two questions about steam

[nw-mailing-list at nwhs.org]

This is in reply to the second question.

To appreciate how well the N&W designed its tenders, one must look at other railroads' tenders. Using the figures below, the 135,320 pounds of empty weight carried 183,260 pounds of coal and water. That is a ratio of 1.8 pounds of coal and water for each pound of the tender.

A review of tenders of about 20 other railroads is very revealing concerning their empty weight and carrying capacities. All carried between 1.2 and 1.5 pounds of coal and water for each empty pound. The N&W designed its tenders to carry more in relation to its dead weight than the others. What the N&W did was about the limit for two three-axle trucks. To go to a four-axle truck or to the centreped bedcast tenders meant a significant increase in dead weight without any significant increase in the amount of coal and water carried.

The 67 tons is quite good. In 1955 when the N&W added coal boards to its tenders, this added five more tons of coal. So the N&W actually added more coal carrying capacity without adding any significant weight. This is good design work.

Bud Jeffries
  ----- Original Message ----- 
  From: nw-mailing-list at nwhs.org 
  To: nw-mailing-list at nwhs.org 
  Sent: Saturday, February 25, 2006 11:25 AM
  Subject: two questions about steam


  Hi Guys,

  Have a question about the grade or size of coal pieces used in engines equipped with automatic stokers like the Y, A, and J.  The reason I'm asking is that I'm trying to convince a certain brass designer/importer of O scale models that his simulated coal loads are incorrect (other than that, the one model of his I own is great).   On my Y6a, the coal chunks look to be a good six scale inches across.  My limited understanding is that high pressure air was used to distribute the coal across the firebox.  Pieces 6" across just couldn't be propelled by air.  Pictures I've seen show a much finer grade.

  The second question relates to the locomotive weights given in one of the appendices to Jefferies' "Giant of Steam".  Total weight of the Y6b including tender is listed as 990,100 lbs, and 611,520 lbs without tender.  So tender alone would be 378,580 lbs.  22,000 gallons of water weighing 8.33 lbs/gallon would weigh 183,260 lbs, and adding 30 tons of coal would make the total load 243,260 lbs.  This would make the empty weight of the tender 135,320 lbs, over 67 tons, which seems very heavy, since I don't see how any mechanical advantage could be gained by adding weight to the tender.

  Thanks in advance for your ideas.

  Tom Leuthner


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