Bogie Truck Setup

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Steve Goodbody
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Bogie Truck Setup

Post by Steve Goodbody » Mon Jan 10, 2022 5:05 pm

Hi all,

I'm looking for advice on how best to mount some bogie trucks on passenger-carrying cars, specifically where to allow slack, and and how much slack to allow, to prevent derailments. These are MCC Bettendorf truck, but I doubt that that's particularly relevant. The marked-up picture below shows one of the trucks.
InkedBogie Truck - Markup Small.jpg
At present, side supports (A) and central boss (B) are all at the same height above the railhead and all bear against the car's flat mounting plate. The pivot pin is a good rotating fit in hole (C) but with no slack.

Perhaps unsurprisingly, on first trial the cars derailed regularly. I assume this is because I have left no slack in the pivot pin arrangement, so that weight applied unequally to one side of a bogie probably caused the opposite side of the other bogie to lift off the rail as the car's chassis rocked.

For focus, here are the questions that are probably most relevant:

1. Should the pivot pin be a slack fit in Hole C?

2. If so, is there a rule-of-thumb for how much clearance to provide? (for example, "allow the car frame be able to tilt by x degrees before the truck is lifted" or similar).

3. Does my diagnosis sound right or am I missing something more fundamental?

Many thanks in advance,
Steve

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ccvstmr
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Re: Bogie Truck Setup

Post by ccvstmr » Mon Jan 10, 2022 5:32 pm

Steve,

From my experience, I typically drill the kingpin hole 1/64" to 1/32" over the size of the king pin. Also, make the king pin long enough to I can insert an "R" clip on the under side of the truck...so the truck stays captive with the car when lifted for rerailing. Will usually put a large fender washer between the "R" clip and the underside of the truck bolster so it doesn't get caught inside the bolster.

Side sway...you need some. You don't want the car body sitting square on side sways at both trucks. Yes, that's asking for tracking problems. On my cars, I machine the center and side sways to the same elevation. Then insert a 1/32" Teflon fender washer on the king pin between the truck and the car body. This provides 1/32" side sway clearance for some sway motion. Have also used thin stainless steel fender washers to do the same. Some plastic sheet material will also work.

You didn't mention anything about the truck springs. Don't know what the weight rating is on your springs. Here again, don't want the spring tension to lock up the truck side frames do they can't pivot with the track deviations. There is a rule of thumb for this. With the truck sitting on a piece of track (ground or on the bench), you should be able to roll the truck over a 1/4-20 nut on the rail head. When that wheel is raised on the nut, all the other wheels should stay on the track. If not, the springs are likely too stiff. The problem you'll encounter is finding springs that allow some truck flexibility when the car is empty...and the springs won't "bottom out" when the car is loaded.

Does that help you any? Carl B.
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Bill Shields
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Re: Bogie Truck Setup

Post by Bill Shields » Mon Jan 10, 2022 9:03 pm

I tend to put more tilt in one end (A) than the other..this helps passengers feel more stable.

If you cannot get around the track without derailing then you need more tilt clearance.

It depends on the length of the car and how much ripple there is in the track.

A soft joint at the wrong location can cause a long car to detail.
Too many things going on to bother listing them.

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Greg_Lewis
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Re: Bogie Truck Setup

Post by Greg_Lewis » Mon Jan 10, 2022 10:22 pm

I do as Bill suggested with one truck having less clearance than the other. What's left of my memory says I've got one truck so the clearance is almost nothing, just a smidgen, and the other so there is about 1/16 to 3/32 total. My side bearings are from oil filled polyethylene which makes for a slippery surface with almost no maintenance. The car bolsters where the side bearings ride is also kept smooth. Finally, I put a round head screw in the truck sideframe where the truck bolster is pushed up against it by the springs. Thus when empty the bolster had a little pivot point there. This way the spring tension is hardly an issue and I've set up the springs to be right for when the car is loaded. When empty the truck sideframes will be able to tilt because of that screw. With this arrangement I've had almost zero derailments with my riding car trucks.
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Joe Tanski
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Re: Bogie Truck Setup

Post by Joe Tanski » Tue Jan 11, 2022 8:16 am

Take a look at Tom Bee web site good info on car and truck setup ,well worth the time excellent info
Joe

Pontiacguy1
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Re: Bogie Truck Setup

Post by Pontiacguy1 » Tue Jan 11, 2022 8:28 am

Finally, I put a round head screw in the truck sideframe where the truck bolster is pushed up against it by the springs. Thus when empty the bolster had a little pivot point there. This way the spring tension is hardly an issue
I like the heck out of that Idea. I will use that in the future.

Steve Goodbody
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Re: Bogie Truck Setup

Post by Steve Goodbody » Tue Jan 11, 2022 9:48 am

Carl, Bill, Greg - many thanks indeed for your guidance and suggestions, that's exactly what I was hoping for.

Joe - thanks for the suggestion about the Tom Bee website, which I was not aware of. As you say, there's very good information in there and, from what I can see, it matches closely with Carl, Bill and Greg's guidance.

Based on this information, I'm going to start by providing clearance for the pivot pin (king pin) in its hole and by using spacers to set the central boss higher than the side bosses. I'll try 1/32 at one end and 1/16" at the other as a starting point. I'm going to hold off from changing out springs and installing Greg's roundhead pivot idea until I see how things go with the first modifications. Those suggestions are now in the arsenal if the problems persist.

Thanks once again to you all - this is a great forum!
Steve

rkcarguy
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Re: Bogie Truck Setup

Post by rkcarguy » Tue Jan 11, 2022 12:54 pm

If you want the ultimate in flexibility, press a spherical bearing into "C".
Then drill a horizontal hole through the centers of "A" and install a bolt and a pair of ball bearings (or bushings) on each one.
The idea here is that the trucks can pivot up and down independent of the springs and rotate freely, but don't allow the car to tip to the side.
If you do this, you'll need to bevel the sides of "A" on each side of the bearings so the truck can pivot up/down some without the original side supports digging into the underside of the frame.

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