Heisler Truck Construction II
Nelson Riedel, Nelson@NelsonsLocomotive.com
1/30/2010, last updated
01/30/2010

The machining of the truck bolster and associated components as well as the fabrication of the truck side rod are described in this page.

Photo above shows the bottom view of the assembled truck at this stage ---- no brakes and no rods.

Photo above shows the top view of the truck at this stage.  This is the tender truck (outer truck gearing and no axel pump).  The tender truck carries the heaviest load and uses a total of 8 springs --- the other two trucks use only 6 springs each.    The major remaining part is the Truck Bolster.

HC206 Truck Bolster Casting: The photo above shows a finished bolster with rollers and bolster pin installed.   The first step in the machining is to center the casting in the lathe 4-jaw chuck and drill and bore the recess in the center.  The bolster pin can then be installed and the fit with the fame bolster checked. The pin was turned 0.01" undersize so that the truck bolster could rock slightly with respect to the frame bolster.  The top of the pin was marked with respect to the top of the frame bolster and the end of the pin was then finished for the retaining clip or pin.

The next step was to machine the bolster sides to fit with the bolster cap and to machine the ends to mate with the truck sides.  There is considerable excess material in these area so an approach of sawing off most of the excess followed milling or grinding any that remains is probably the quickest.   I found an easy way to mill the 45 degree angles was to rotate the milling vise 45 degrees and machine the sides with the side of an end mill.   If the trucks are set up at this point with axels, sides and both the lower and upper crosses, one should be able easily check the bolster and continue the machining until it can slide up and down without interference (springs removed).     

HM213 Bolster Roller Base:  The Roller Base is made of 3/16" angle iron and a 1/4" thick bar for the outer support silver soldered together.   The recess in the middle was machined with a Woodruff Key Slot cutter before that outer support was added.  A slot was milled where that support fits and a screw run into the support from the bottom to hold the support in place during the soldering process.  
Recall that the bolster casting had supports as part of the casting. These were sawed off and a recess was milled in the ends of the bolster where the roller base fits.   This photo shows that slot on the end of a truck bolster.
This shows the base held in place with a 10-32 FH screw. 
This photo shows the HM205 Roller and the HM206 Roller Pin which were machined per the drawings in the design section.
This photo shows the end of the truck bolster with bolster cap in position.   The long vertical 8-32 screws were left extra long so that they could be used to draw the bolster cap down against the spring force.  A clamp can be used if the screws are too short.  The horizontal screws are inserted after the cap has been drawn down against the truck side.

HM209 Side Rod: The side rod design drawing is repeated above. The initial plan was to have the rods investment cast in steel.  The foundry I'm using now doesn't cast in steel so it was decided to make the rods from bar stock.   

 

The drawing above shows how the rods were made from three pieces----- the basic rod cut from 1/4" X 7/8" bar stock and the pair of hubs turned from 7/8" diameter bar stock.   The hubs were silver soldered into the rod.   The last thing was to drill and tap holes for the grease nipples and then to install the nipples.

Photo above shows a nearly finished rod.   The edges need to be rounded a bit and the fillets at the interface between the straight and round part of the rod ends need a bit of smoothing.     

This wraps up the truck construction except for the truck part of the brake system which is described in the Heisler Truck Construction III page.

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