Heisler Truck Construction I
The Wheels sets and all the gearing were completed several years ago while waiting for the truck castings. The redesigned castings arrived last fall and were immediately attacked with the machinery. Now it's time to go back and show how some of the parts were machined. Unfortunately, some of the photos of the machining process have been deleted. So where necessary, I've remounted a finished piece to show how the machining was done.
Lower Cross: The truck side was set aside to be finished later and the lower cross was machined next. The photo above shows turning the ends of the lower cross. The piece was rotated in the 3 jaw chuck until a spot was found where the the far end was roughly centered as determined by a dial indicator (that area of the casting is rough with a significant parting line). There was insufficient material to make the ends 5/8" diameter so they were turned down to 19/32" and the sleeve bearing was changed from 5/8" ID to 19/32" ID. The shaft end was drilled and tapped and the shoulder at the inner end was turned to the correct dimensions using this same setup.
The photo above shows a finished lower cross with associated parts. When I'm satisfied that no modifications will be required, the end caps will be secured with Loctite (after the bearings are slid onto the shafts).
This shows the HM315 Swivel Bearing Block secured in place by a pair of HM323 Swivel Bearing Block Clamps. These parts are described in the Outside Truck Gears and Shafts section. The original plan was to use a sleeve bearing inside of the bearing block. When I got around to making the block I found some bronze bearing stock scraps left over from making the engine rod bearings so that was used eliminating the need for a separate sleeve bearing. The HM315 drawing has been updated.
Back to the Truck Sides: After the lower cross was completed, the trucks with lower cross and axels were assembled and everything checked to make sure it fit together and verify that the sides were straight. The sides were then removed and the final machining of the sides completed. The image above lists the tasks.
HM206 Bearing Retainer: Slots 1/32" deep by 1/2" wide slots were milled in the truck side at the proper location for the bearing retainer. The bearing retainer was used as a temple to location the holes in the truck side which were then drilled and tapped for the plate attachment screws.
HM207 Upper Cross: The Upper Crosses are simply lengths of 1/8" X 3/8" CFS bar stock with a hole in each end. The ends of the bars fit into the slots shown on the image above. This slots were milled and the cross attachment holes were drilled and tapped at this time.
HC207 Bolster cap Attachment Holes: The Bolster Caps machined earlier were clamped to the truck sides and used as templates to locate the associated attachment holes. The vertical hole for the 8-32 bolt is over 2.5" long ----care must be taken to make sure the side is held vertical in the drill press and the drill pulled out often to clear chips. Drilling a short hole and tapping it requires less effort but has the risk that the attachment screw becomes rusted in place.
Slots for the Brake Shoe Hangers: These 1/4" wide slots were cut using a Woodruff Key Slot cutter. The truck sides were clamped in the milling vise with the side facing up for this operation.
Holes for Brake Shoe Hanger Pins: I made a fixture to locate these holes but have misplaced it so no photo. The fixture has a slot that fits over the bars on the side of the casting. The holes for the pins were drilled all the way through the casting so that a pin rusted in place can be driven out from the inside. Long pins are used to reduced the probability the casting will break if the brakes grab.
This is a good spot to break. The truck fabrication will be continued in the Truck Construction II page.