Smoke deflectors (also known as smoke baffles, smoke lifting plates, and/or "elephant ears") are metal plates that are attached to the sides of the smoke box on a steam locomotive. In the first half of the 1800s , the trains had very tall chimneys. There was no problem with the smoke. But when trains became larger; new lower, stronger bridges were built (not just for trains). This meant that tall chimneys were no longer an option. This brought its own problems like draft issues, but more importantly smoke was able to get down to the cabs much easier. This was fixed by installing smoke deflectors.
How it worksEdit
When a steam locomotive is moving forward, the air in front of the train is forced against the smoke box and its door. This air is then 'spread' apart and creates a partial vacuum around and behind the edge of the smoke box. The 'spread' air then creates swirling currents that draw down the smoke and block the drivers view forward. This is fixed by physically stopping the air from creating the partial vacuum. By putting the smoke deflectors on the sides of the smoke box, the 'spread' air is forced backwards by the oncoming air. The curved top to the smoke deflectors channels the air into an updraft, the updraft is created by the convection of the hot exhaust, which lifts the smoke from the chimney away from the drivers forward view. So smoke deflectors don't actually deflect the smoke, rather they deflect the air.
- Locomotives in Africa mainly use smoke deflectors, which are commonly known or nicknamed, "elephant ears", because of their size, and because of elephants living throughout the continent. (Aside from it also being a nickname eventually inherited by railfans.)
- The first locomotive in the UK to have smoke deflectors installed was the Southern King Arthur class Sir Percivale, in 1927.
- ALCO's FEF Series of steam locomotives owned by the Union Pacific were equipped with smoke deflectors for their high-speed trains.
- Garratt-Mallet type steam locomotives were originally equipped with smoke deflectors for use in Africa, even though the locomotives ran at slow speeds which caused the need to be unnecessary. Hence, newer-built Garratts weren't equipped with "Elephant Ears".
Book: The Railway Data File published by Silverdale Books. ISBN: 1-85605-499-3.