Ivatt Black Five boilers

[1165Valour]

Starting in early 1947, George Ivatt made some modifications to the design of the Class 5's then being built. One of these involved moving the top feed to the front ring of the boiler, beginning with No. 4998. Does anyone know why this was done, and how the performance of the Ivatt machines compared with the Stanier ones?

Edited March 10, 2020 by GWRSwindon

[1165Valour]

Does anyone know of any Class Fives having their original Stanier boilers replaced by Ivatt ones, through overhauls and the like?

[Steamport Southport]

I think 45337 has an Ivatt boiler. In that it has the 28 element superheater.

 

 

 

Jason

[PenrithBeacon]

There are books published by Wild Swan and the RCTS which will provide the answer to the OP.

[LMS2968]

The idea was to move the incoming boiler feed water, which was relatively cold, away from the dome where you wanted to entrain steam at its highest temperature into the main steam pipe.

 

I doubt that any of the English works would have swopped boilers around, type for type, but St Rollox did on a regular basis; anything could and did come out married to anything!

[jim.snowdon]

If St Rollox could do it, so could Derby, Crewe and Horwich. All of the LMS works adopted a policy of next available standard component, so as long as boiler would fit the frames, it could be done. Adjustments to the plumbing are relatively small matters. After all, look at the way some of the smaller GWR locomotives routinely changed from boilers with top feed to boilers without and back again.

 

Jim

[LMS2968]

Horwich and Crewe, I'm less sure about Derby, always stencilled the engine number on even quite minor components to ensure that they were replaced on the original loco. Boilers would interchange between engines, but there would be a stock of available ones and efforts would be made to fit a similar type. Although the plumbing can be moved around, even putting it back on the same loco can sometimes present challenges, as I'm currently finding out, so there would be an attempt to keep things the same whenever possible. But St Rollox did earn a reputation for ignoring what was original fittings and shoving on anything; the English works did not.

 

As a case, the handrail knobs on the LMS Pacifics were different between streamlined and non-streamlined examples, and both types kept their original types to withdrawal. There were two exceptions: 6225 finished up with non-streamlined type and 6255 with the streamlined. Notice the similarity in the numbers?

[markw]

There wern't many Ivatt boilers with the short smokebox that would fit a stanier short wheelbase engine, most Ivatt boilers had the longer smokebox.

[LMS2968]

Generally, and against common belief, the smokebox stayed with the engine and not the boiler. The sloping throatplate boilers were all the same length, so could in reality be fitted to any Black Five with the correct frame stretchers, the length od smokebox was irrelevant..