12" working railroad

Discuss park gauge trains and large scale miniature railways having track gauges from 8" to 24" gauge and designed at scales of 2" to the foot or greater - whether modeled for personal use, or purpose built for amusement park operation or private railroading.

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Topics may include: antique park gauge train restoration, preservation, and history; building new grand scale equipment from scratch; large scale miniature railway construction, maintenance, and safe operation; fallen flags; track, gauge, and equipment standards; grand scale vendor offerings; and, compiling an on-line motive power roster.
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BigDumbDinosaur
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Re: 12" working railroad

Post by BigDumbDinosaur » Thu May 28, 2020 4:32 pm

rkcarguy wrote:
Thu May 28, 2020 1:53 pm
On my bulkhead flats there will be no access from the top of the frame though, so I'm kicking around welding a nut into the frame and then leaving a spot so I can cotter pin the bolster bolts.
My F-unit is the other way around: the bolster bolt (actually, a 1/2"-20 socket screw) is accessible from the top. I torque it to 110 lb/ft to make sure it stays tight. The socket screw's head acts to limit how far the truck can pivot from being parallel to the frame if one end of the unit is lifted off the track.

P1010045.JPG
#2 End Truck Mounting
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rkcarguy
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Re: 12" working railroad

Post by rkcarguy » Thu May 28, 2020 4:57 pm

BigDumbDinosaur wrote:
Thu May 28, 2020 4:32 pm
rkcarguy wrote:
Thu May 28, 2020 1:53 pm
On my bulkhead flats there will be no access from the top of the frame though, so I'm kicking around welding a nut into the frame and then leaving a spot so I can cotter pin the bolster bolts.
My F-unit is the other way around: the bolster bolt (actually, a 1/2"-20 socket screw) is accessible from the top. I torque it to 110 lb/ft to make sure it stays tight. The socket screw's head acts to limit how far the truck can pivot from being parallel to the frame if one end of the unit is lifted off the track.
P1010045.JPG
The locomotive and riding car will be like that, but I don't want to have to remove the 5/8" tongue and groove decking from the bulkhead flat cars to access the bolt/nut, so I've got to do something different there.
Because I installed my spherical bearing into the bolsters instead, the diameter of the bolster bolt itself is what limits the pivoting action of the trucks. I may have to make a collar or bump stop of some sort to limit this, there is a lot of movement and the wheels get into the frame well before anything binds.

0351
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Re: 12" working railroad

Post by 0351 » Fri May 29, 2020 8:02 am

BDD- I went thru your F- unit build page, and it looks like you bolted the flange bearing to the locomotive frame, versus bolting the bearings to the truck bolster? Correct?

I’m trying to understand your reasoning for that?

I have been considering fabricating a spherical bearing housing and welding it to the truck bolster, then placing a space washer on it and dropping a bolt down from the bolster beam on the car frame thru the bearings.
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rkcarguy
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Re: 12" working railroad

Post by rkcarguy » Fri May 29, 2020 12:00 pm

0351 wrote:
Fri May 29, 2020 8:02 am
BDD- I went thru your F- unit build page, and it looks like you bolted the flange bearing to the locomotive frame, versus bolting the bearings to the truck bolster? Correct?

I’m trying to understand your reasoning for that?

I have been considering fabricating a spherical bearing housing and welding it to the truck bolster, then placing a space washer on it and dropping a bolt down from the bolster beam on the car frame thru the bearings.
When using a 2 bolt self-aligning flange bearing they can be bolted to the bolster and then the spherical motion loosened up a touch with a flap wheel. Then you just need to add some bump stops somewhere along the line if you are concerned with having a lot of travel, which would really only be an issue in a derailment.
I've been through BDD's F-unit build page as well, with the hydraulic motors being down inside his trucks with disc brakes and all I think they were very crowded and it made more sense to chassis mount his spherical bearings.

0351
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Re: 12" working railroad

Post by 0351 » Fri May 29, 2020 4:05 pm

rkcarguy wrote:
Fri May 29, 2020 12:00 pm
0351 wrote:
Fri May 29, 2020 8:02 am
BDD- I went thru your F- unit build page, and it looks like you bolted the flange bearing to the locomotive frame, versus bolting the bearings to the truck bolster? Correct?

I’m trying to understand your reasoning for that?

I have been considering fabricating a spherical bearing housing and welding it to the truck bolster, then placing a space washer on it and dropping a bolt down from the bolster beam on the car frame thru the bearings.
When using a 2 bolt self-aligning flange bearing they can be bolted to the bolster and then the spherical motion loosened up a touch with a flap wheel. Then you just need to add some bump stops somewhere along the line if you are concerned with having a lot of travel, which would really only be an issue in a derailment.
I've been through BDD's F-unit build page as well, with the hydraulic motors being down inside his trucks with disc brakes and all I think they were very crowded and it made more sense to chassis mount his spherical bearings.
Understood. I’ll build this car with the flange bearings and side bearings see how it works out. I realize that design may change thru out this build, however I do want to stay with the same setup with the other 3 cars.
Bearings came in!
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0351
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Re: 12" working railroad

Post by 0351 » Fri May 29, 2020 5:30 pm

Ryan, regarding your locomotive trucks, did you drill a center hole thru the truck bolster for the bolt/pin?

