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Re: SP NG Diesel #1 (GE 50T) - Triennial or Bust

Posted: Mon Apr 16, 2018 1:53 pm
by rkcarguy
Best way to explain it, have a look a BDD's post here:

http://www.chaski.org/homemachinist/vie ... 7&start=36

About halfway down the page, you can see the pictures of his truck setup with the bearings on angle brackets near the groups of 4 silver bolts, and the self aligning pillow block he used for his pivot point for his truck. A few pictures down, you can see the steel pad on the underside of the locomotive frame that the bearings ride on.

"The two small ball bearings—lateral roll bearings—on the truck bolster make contact with wear pads on the underside of the frame. The center bearing is shimmed relative to the bolster so that a very small amount of contact between the lateral roll bearings and the frame is maintained at all times. Hence the truck is free to swivel and longitudinally roll relative to the frame, but cannot laterally roll. Any lateral roll that occurs with the unit is due to movement of the wheelsets in the truck frame pedestals, which is resisted by the springs. The result is that the truck can easily follow abrupt changes in track height, such as might be encountered when moving the unit from a transfer table to a lead track, yet maintain good lateral stability."

All credits and genius status for this design go to bigdumbdinosaur :D

Re: SP NG Diesel #1 (GE 50T) - Triennial or Bust

Posted: Mon Apr 16, 2018 3:20 pm
by senorgilamonster
I have been following that build since I love F7s. So I went back and looked at the pix when you brought it up - and didn't quite get it. Looking again, I am still not getting the center bearing part (big dumb me).. Is it like this? If so, I don't see the advantage, so I must be missing something.

Re: SP NG Diesel #1 (GE 50T) - Triennial or Bust

Posted: Mon Apr 16, 2018 4:51 pm
by rkcarguy
The self-aligning bearing does everything you need, it rotates and swivels. No bronze bushing needed. Using only that however, the train would be free to flop side to side. BDD mounted additional bearings on angle tabs on the bolsters at each side, so that the truck can still swivel but doesn't allow the frame to lean side to side. So to your sketch above, add a bearing with angle supports to each side, with a bolt through it's center in a horizontal plane.

Re: SP NG Diesel #1 (GE 50T) - Triennial or Bust

Posted: Mon Apr 16, 2018 5:41 pm
by rkcarguy
truck.jpg
Lets try this.

Re: SP NG Diesel #1 (GE 50T) - Triennial or Bust

Posted: Mon Apr 16, 2018 6:09 pm
by rkcarguy
I never had the luck of seeing an F7 in person sadly, so I don't have much desire to build one for whatever reason. The stuff occupying the tracks when I was a kid was GP's and SD's, SW's, and the rare Baldwin Switcher(I saw an SP S-12 when I was young, in tow in another train going north). I barely remember one of the few great northern trains I saw when I was very young, I want to say the locomotive was a U25 or U33, blue/white paint and the flat nose. I also remember that was the days of jointed track, and the 40' coal hoppers headed to fire Everson, WA's power plant would rock back and forth so badly that my mother backed up further away from the crossing as we were watching this same train.

Re: SP NG Diesel #1 (GE 50T) - Triennial or Bust

Posted: Mon Apr 16, 2018 6:43 pm
by senorgilamonster
I was a kid at the end of the transition era so F7 and SW1500 was what I remember.

I got the part about the bearings on the bolster sides, but I am still struggling with the center pivot point What is this:

Re: SP NG Diesel #1 (GE 50T) - Triennial or Bust

Posted: Tue Apr 17, 2018 10:20 am
by rkcarguy
That appears to be a threaded insert welded to the bolster and the head of a bolt, he opted to mount the pillow block on his chassis instead of the bolster. If you've got the side bearings figured out, I would just mount the pillow block/self aligning bearing to the bolster and then put a bolt through it from the frame. You'll likely need a little bit of a spacer on each side of the bearing at the bolt to get the right height and allow the bearing to swivel in the block.

Re: SP NG Diesel #1 (GE 50T) - Triennial or Bust

Posted: Tue Apr 17, 2018 2:23 pm
by senorgilamonster
thanks RK

My new phone finally arrived, so pics sill be coming again.

I've cut all of the parts for the second truck frame and discovered Muriatic Acid for removing mill scale. Welding day coming up.

I also cut out the remaining 4 equalizer bars. Here I am using the "grinder as a metal saw" method which is working quite well for me:

Re: SP NG Diesel #1 (GE 50T) - Triennial or Bust

Posted: Wed Apr 18, 2018 4:32 am
by Harold_V
senorgilamonster wrote:
Tue Apr 17, 2018 2:23 pm
discovered Muriatic Acid for removing mill scale.
If you are not familiar with handling Muriatic (hydrochloric acid), be advised that storing it indoors will pretty much guarantee rust on all ferrous objects, regardless of how well you think the container is sealed. Keep it outside, away from vents, windows and doors.

H

Re: SP NG Diesel #1 (GE 50T) - Triennial or Bust

Posted: Wed Apr 18, 2018 10:22 am
by rkcarguy
That's great, I was wondering what happened to your pictures.
I am probably going to supersize the same truck setup, and use some 3/4" flanged pillow blocks for the bolster pivots and bronze bearings on 1/2" bolts with angle brackets on both sides of the bearing for my locomotive and my heavy hauling bulkhead flat cars.

Re: SP NG Diesel #1 (GE 50T) - Triennial or Bust

Posted: Wed Apr 18, 2018 12:42 pm
by senorgilamonster
Harold - thanks for pointing that out. I'm already doing that + wearing gloves, eye protection, etc...but a good remainder for all

Re: SP NG Diesel #1 (GE 50T) - Triennial or Bust

Posted: Wed Apr 18, 2018 5:59 pm
by rkcarguy
Agreed, it's nasty stuff. My dad uses it for removing piston deposits from cylinders and it basically eats the aluminum out of them. Handle it with hazmat gear!