So I’ve seen these smoke deflectors on steam locos from time to time. But I had never seen them in use. I’m not sure that I understand the principal of blowing the exhaust back over the locomotive. At the beginning of this film, the Big Boy on the high rail layout, is what I am speaking of.
Well at speed, high speed, the air flowing over that “deflector” will help create a draft from the smoke-box. By helping to draw the exhaust gasses out of the smoke-box, that in turn helps to draw more exhaust gas through the flues from the firebox.
Check
http://locomotive.wikia.com/wiki/Smoke_Deflectors
and
https://answers.yahoo.com/question/index?qid=20100526235824AAoRwxi
I can understand the principal behind “Elephant Ear” type deflectors, but with the type of detector seen on the Big Boy in the video, the smoke would be drawn back over the cab, obstructing the engineer’s view. At least it seems that’s what would happen, in my mind.
This photo shows a loco fitted with “Blinkers” as they are known here (after horse blinkers).
You will notice that the blinker extends down to the foot plate giving a box like structure as an air intake .
Forward movement of the loco causes air to pass into the box , the frontal area of which is larger than the area behind that bleeds out the air ; this starts to compress the air locally , and also the air is acted on by the Venturi effect of the curve of the boiler . Thus an accelerated mass of air is thrust upward and backward , this fairly solid wedge of air pushes the exhaust smoke into a more concentrated mass going along the top of the boiler where the round boiler produces further upward air flow and makes the smoke go where it’s required .
Finally , the top of the blinkers are not curved in , it is arguable that it is necessary to do so .
The photo was taken from an internet side called Ian’s Pictures .
Mike
They were called “smoke hoods” or “stack covers”. They were used to protect the tunnel linings from the stack blast. Paul
As Paul notes - the incredibly damaging blast and raised risk of asphyxiation for the crews of the very large locos on the SP led to the development of the cab-forward locomotive.
More, it was these problems that led the GN to the use of electrics in the Cascade tunnels. Bigger consists meant bigger locos were needed, and although the GN had a great fleet of articulated locos of extreme beauty and power, it was the Z1 and Y1 electric that ruled the long holes through the state.
tac
Ottawa Valley GRS
Dan Padova said:
I can understand the principal behind “Elephant Ear” type deflectors, but with the type of detector seen on the Big Boy in the video, the smoke would be drawn back over the cab, obstructing the engineer’s view. At least it seems that’s what would happen, in my mind.
Dan,
The type of deflector on the Big Boys works differently from the standard “elephant ears”. For starters the Big Boys have two stacks, in order to direct all that smoke away from the engine the deflectors were selectable i.e. one or the other would swivel up from either the right or the left (or both) to divert the smoke (and the blast force).
One of the reasons mentioned for the arrangement was the blast force of the stacks in tunnels which was (apparently) strong enough to detach material from the roof of tunnels (tunnel lining). http://cs.trains.com/ctr/f/3/t/80397.aspx
Interestingly the deflectors were seldom in use on the following series of pictures http://www.railarchive.net/bigboys/index.html# except on stationary display engines like this one with both deflectors in the up position http://www.railarchive.net/bigboys/up4012.htm
On an experimental basis elephant ears were fitted on Big Boy 4019 http://cs.trains.com/trn/f/740/t/169692.aspx
Not exactly a smoke deflector, but here is some interesting reading on Santa Fe smoke stack extensions:
http://www.trainorders.com/discussion/read.php?10,696411
Here is Santa Fe 2926’s stack being tested:
Hans-Joerg Mueller said:
Dan Padova said:
I can understand the principal behind “Elephant Ear” type deflectors, but with the type of detector seen on the Big Boy in the video, the smoke would be drawn back over the cab, obstructing the engineer’s view. At least it seems that’s what would happen, in my mind.
Dan,
The type of deflector on the Big Boys works differently from the standard “elephant ears”. For starters the Big Boys have two stacks, in order to direct all that smoke away from the engine the deflectors were selectable i.e. one or the other would swivel up from either the right or the left (or both) to divert the smoke (and the blast force).
One of the reasons mentioned for the arrangement was the blast force of the stacks in tunnels which was (apparently) strong enough to detach material from the roof of tunnels (tunnel lining). http://cs.trains.com/ctr/f/3/t/80397.aspx
Interestingly the deflectors were seldom in use on the following series of pictures http://www.railarchive.net/bigboys/index.html# except on stationary display engines like this one with both deflectors in the up position http://www.railarchive.net/bigboys/up4012.htm
On an experimental basis elephant ears were fitted on Big Boy 4019 http://cs.trains.com/trn/f/740/t/169692.aspx
Thanks Hans. Some interesting information in those links. Sadly, the Union Pacific Big Boy, pictured at Bellows Falls, Vermont may be the same one that I saw two years ago at Steamtown in Scranton, Pa. Whether it’s awaiting restoration or not, I can’t say. But it looks forlorn and not that big and powerful as it looks in videos.
tac Foley said:
As Paul notes - the incredibly damaging blast and raised risk of asphyxiation for the crews of the very large locos on the SP led to the development of the cab-forward locomotive.
More, it was these problems that led the GN to the use of electrics in the Cascade tunnels. Bigger consists meant bigger locos were needed, and although the GN had a great fleet of articulated locos of extreme beauty and power, it was the Z1 and Y1 electric that ruled the long holes through the state.
tac
Ottawa Valley GRSA sad day when the Milwaukee Road and the Great Northern ended their electric operations. Not to mention Conrail, etc. To me, there is nothing like watching those Bi-Polars or Little Joe electrics working. Of course my favorite, GG1’s which I grew up with in and around Philadelphia.