Wednesday, March 25, 2009

Sand Tower at Marshalltown Yard

From my last post you know that I recently photographed the century old rail yard in Marshalltown, Iowa. What I didn't know was the name of the tower or its purpose as seen on the left side of this photo. All you railroad (RR) old-timers can stop reading now because you already know the answer.

Turns out the structure is called a Sand Tower. Ok, so is that RR slang for a modern diesel fuel depot? Is it a hold out from the old days of coal and steam power? What is the connection between sand and anything to do with railroading? After an unfruitful search on the Internet I found a knowledgeable source and asked the questions.

Evan Werkema, a railroad expert and the web master for the Atchison Topeka & Santa Fe Railway Subjects web site responded with this information about what a sand tower is and why it is named such:

"The name is quite literal - they are towers with a bin at the top containing fine, dry sand, along with hoses for dispensing the sand into sand bunkers on locomotives, and some means of getting sand deliveries up to the bin in the first place. Steel wheels on steel rails are a more fuel efficient way of moving goods compared to rubber tires on asphalt in part because there is less friction between the surfaces. The downside, of course, is that ordinary trains can only climb modest grades, and water or oil on the rail can cause locomotive wheels to slip and potentially make the train stall. To temporarily increase the friction and diminish wheelslip, locomotives are equipped with sanders that blow sand in front of or behind the wheels when the engineer or the locomotive computer system deems it necessary. Most diesel locomotives have sand bunkers at the front and rear that contain a quantity of fine, dry sand, and the bunkers are refilled as needed at sand towers located in locomotive servicing facilities. Some are just a single cylindrical bin atop a metal girder which can serve two locomotives at a time, while others are more complicated "sanding racks" with multiple bins and sets of hoses that can serve multiple locomotives, often in conjunction with ground-level fueling racks."

Evan says that Marshalltown's sand tower is the simple kind, with a cylindrical bin atop a pole, and a diagonal pipe leading over to an adjacent track. Consider yourself informed now. Know that.

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