Center Plate

This is the bearing plate between the car body and the Bogey, it is two plates, a male plate on the car body and the female ether on or part of the  bogey bolster. This allows the bogey to turn with the track and transfer the forces to or from the powered wheels.

Making it is just a cylinder the diameter of the bolster and should go from the bogey bolster up past the body bolster so you can have a "fudge factor".

This is the first non-animated part I usually make. Remember all parts that are not animated must be "linked" to the b.r.base or b.r.main.    

Axles

Axles are of two types, powered and un-powered. Below is the standard U.S. axle, the "D" is the most used.

To make you can use just 24 segments as you can not see axles that good. The only thing you need is "K" and "I" and "A+B" for the baring.

Powered axles are not tapered and for most Diesels you can not see the axle at all due to the motors and gearbox.

How I make Wheels for Trainz

I like to re-use the same wheel so I made a new wheel in 2009 and have been modifying a copy ever sens. I use the "spin" method with 32 segments, if you use less the wheel will not look round. The "spin" method is just making the cross section of the wheel and spin is 32 times. Below is what I used whit Y being around 4", there is some of the image not showing where the center line is in the axle hole, I photoshoped it into a full wheel so that D was 33", I do not remember where I got this other than a website selling railroad wheel in 2009.

 I detach the tread and flange then do the texturing as they have a shiny look. Then test in game, I do this a lot. Next I make a clone and flip it for the other wheel, note I do not make the two wheels into one object.
If you need an axle add it now, this can be 24 segments and will be covered later.
Next is to do the animation and test that it fits the track and that the animation is working right, this can be a nightmare.

After you have one set of two wheels working you can dup to make a 4 or 6 wheel bogey, just keep the names right.

Wheels

General

Wheels are of 3 types, plate, spoke, and plate with holes.

U.S. wheel part names for a plate wheel:

Hub - the center part of the wheel where the axle hole is.

Plate - the part between the Hub and the Rim, where the spokes are on a spoke wheel.

Rim - the part that has the wheel Tread and Flange.

Tread - the part that is on the rail head.

Flange - the part that keeps the wheel from going off the track.

U.S. wheel part names for spoke and plate with holes wheel:

Same as for plate wheels but can have counterweights.

Wheels are made of ether iron or steel and are made to standards witch have changed over the years but for use in Trainz most of the changes are so small that you can not see them. An example the wheel Tread use to have a tapper of 1 in 6 and now 1 in 20, know one can see that!

If you make one good plate type wheel you can them modify it into the other two kinds witch is what I do and I do not have to do the animation part over unless it has side rods.

I use textures to show ether iron or steel wheels, iron wheels have ribs on the inside Plate. There was also a time when paper wheels where in use for passenger cars to give a better ride. The paper was compressed and had metal Rims and a flat metal plate on each side and a ring of bolts holding it on, witch is how you can spot them. I have not made this type yet but a texture should work.