Heisler Truck Design II
Nelson Riedel, Nelson@NelsonsLocomotive.com
3/17/2005, last updated 01/30/2010

Update 1/29/2010:  This page was updated to show the actual truck side casting and to show that the axel bearing cap and lower cross cap will be machined from bar stock instead of cast as originally planned.

The main truck side casting, axel bearing cap and  cross piece retainer are the subject of this part.  Before starting the design of the truck sides the following photos of disassembled trucks were reviewed. .

The partially disassembled truck above has the truck bolster and the upper cross pieces which hold the truck sides in place.  This is a later truck design which has a much simpler upper cross pieces than used on Cass 6.  The brake plank which holds the brake cylinder is used only on the outside trucks.

The photo above gives a clearer views of the inside of the truck side casting.  This is a middle truck where the brake cylinder is attached to truck side by the bracket identified on the drawing.   The brake cylinder is barely visible in the weeds.   The lower cross piece is still installed on this truck.  The bearing for the gearbox swivel on the lower cross piece is off center, another clue that it is the middle truck where the gear case and pinion shaft are off center to one side to make room for the line shaft on the other side.

The  photo above shows a lower cross piece with the shaft on the left side is broken off.  The non symmetric center indicates that it is for a middle truck.

This shows the bottom  of the truck side where the shaft from the lower cross fits.  The black stuff in the center might be hardened grease. Note the shoulder on each side of the of recess used to align the cap. (I had wondered how I was going to align that cap.)

This shows the under side of another truck side with the lower cross cap in place.   The cap is held in place by four bolts fed through the bottom of the spring cavity area.   The bolt heads are visible on several of the previous photos. If you're wondering why I didn't lift the truck side up out of the weeds before taking the photo all I can say is I tried.  But, hadn't eaten my Wheaties.    That side probably weighs at least  500 pounds.

Photo above shows the part of the truck side between the wheels.   Sorry about the bright light across the top.   It was a chilly morning and the sunshine was welcome.  The brake hangers are held by pins at the top.   The flat cross bar above the brake shoes keep the hangers and shoes aligned with the tire treads.

Truck Side HC202: The drawing drawing above shows the truck side which will be cast in iron.   

This is a photo of three truck side castings. 

Lower Cross Cap HM210:  The shafts on each end of the lower cross piece are clamped to the truck sides with the lower Cross Cap shown in the drawing on the right.     The cap attaches with four socket head cap screws. The Lower Cross Cap will be machined from mild steel, cast iron or aluminum.  The holes in the cap can be used as a template to located the mating holes in the truck side.
Axel Bearing Cap HM211: The axel bearing cap  is shown on the right. The cap and mating recesses in the truck side are  machined to match the bearing OD plus a margin of 0.015".  The margin is to permit the truck side to flex to match track variations. The Axel Bearing Cap will be machined from mild steel, cast iron or aluminum. The bearing cap can be used to locate the screw holes in the truck side.
The axel bearing hole in the truck side has no shoulder or retaining ring to simplify the the casting and subsequent boring of the holes.  The bearing retainer plate shown on the right is attached to the outside of the truck side casting to retain the bearing within the side.  The retainer plate is simply a  2" length of 1/2" X 1/8" CRS stock.   The plate fits into a 1/32" deep slot milled into the truck side.

The remaining truck parts are described in Truck Design Part III.