Looks to me, unless I drill the bolster hole bigger than my 1” bolt, it won’t allow the truck to pivot and n the bearing.

I hate to drill big hole in my 3”x3/4” bolster bar. Seems it would cause integrity failure strength wise?
Lol! Guess I’m hijacking your thread a should start mi own. However at the rate I’m getting stuff done it be far in between post.
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rkcarguy
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Re: 12" working railroad

Post by rkcarguy » Fri May 29, 2020 5:46 pm

0351 wrote:
Fri May 29, 2020 5:30 pm
Ryan, regarding your locomotive trucks, did you drill a center hole thru the truck bolster for the bolt/pin?

Looks to me, unless I drill the bolster hole bigger than my 1” bolt, it won’t allow the truck to pivot and n the bearing.

I hate to drill big hole in my 3”x3/4” bolster bar. Seems it would cause integrity failure strength wise?
Lol! Guess I’m hijacking your thread a should start mi own. However at the rate I’m getting stuff done it be far in between post.

It's no biggie you hijacking the thread here and there don't worry about it.

I have a few different setups. On my locomotive trucks I used 3/4" bearings like the ones on your picture, and used 3" channel for the bolsters so drilling a clearance hole for the through bolt didn't effect the strength any.
On the riding car I used 2x1 tube bolsters with collars welded to them for spherical bearings to press into, and for the bulkhead flat car trucks I used solid 2x1 bar with a drilled hole and a counterbore for the spherical bearings to press into.

The nice part is that with the "standoff bearings" taking the load closer to the ends of the bolsters, the bolster pin is merely a pivot point and just has to be strong enough to put up with any lateral forces from braking or derailments so you should be fine with a clearance hole in the 3/4" bar say 1-1/4" diameter which will allow your bolt to pass through and also limit the amount of pivot to a reasonable amount. If you're worried about it and have welder access, you can add some gussets on either side to make a "channel" around the flange bearing and beef it up a little but I don't think its needed. Real freight cars actually use a similar setup, they have big slide bearings out closer to the truck side frames that pivot on the chassis and distribute the load. If they didn't, I think the tonnage they put in them would easily break the bolster forging at the pivot pin.

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BigDumbDinosaur
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Re: 12" working railroad

Post by BigDumbDinosaur » Fri May 29, 2020 7:58 pm

0351 wrote:
Fri May 29, 2020 8:02 am
BDD- I went thru your F- unit build page, and it looks like you bolted the flange bearing to the locomotive frame, versus bolting the bearings to the truck bolster? Correct?
Correct.
I’m trying to understand your reasoning for that?
The way I arranged it means the center bolt can be threaded into the truck bolster without having to get access to the underside of the bolster. Were it the opposite, I'd have to remove the traction motor in order to get to the center bolt. Not only that, there would have to be a nut on the top side of the bearing hub to secure the center bolt. Also, I'd have to maintain some clearance for a bolt head, which means the traction motor would be lower in the truck, which introduces a couple of problems related to roller chain geometry and clearance over the rail head.

With the bolt threaded in from the top, the traction motor can be very close to the underside of the bolster. Among other things, such an arrangement results in a more rigid motor mount. Furthermore, the truck is easily detached as a unit, as all that needs to be done is to disconnect hoses and remove the center bolt.

BTW, the effectiveness of the design is predicated on the truck/bearing/frame interface being a rigid assembly. That center bolt is torqued to 110 lb/ft and shims are used so there is zero clearance between the anti-roll bearings and the wear pads on the frame. I used the same design in the riding car (illustrated below, it's a better photo than any I have of the loco).

truck_frame_interface.jpg
Truck Attachment on Control Car
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rkcarguy
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Re: 12" working railroad

Post by rkcarguy » Wed Jun 03, 2020 6:59 pm

My hardware order came, so its time to resume assembly. I'm hoping to have the other truck assembled within the next couple days and get the riding car rolling.

rkcarguy
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Re: 12" working railroad

Post by rkcarguy » Tue Jun 09, 2020 12:10 pm

The riding car finally rolls on it's own! I thought I'd blown the coupler height and was about 3/8" high, but when I assembled the 2nd truck, mounted it, and lowered the frame onto the tracks it was right at the proper height. Thank you AutoCAD!
This frame is getting heavy, so I've been using a scissor jack to lift each end when messing with the trucks. I was concerned with the clearance between my brake drum and the brake line/safety chain bracket when on curves, so I slid the frame over to the curved portion of my turnout (40' radius), and it clears just fine. Looks like I'd probably be in the 20'-25' radius range before things start touching.

rkcarguy
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Re: 12" working railroad

Post by rkcarguy » Sun Jun 21, 2020 3:16 am

New picture
7CEF734A-4747-4AA0-9B88-56A76FC0E096.jpeg

tomc
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Re: 12" working railroad

Post by tomc » Sun Jun 21, 2020 8:29 am

here is a pic right side up. You need to figure out how to hold the camera so pics will end up properly on the internet. U must have an I-phone as I had to learn mine.

Tom C.
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