Steam engine question

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I think some also had blowers to bring in air but could be mistaken. As far as interesting facts are concerned , Steam locos were very hard on the rails. The side rods thrashing back and forth and cylinders moving them caused a right left motion which was detrimental to the track.

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You are actually quite correct. All steamers had what was called a blower. It was controlled, among other things, by the fireman. When the engine is first getting heated up to operating temperature, the flues are cooler than when the engine is the hottest and working hard with exhaust steam venting up the blast pipes, through the petitcoat pipe, and up the stack. Cooler flues, like cool chimneys, don't draught well.

With a decent fire going and gew pounds of pressure in the boiler, the hostler turns a valve and lets steam out through a pipe just under the stack, facing up. That is the blower. When an engine is stationary and not chuffing, the blower is almost essential, even if only just barely going. It helps to keep the fire healthy. The blower can be turned off when the engine is underway, and certainly when it is straining under a load. As stated by another gentleman, a fire that is worked too hard, and at the same time not carefully groomed for depth by the fireman (if coal fired), would result in areas of the coal bed literally ripped up and sucked through the flues. What would be left are holes which would allow cool incoming air an easier path into the flues. Cool air cools the flues causing rapid differential strain against the welds in the bulkhead. This could break welds and cause high temperature water and steam to enter the firebox.

Not good.