# Steam locomotive question **URL:** \ **Category:** Factual Questions\ **Created:** [May 24, 2004, 12:30pm UTC](https://boards.straightdope.com/t/steam-locomotive-question/246775 "2004-05-24T12:30:08Z")\ **Posts on this page:** 10\ **Page:** 1
**Author:** ![Princhester](https://avatars.discourse-cdn.com/v4/letter/p/3e96dc/32.png) [@Princhester](https://boards.straightdope.com/u/Princhester)\ **Post date:** [May 24, 2004, 12:30pm UTC](https://boards.straightdope.com/t/steam-locomotive-question/246775/1 "2004-05-24T12:30:08Z")
Tonight my 22 month old pointed to a part on a steam locomotive in a picture book and said: “Mmmm?” which translates as “say the word for what I am pointing to, Daddy” And I realised I didn’t know. Well, there goes my heretofore perfect record (in his eyes) as an infallible fount of all knowledge. Damn. Had to happen sooner or later I suppose. Anyhoo, what is the rounded bump behind the funnel called, and what’s it for? You can see an example in [this](http://www.steamtrain.co.uk/thomas1.JPG) photo of a model of Thomas the Tank Engine. ---
**Author:** ![Algernon](https://avatars.discourse-cdn.com/v4/letter/a/a183cd/32.png) [@Algernon](https://boards.straightdope.com/u/Algernon)\ **Post date:** [May 24, 2004, 1:25pm UTC](https://boards.straightdope.com/t/steam-locomotive-question/246775/2 "2004-05-24T13:25:38Z")
See [this web page](http://home.new.rr.com/trumpetb/loco/locoworks.html) for a good diagram of a steam locomotive and its various parts. [Here](http://www.nps.gov/stea/locowork.htm) is another good site that actually has a photo of a cutaway steam engine. In the cartoon version you link to, the dome represented is the steam dome which contains the throttle. Every locomotive boiler has one of these. Any other domes on top would be sand domes which contain sand to supply to the wheels for traction. ---
**Author:** ![Mycroft\_Holmes](https://avatars.discourse-cdn.com/v4/letter/m/a5b964/32.png) [@Mycroft\_Holmes](https://boards.straightdope.com/u/Mycroft_Holmes)\ **Post date:** [May 24, 2004, 2:01pm UTC](https://boards.straightdope.com/t/steam-locomotive-question/246775/3 "2004-05-24T14:01:17Z")
Well, if you go by this [cite](http://www.nps.gov/stea/locowork.htm), it seems to be either a steam dome or a sand dome. The steam dome is simply where the steam gathers before it is released via the throttle. A sand dome simply stores sand which is dropped onto the tracks via pipes to give more traction. ---
**Author:** ![Mycroft\_Holmes](https://avatars.discourse-cdn.com/v4/letter/m/a5b964/32.png) [@Mycroft\_Holmes](https://boards.straightdope.com/u/Mycroft_Holmes)\ **Post date:** [May 24, 2004, 2:06pm UTC](https://boards.straightdope.com/t/steam-locomotive-question/246775/4 "2004-05-24T14:06:29Z")
And if I had previewed, I would have seen **Algernon** answered (with diagrams too.) :smack: As Algernon says, in the cartoon picture, it is a steam dome. There should normally be at least one sand dome also, but then again, I always thought Thomas the Tank Engine was missing a few parts! For instance, where is the steam chest? Without that, he ain’t goin’ nowhere! ---
**Author:** ![Algernon](https://avatars.discourse-cdn.com/v4/letter/a/a183cd/32.png) [@Algernon](https://boards.straightdope.com/u/Algernon)\ **Post date:** [May 24, 2004, 2:15pm UTC](https://boards.straightdope.com/t/steam-locomotive-question/246775/5 "2004-05-24T14:15:33Z")
> [@Mycroft Holmes](#): > > I always thought Thomas the Tank Engine was missing a few parts! For instance, where is the steam chest? Without that, he ain’t goin’ nowhere! Good point. I didn’t notice that. But then I never read _Thomas the Tank Engine_ when I was little, nor read it to my kids. When I was a little kid, the book I read over and over was [Tootle.](http://www.amazon.com/exec/obidos/tg/detail/-/0307020975/qid=1085407893/sr=1-1/ref=sr_1_1/104-3044642-3795964?v=glance&s=books) As you can see from the cover illustration, _Tootle_ does have a steam chest. ---
**Author:** ![Rob76](https://avatars.discourse-cdn.com/v4/letter/r/5e9695/32.png) [@Rob76](https://boards.straightdope.com/u/Rob76)\ **Post date:** [February 1, 2022, 10:49pm UTC](https://boards.straightdope.com/t/steam-locomotive-question/246775/6 "2022-02-01T22:49:35Z")
I need some insight please I am an author that is currently working on my second book. It is taking place in 1937 West Virginia mountains. The passenger train tops the mountain. Upon slowing entering into a steep 10 mile downgrade the engineer realizes the brakes are failing. What is left to do save the more than 100 passengers aboard? Is throwing the locomotive in reverse while in a forward motion a viable option? ---
**Author:** ![CookingWithGas](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cookingwithgas/32/485_2.png) [@CookingWithGas](https://boards.straightdope.com/u/CookingWithGas)\ **Post date:** [February 2, 2022, 2:55am UTC](https://boards.straightdope.com/t/steam-locomotive-question/246775/7 "2022-02-02T02:55:53Z")
> [@Rob76](#): > > I need some insight please You are replying to a thread that is almost 18 years old. You should probably start a new thread with your question. ---
**Author:** ![Aspenglow](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/aspenglow/32/76_2.png) [@Aspenglow](https://boards.straightdope.com/u/Aspenglow)\ **Post date:** [February 2, 2022, 4:23am UTC](https://boards.straightdope.com/t/steam-locomotive-question/246775/8 "2022-02-02T04:23:51Z")
The question was well answered in this thread by @Francis_Vaughan: > [@Steam trains](https://boards.straightdope.com/t/steam-trains/944265): > > I’ve noticed that on a lot old stream trains there is bell looking device on top of the smokestack. Does it serve a purpose, or is it decorative? [[image] ](https://i1.wp.com/www.denverpost.com/wp-content/uploads/2017/08/ap17237525355665.jpg?w=620&crop=0%2C0px%2C100%2C9999px) I’m closing this thread pending further review by FQ mods. ---
**Author:** ![Aspenglow](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/aspenglow/32/76_2.png) [@Aspenglow](https://boards.straightdope.com/u/Aspenglow)\ **Post date:** [February 2, 2022, 4:24am UTC](https://boards.straightdope.com/t/steam-locomotive-question/246775/9 "2022-02-02T04:24:04Z")
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**Author:** ![engineer\_comp\_geek](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/engineer_comp_geek/32/504_2.png) [@engineer\_comp\_geek](https://boards.straightdope.com/u/engineer_comp_geek)\ **Post date:** [February 2, 2022, 9:01am UTC](https://boards.straightdope.com/t/steam-locomotive-question/246775/10 "2022-02-02T09:01:02Z")
Considering that this latest addition is off-topic for the original thread, and was answered in the thread that @Aspenglow linked to, I think it’s best to leave this closed.