Bearings and Journal Boxes

Bearings

Railroads use two types of bearings for bogeys, plain or solid bearings and roller bearings. 

Plain bearings are made of babbitt and where in use for about 150 years. The bearing had to have a lubricant, mostly oil, witch had to be applied by "waste or lube-pad", if it did not get it you got a "hot box" witch can cause a derailment. A good working lube-pad did not show up until the 1950's witch was to late, laws banning them showed up.

     

Roller bearings have 30% less friction witch is why the first railroad car with them was made in 1830 on the B&O, they did not work out. More were tried in the 1920's but cost to make were to high. By 1957 only 10% of new cars came with roller bearings, by 1960 it was 64% and now is 100%. Roller bearings could be retro fitted to older bogeys by replacing the journal box or by modifying it.

You will never have to make bearings as they are inside the journal box but the journal boxes due look defendant, even the ones modified for roller bearings have a look.

Journal Boxes   

Plain bearing journal boxes have to have room for an oil supply, wast, a bearing, and the axle end all in a dust free box that can be opened a lot. So a journal box has a dust shield where the axle comes in and a spring loaded door cover.

I like to make this type as 3 parts, the round bottom part, the top part, and the door lid. The door lid can be dropped in LOD. the bottom part I make starting with a sphere and cutting off the top and back.

Roller bearing journal boxes can be "open" or "closed", the older ones are of the "closed" kind and come in a variety of shapes.

The "open" kind is what you see today and the center is part of the axle and should be animated.

  

Springs

Bogeys use semi-elliptic, elliptic, coil, Volute, and snubber spring.

Semi-elliptic springs are made of flat bar steel bent into ether a very flat "V" or "C" and then stacked up smaller on the bottom and a strap holding them in the center. This gives a spring that only "springs" one way but can be made very strong. Mostly used on Locomotives.

Elliptic springs are two semi-elliptic spring joined at the ends one on top of the other, this gives "spring" both ways and a much better ride. Used on passenger cars, locomotives, caboose, and some fright.

  

Making them is simple, make one bar and duplicate it making each one longer. Do make a simpler one as a triangle for LOD.

Coil springs are the most used but give a so so ride. Making them can take some time to get one that looks good but after you have one good one you can copy and re-size it for all other coil springs, I have only had to make one in 6 years.

Volute springs (roll up a piece of paper and pull the center out and you have one) is made of flat steel rolled up so that the sides rube on each other and the center is higher than the outside, this gives a damping effect and a better ride. Can be made by just a cylinder.

Snubber springs are not really a spring but a damper made of robber.

What is being damped is a harmonic oscillation that well develop in coil springs.

Fright car bogeys can have a lot of configuration, you can have one coil spring inside a another, you can replace a coil with an elliptic or Volute spring or a snubber.

      

Freight car Bolsters

The Bolster on a 4 wheel freight car holds the side frames together. It also supports the top of the springs, the center plate, and two side bearings. First made of wood then fabricated of steel then cast steel witch is by fare the most used from 1900 to now.

Most of the Bolster can not be seen very well in Trainz due to the cameras so you only need to get the ends right, the rest just needs the general shape, this saves a lot as the cast steel ones have holes all over.

The side bearings are at 2'1" from the center of the bolster and are rollers or sliders that run on a steel plate on the bottom of the car body. They do not touch unless the car is moving on a curve. I have made them by just a box with slanting sides, you can not see them most of the time.

There is also a spring plate used on the bottom of the Bolster but can not be seen, it holds the springs in place.

 

Making a Freight Car Bogey

Note: I use Blender so some names maybe defendant for other 3D programs.

I start out with a 32 segment cylinder the size of the Journal box, extrude the top half up to the top of the frame, delete 3 sets of vertices, and move some as shown in Fig1.  

Fig1

Next I extrude the 4 vertices on the right side of Fig1 to that in Fig2, I have also added a set of vertices to the bottom so that all the hole is covered. This is then separated and a face is added so that this is now a solid object. This is going to have a Boolean hole cut into it and the Boolean tool works on volume so the simpler the object the better. 

Fig2

Next up is the hole witch is made also from a 32 segment cylinder. In this case 3 of the 4 curves are the same size so I move them into place and make the object wider than the one just made. It looks like Fig3.

Fig3

The Boolean should look like Fig.4

Fig4

After the hole is cut out I add some more vertices to the bottom and extrude the 4 vertices on the right side and do the same as above but with a square hole, Fig5.

Fig5

I then select the black part of Fig5 and duplicate it, mirror it, move it , and do a flip normals on it. Last is to join all the parts into one, remove extra faces, and smooth the round parts(not done for this yet) giving you Fig6.

Fig6

  

Bogey Frame - Freight

The first railroad cars were all 4 wheel with pedestals, this worked and was used for coal cars and on caboose cars and were in use up to 1900 or so. The 4 wheel bogey or 8 wheel car soon appeared in the US but know one knows when, who made it, what it looked like, or what railroad it was used on. What came common was a 4 wheel bogey with 4 pedestals and a hard wood frame but by around 1850 the wood needed was getting hard to find and the wood frames would get "out of square".

Wood bogeys are not hard to make in Trainz, only the pedestals, springs, and journal boxes are.

The next improvement was the Arch-bar bogey, this was a big change in how the springs worked to keep the wheels on the rail. The springs were moved to the center of the bogey with the tops on the bolster and the bottom on the frame, this allowed the axle ends to move up and down but the journal boxes were now fixed to the frame. The frame was made from flat iron or steel bars, normally 3 bars per side held in by 6 bolts. This type is still in use today in some places. In the US some lasted up to the 1960's.

The big problem was the holes in the bars made a week point witch is why they were banded.

Arch-bar bogeys are also ease to make for Trainz.

In 1888 the first press-steel bogey was made by Fox and others fouled up to 1903 when Bettendorf came out, a cast steel side fram witch is still in use today. Known as a "Self-Aligning Spring-Plankless Double-Truss Truck". There are a lot of variation on this, some with cast in journal boxes some without. You could get them in 40, 50, and 70 ton sizes.

    

Above is a 70 ton

The Pedestal

From the 1941 Car Builder's Cyclopedia:

"Pedestal - In old designs of built-up trucks(bogeys)*, a casting of somewhat the form of an inverted letter 'U', bolted to the wheel piece of a truck(bogeys)* frame to hold the journal box in place horizontally, but permitting a vertical movement. The two projections of a pedestal are called pedestal legs, and the space between them a jaw, which is closed at the bottom by a pedestal tie bar. In Great Britain pedestals are called axle guards on cars and horn plates on locomotives. In modern trucks(bogeys)* the pedestals are cast integral with the truck(bogeys)* frame."

* added by me

In the US you find these on 4 wheel cars and wood passenger cars. Below is the old and a photo of a cast modern one.