Berkshire class locomotives (USA)

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muggins
Posts: 546
Joined: Sat Sep 24, 2016 11:24 am

Berkshire class locomotives (USA)

Postby muggins » Mon Feb 24, 2020 6:20 pm

Stumbled upon this https://www.youtube.com/watch?v=LfevrCvX7l4 shot in 1929, and now wondering what on earth that "hood" thing perched on the front of the smokeboxes is. I see they're well and truly plumbed in, but what on earth were they for?

Bigmet
Posts: 7937
Joined: Tue Aug 14, 2007 2:19 pm

Re: Berkshire class locomotives (USA)

Postby Bigmet » Tue Feb 25, 2020 8:23 am

Boiler feedwater heaters. These were very much in vogue both in Europe and America at the time. Came in various designs in the drive to squeeze a little more thermal efficiency out of the steam loco. I believe this particular design was a 'Coffin'. In general service, feedwater heaters cost about as much as the first cost of the devices and the increased maintenance burden, as the value of the fuel they saved, zero sum...

muggins
Posts: 546
Joined: Sat Sep 24, 2016 11:24 am

Re: Berkshire class locomotives (USA)

Postby muggins » Tue Feb 25, 2020 1:57 pm

Zero sum indeed. And a big difference 'twixt theory and practice ...

Whatever, thank you for solving the mystery.

Bigmet
Posts: 7937
Joined: Tue Aug 14, 2007 2:19 pm

Re: Berkshire class locomotives (USA)

Postby Bigmet » Tue Feb 25, 2020 2:31 pm

muggins wrote:... a big difference 'twixt theory and practice ...

Where quite a lot of it came unstuck was in the difficulty of making the 'device' compact and light enough to go on a locomotive. What worked well on stationary and ship plant had to be so pared down in size and weight for the rail application that either it had insufficient capacity or wasn't sufficiently robust; or in the worst case had both defects.

The Franco-Crosti feedwater heater about the last such significant try on a conventional UK steamer. Didn't have the capacity to improve the necessarily reduced size boiler's performance to match that of a conventional 9F, and then further quickly degraded the loco in service until it was only reliably about 5F capacity. And all this at the cost of a new smaller boiler design, the preheater device itself, and the increased maintenance demand. And it frequently made the crew's life a misery by exhausting into a vortex that directed the exhaust toward and into the cab...


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