Cass 6 Main Frame III
 Nelson Riedel, Nelson@NelsonsLocomotive.com
6/24/2004, last updated 04/08/2006

The details of the rear part of the main frame are presented in this part.  The topics discussed are:

  • Rear Bolster

  • Rear Bolster  Bracket

  • Rear Sill

  • Rear Center Casting

  • Cross casting

  • Boiler Supports

  • Frame Channels

  • Jacking Points  

The photo above taken from the firebox area looking to the rear shows the rear part of a Heisler frame.   This is a much lighter locomotive than Cass 6 and some of the castings differ considerably from those of Cass 6, but the basic configuration is the similar.    

Rear Frame Bolster: The rear frame bolster (for the middle truck) appears to be nearly identical to the front frame bolster.   The only difference I noted was that the bolster clamps to only the lower frame side bar instead of both bars.  As a result, the sides are 4 inches shorter  and there are 8 instead of 13 bolts securing each side.       

 

Rear Bolster Bracket:  I was unable to get an unobstructed photo of the rear bolster bracket.   However, this photo gives a good bit of information.  The bracket is 9" high and clamps only the lower frame bar.  The bracket also serves as a support for the frame side channel.  The bolts through the frame side bar are  accessed through the hole in the bracket  
The outside dimensions of the bracket shown on the drawing are accurate.  However, the size of the opening is an estimate.   

 

Rear Sill: The rear sill is a casting.  The photo above shows the view from the back (tender is disconnected) with the link that connects to the tender.  

The photo on the right taken from the left side of the locomotive shows the underside of the rear center frame casting and the rear sill.   It can be seen from the photo that the sill has hollow sections. 
This shows how the lower frame side bar and the frame channel attach to the sill. The pipes, oil and corrosion make it difficult to see the structure.   However, a little study reveals considerable detail.  
The outside dimensions of the sill as shown on the drawing are accurate.  However, as noted, the structure of the hollow interior is a guess.. 
Frame Rear Center Casting: The rear center casting connects between the rear sill and the rear bolster.  It also contains a pocket for the link coupler swivel shown in the photo. The pin through the disk also passes through the coupler link thus pinning the link to the disk.  The disk allows the link to swivel.  There is a gap between the disk and the pocket so the link can move side-to-side.    
The drawing of the Frame Rear Center Casting
Frame Cross Casting: The frame cross  casting is positioned between the rear bolster and the back of the firebox.   The casting is T shaped with the top of the T spanning the frame sides and the base of the T connecting to the center of the rear bolster. This is a good photo showing that the casting is open at the bottom.  

There are two bolts between each side of the casting and the lower frame side bars.   The bolts heads are obscured by dirt and grease.  
After checking on this castings several times I finally got the dimensions correct ---- I hope.
Front Boiler Support: The front of the boiler is supported by the smoke box saddle.   The rear is supported by four boiler support castings; one under each corner of the firebox.   These supports are bolted to the lower frame bars.  The boiler sets on the supports and is free to slide front to back to accommodate expansion and  contraction.    This is a photo of the right front support.    
This shows the edge of one of the supports.   A 1" X 5" bar sides into the slot in each supports.  One bar crosses between the front supports and another between the rear supports.     

Drawing of the front support. 
Rear Boiler Support:   This shows the left rear support and is taken from behind.  The steel cylinder is the top of a jack ---- the rear of the locomotive was on jacks so that the middle truck could be removed.      The rear supports are nearly identical to the front supports .  The main differences are that part directly under the boiler is more robust and the wings under the frame extend further to the front and rear and have the triangular support piece. 
A bracket  bolts to the top of the rear boiler support  that connects to and supports the channels discussed next.   The channel is visible in the previous photo.   This bracket is not shown on the adjacent drawing of the rear boiler support.   

 

The last major pieces of the frame are the channels that support the cab.  The channels are 8" X  2.25" and  set out 13" from the frame side bars.  This photo shows the front edge of the left channel.   That is a plate that supports the front of the channel.  The plate connects to the frame and the channel via angles.  The channels are also support by the rear boiler supports, the bolster brackets and the rear sill.  There is a 4" wood spacer on top that supports the cab floor.  

 

Jacking Pad:  This fixture on the on the lower fame bar just behind the front truck appears to be a jacking pad.   An earlier photo shows a jack under one of the rear boiler supports.  This pad could fill the same role to raise the front of the frame so that the front truck could be slid out.    

 

The drawing above was made by pasting the individual frame piece drawings together on a drawing of the side bars.  Everything fits together --- a miracle!  I considered doing a side view but decided to quit while ahead.    All the main frame drawings are combined into one file that can be downloaded from the Drawings page.

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