NPC 21 Tender

Number 21 had a most unusual tender.  Dominating features are a vertical drum tank for oil and another vertical drum tank for water.


This shot shows the tender from the engineer’s side of the engine.  Things are notable about this photo:

  1. Note the gauge on the top of the front (oil) tank.  Keith speculates that the gauge is measuring air pressure.  He indicates that given the quality of oil in those days, heat was necessary to get the oil to flow and combust properly.  So a steam line was likely to be coiled at the bottom of the tender.  But given the presence of the large air tank immediately behind the oil tank, it is likely the oil was pushed with air pressure.  The device next to the air gauge is likely to be a pressure regulator.
  2. A line running from the back along the tender sill.  It drops down then rises to the underside of the running board.  Note the valve to shut off the supply sticking up at the junction between the horizontal portion of the line and the portion that drops into a loop to the engine.  This line appears to rise to the underside of the running board where it is likely to run underneath the board to the engine.
  3. A line that runs along the top of the deck then rises out of site.  It appears to start in the area of the larger vertical air tank between the oil and water tank.  This is likely to be the air line headed toward the air compressor mounted on the engineer’s side of the engine.  Also note what looks to be a drain plug on the bottom of the air tank.  this would be used to drain condensate.  Click here for a diagram of a Westinghouse Air Brake system.
  4. Note also the vertical line beginning 2/3 the way up the side of the water tank.  It drops down to the deck.  What is the purpose of this line?  Water would be taken off near the bottom of the tank.
  5. Note the smaller tank located behind the larger tank noted in item 3.  Is this tank an air pressure regulator for the air brake system?


This shot views the tender from the fireman side.  Things that are notable about this photo:

  1. Note that the water tank appears to be significantly larger in diameter than the oil tank.  Not only does it appear wider, it also hangs over the edge of the deck.
  2. A line very similar to the line in item 2 in the previous photo appears on this photo.  It runs along the side of the sill back into the area of the water tank.   Keith indicates that redundant water lines were a common practice should one of the lines become clogged.  Note that you can see the continuation of this line running underneath the running board.
  3. A line also appears to come out of the side of the oil tank.  Note the shutoff valve.  It would also appear to run below the running board.  It is likely this is the oil line as the firemen is seated on this side of the engine.
  4. A container is located between the oil and water tank.  You can faintly see hinges on the left side, a door, and a latch on the right side.  This appears likely to be a tool box.
  5. A ladder appears to run up the back of the water tank to the top of the tank.
  6. A fill chute and cover appears to rise from the top back of the oil tank and the top front of the water tank.


This photo shows the tender from the engineer’s side.  Things that are notable about this photo:

  1. The rear water tank overhangs the deck on this side too.  That’s further verification that the water tank was larger than the air tank.
  2. In this view the water line appears to come from underneath the water tank.  In this photo it can be seen running beneath the running board.
  3. Note the gauge.  The device to the left of the gauge is likely to be an air pressure regulator.
  4. The line that appeared to begin 2/3 the way up the water tank also appears in this photo.  Is it coming off the top of the small tank instead?  The purpose of this line and device remains unclear.


This photo is also from the engineer side of the tender.  Things that are notable about this photo:

  1. The hatch allowing the water tank to be filled also appears on this photo.
  2. There is a vertical fitting on the top left of the oil tank.  Is this the filler?


This photo is of the firemen side of the tender.  hings that are notable about this photo:

  1. Note the top and what appears to be a lock on the box between the oil and water tanks.  It is likely to be a container for tool storage.
  2. Once again, the redundant water line appears in the photo.



Tender in the first two drawings are seen from the back.  The ladder appears on this drawing as well as the water tank hatch.


This Elmer Wood side drawing shows the water and oil tank hatches and the tool box.Note that only two lines are drawn between the engine and tender.  it is likely there were five.

  • Two water feed lines.
  • An oil feed line.
  • A line carrying steam to the oil tank.
  • An air line from the compressor to the air tank.

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