the footplate, and the front one to the saddle/smokebox assembly. On a 1500 the front one goes to a transverse I beam under the boiler, and thus to the frames, while the rear one is riveted directly to the frames. There are straps across the top, but they don't seem to be large enough to take really serious weight.

[spikey]

4 minutes ago, JimC said:

On GWR pannier tanks the weight is mainly taken by supports front and rear underneath the tanks ...

 

Ahah!  Thanks, JImC.  So I guess the boiler is clad pretty much as usual, the panniers butt up against that with the weight taken on those supports, and the straps over the top just hold the whole shebang together.

 

Right ho - all we need to know now is what exactly takes the weight of a saddle tank full of water, and is there cladding all the way round the boiler under it?

[doilum]

Only slightly off thread: can anyone think of an industrial with a Belpaire firebox? ( Excluding ex main line locos?)

Edited March 10, 2020 by doilum
Predictive text error

[Harlequin]

Also off-topic: "Running plate" vs. "Footplate". Discuss.

 

Would it be correct to say that outside the cab it's called the "running plate" while the "footplate" is inside the cab?

 

[Nearholmer]

1 hour ago, doilum said:

can anyone think of an industrial with a Belpaire firebox? (

Kerr Stuart ‘Victory’ class?

[Compound2632]

1 hour ago, Harlequin said:

Also off-topic: "Running plate" vs. "Footplate". Discuss.

 

Would it be correct to say that outside the cab it's called the "running plate" while the "footplate" is inside the cab?

 

 

Also "platform".

[Martin Shaw]

3 hours ago, Steamport Southport said:

Efficiency.  A Belpaire firebox was vastly more efficient than a roundtop.

 

There was also problems with water sloshing around saddletanks at speed. The main reason that saddletanks fell out of favour for anything other than shunters.

 

I don't think I would go as far as vastly more efficient, marginally better at releasing steam from boiling water but this is as much due to the distance betweeen the inner and outer firebox as it is the upper shape, and then there are such things as free gas area, tube dimensions, overall heating surface, it really is quite scientific, Consider for a moment both the LNER and the SR who largely used roundtop boilers without any apparent inability to pull trains, an A4 boiler, once the drafting was sorted in the late 50s, was as good a steam generator as anything else. Additionally a Belpaire boiler is greater in both capital cost and subsequent maintenance, so yes it is better but the contrast is marginal.

 

Water sloshing about was one of the contributory factors in the Sevenoaks accident of 1927, a River class with side tanks. It's more to do with centre of gravity than any particular shape, the disadvantage of a saddle tank is that the contents are heated by the boiler rather more than in other shapes so potentially leading to an earlier injector failure, and I suspect the cost of manufacture might be a bit greater.

 

Regards

Marrtin

[Martin Shaw]

2 hours ago, spikey said:

 

Ahah!  Thanks, JImC.  So I guess the boiler is clad pretty much as usual, the panniers butt up against that with the weight taken on those supports, and the straps over the top just hold the whole shebang together.

 

Right ho - all we need to know now is what exactly takes the weight of a saddle tank full of water, and is there cladding all the way round the boiler under it?

Spikey

An Austerity tank holds 1200 gallons so weighs 12000 lbs, 5.3 Tons or 5454Kg, the empty tank maybe 2 tons which all sit on the boiler, in essence,  and yes the boiler cladding goes right around.

Martin

Edited March 10, 2020 by Martin Shaw

[Siberian Snooper]

You don't want the feed water to get warm, otherwise the injectors won't work.

 

 

[Steamport Southport]

3 hours ago, Gordon A said:

Don't forget the supports at the front and rear of the tanks that transmit the weight to the running plate.

 

I am not so sure about the sloshing of water being a reason as there are a high percentage of industrials fitted with saddle tanks.

 

Both pannier and saddle tanks gave improved access to the inside motion over side tanks for daily oiling.

 

Gordon A

 

Did any industrials work at speed though? I don't mean toddling about at twenty to thirty miles per hour. More getting up to speeds of over 60MPH. GWR 54XXs and others were timed at working trains at speeds of about 75MPH.

