Heisler Tender Frame Design
Nelson Riedel, Nelson@NelsonsLocomotive.com
7/01/2005, last updated 02/24/2007

Update February, 2007:   This page has been updated to reflect changes made when the tender frame was actually constructed.

The photo above shows the lower half of the MRSR91 tender.  The plan is to make the model tender look like this tender with the exception that the model will be about 10% longer and the tank about 10% higher.  The prototype had a wood deck between the tank and deck.  I plan to use a 1/8" steel plate deck. The photo at right shows the underside of a late Heisler tender frame.  The major pieces are the two side castings, the bolster and the two coupler support castings.  The coupler supports bolt to the bolster in the center and the wood sills at the ends.   I plan to use a steel bar on the ends to connect the ends of the sides and the supports similar to the front sill bracket design on the locomotive.  The  frame bolster on the prototype is the same as used on the locomotive whereas a slightly different bolster than the locomotive will be used on the model tender.   All parts will be fabricated from steel plate, bar and angle stock

Tender Frame Side: The drawing above shows the design of the tender frame side.  The two sides are identical except for the position of the holes for the bolster; the bolster is positioned slightly to the rear of the tender middle.  The holes to attach  to the bolster must match up with the mating holes shown on the bolster drawing.  The sketch of the entire frame at the end of this page shows the position of the bolster in relation to the sides.  Note that these sides are very different than the prototype.  However, the only visible part on the finished tender will be the outside edge which looks exactly like the prototype.   The sides will be made up of lengths of 3/16" X 4" bar,  1/4" X 1" X 1"  angle and 3/16" X 1.5" X 1.5" angle.  The one leg of the outer angle will be cut to match the curved profile of the side.  The pieces will be held together by #6 FH screws running from the top down into threaded holes in the angles.  

Frame Bolster: The tender frame bolster shown above is similar to but somewhat simpler than the locomotive bolster.   The main piece is a length of 1.25" X 2.5" HRS bar.   Pieces of 3/16" X 1" bar are welded to the bottom for the pads.  The cylinder that slides into the truck bolster is a piece of 1.875" diameter bar bolted to the main bar.     The plan is surface the bottom and bore the recess in the top on the lathe.  The recess in the top is for a  external retaining ring on the truck pin.  The top of that pin will be below the top of the bolster so as to not interfere with the tender floor.   

Tender Frame Front:  The drawing above shows the tender frame front which is a piece of 1/4" HRS bar.  I'll probably weld or silver solder a couple pieces of 1/4" X 3/16" bar to the edges of a 1/4' X 1.5" bar to achieve the shape shown.  The holes for the #6 screws must align with the ends of the angles on the sides.  Mating holes will be tapped into the ends of those angles.   The 1/4" holes will align with tapped holes in the end of the front coupler support.    There will be a hole in each side which matches with a hole tapped in the upper edge of the front.  The position of these holes is shown on the drawing for the sides.     

Tender Frame Rear:  The drawing above shows the tender frame rear which is simply a piece of 1/4" X 1.5"  HRS bar.  The holes for the #6 screws must aligned with the ends of the angles on the sides.  Mating holes will be tapped into the ends of those angles.   The 1/4" hole will align with a taped hole in the end of the rear coupler support.     There will be a hole in each side which matches with a hole tapped in the upper edge of the rear.  The position of these holes is shown on the drawing for the sides.        

Sills:  The sills are 1.375" X 1.875" X 16" pieces of hardwood.   The plan is to try to get some pieces of maple or cherry for the sills.  While maple and cherry aren't as hard as the oak sill used on the prototype, they have a finer grain which should look more realistic for the model, especially if the sills are stained rather than covered with a thick coat of paint.

Front Coupler Support:  The front coupler support design is shown in drawing above.   The central piece will be made from 1" thick HRS bar stock with the end a piece of 1/4" X 1.187" HRS bar stock.     The end will be screwed and silver soldered to the main bar.

Link Coupler Pocket: The Cass 6 link coupler pocket mounted on the tender front sill is shown on the right.  It would be nice to have a casting of this part but  for just one part, it's not worth the effort.  I'll just have to find a way to machine it easily.
The drawing at right shows the link coupler pocket  design.   I left the dimensions of the attachment holes and the 3/16' thick ribs off because the drawing was becoming too cluttered.  The plan is to machine it from a block of steel or bronze.  The three ribs will probably be made separately and silvered soldered to the main piece after all the other machining is completed.

Rear Coupler Support:  The tender rear coupler support shown above is nearly identical to the locomotive front coupler support.   The support will be constructed of  1" thick and 1/4" thick bar stock.  The plates on the ends will be screwed and silver soldered to the central bar.

Coupler Pocket:  The rear coupler pocket is the same as that used on the front of the locomotive.    See the locomotive frame design information for details. 

The drawing above shows the various pieces of the tender frame all assembled.  The front is on the right.