 

 

 

Jason

 

[Compound2632]

Are there many instances of non-Great Western engines with pannier tanks? My understanding is that they were more-or-less forced on the Swindon drawing office once they'd committed to re-boilering old 0-6-0 saddle tank engines with Belpaire boilers - so more a case of necessity than any fundamental advantage. Of course advantages may have become apparent after the event - forward visibility perhaps? It's notable that panniers were only used for these rebuilt saddle tanks and subsequent locomotives whose design was derived from them; all other Great Western tank engines had conventional side tanks.

[The Johnster]

5 hours ago, doilum said:

Only slightly off thread: can anyone think of an industrial with a Belpaire firebox? ( Excluding ex main line locos?)

Yes, and it’s available RTR; Dowlais 0-4-0. 

[The Johnster]

1 hour ago, Compound2632 said:

Are there many instances of non-Great Western engines with pannier tanks? My understanding is that they were more-or-less forced on the Swindon drawing office once they'd committed to re-boilering old 0-6-0 saddle tank engines with Belpaire boilers - so more a case of necessity than any fundamental advantage. Of course advantages may have become apparent after the event - forward visibility perhaps? It's notable that panniers were only used for these rebuilt saddle tanks and subsequent locomotives whose design was derived from them; all other Great Western tank engines had conventional side tanks.

Rhymney Railway (period spelling) K class outside framed 0-6-2ST rebuilt by GW as pannier, also RSH ‘long boiler’ pannier tanks for NCB in Co. Durham.  GW panniers were not of course all derived from saddle tank designs; 94xx and 15xx were completely new, with the 94xx rooted in the 2251 and the 15xx rooted in the USATC S100 if anything. 

[eastglosmog]

2 hours ago, Compound2632 said:

Are there many instances of non-Great Western engines with pannier tanks? My understanding is that they were more-or-less forced on the Swindon drawing office once they'd committed to re-boilering old 0-6-0 saddle tank engines with Belpaire boilers - so more a case of necessity than any fundamental advantage. Of course advantages may have become apparent after the event - forward visibility perhaps? It's notable that panniers were only used for these rebuilt saddle tanks and subsequent locomotives whose design was derived from them; all other Great Western tank engines had conventional side tanks.

The Baldwin and Alco pannier tank locos for the WD in WW1 (narrow gauge,of course).

[JimC]

3 hours ago, Compound2632 said:

to re-boilering old 0-6-0 saddle tank engines with Belpaire boilers - so more a case of necessity than any fundamental advantage.

Interestingly quite a few of the earliest 0-6-0 tanks of that lineage were side tanks. 
The first of the 1076 class of 1870 had side tanks, then short saddle tanks, then full length saddle tanks, then panniers. The 633 class of 1871 were side tanks for their entire lives, but their immediate successors were saddle tanks which became pannier tanks. The 1813s of 1882, arguable the direct ancestors of the 57s also started live as side tanks and went through saddle tanks to pannier tanks. Conversely the 517 class, ancestors of the 14xx, started life as saddle tanks in 1868, but were soon converted to side tanks which they never changed from. There doesn't seem to be an especial pattern. I expect it was down to detailed design factors.

[brianthesnail96]

The lovely Kitson "Long Boiler" 0-6-0PT for the Consett Iron Company (2509 is preserved) and a handful of oddball Bagnalls with Walschaerts valve gear (originally intended to be metre gauge for export but altered to standard gauge and used in this country instead at the insistence of the Ministry of Supply, 2613 survives) are a couple of standard gauge industrial examples. No idea if any of the metre gauge ones survive elsewhere.

Edited March 10, 2020 by brianthesnail96

[Nick Holliday]

12 hours ago, Compound2632 said:

Are there many instances of non-Great Western engines with pannier tanks? My understanding is that they were more-or-less forced on the Swindon drawing office once they'd committed to re-boilering old 0-6-0 saddle tank engines with Belpaire boilers - so more a case of necessity than any fundamental advantage. Of course advantages may have become apparent after the event - forward visibility perhaps? It's notable that panniers were only used for these rebuilt saddle tanks and subsequent locomotives whose design was derived from them; all other Great Western tank engines had conventional side tanks.

The LBSCR in Craven days had a number of pannier tanks, such as this shunter that ended up on a Welsh railway.

 

Photo courtesy of Dave Searle and the Brighton Circle website.

 

 

 

 

[doilum]

16 hours ago, Nearholmer said:

Kerr Stuart ‘Victory’ class?

Thanks. Haven't built one of those yet!