Güterwagen Omk (part 7) Leaf springs

For the OMK wagon, used as driving truck, hefty leaf springs are needed to take the off-scale load of a full size driver.  So I've ordered 13 x 2 mm spring steel (quite expensive €56 for 6 meter) to make working leaf springs.

I've ordered also a book about "Offene Güterwagen" from MIBA Verlag (Band 3). This is a book that describes almost all open goods wagons that ran on the German railways.  Lots of details, explanations in text about the construction, history and a reference to models (H0 scale).

At a modelshop I've even picked up a N scale version of such a wagon. 

The brake cabin got a second coat of paint. 

The spring steel cut to correct length. I had to adjust the length of the individual blades, so I was able to make 8 sets out of the 6 meter of material. 

I'm not sure if the steel already has got any heat treatment; it is however quite tough and hard to drill. The burs had to be removed with a small grinding tool. 

I tried to bend the lugs on the outer end of the top leaf, but even after softening the material (heating it up to red heat with a propane torch, and let it cool down slowly), it was still too brittle to bend. For bending it red hot, I didn't have enough hands to hold the torch to heat it, and bend (hammer) it around a small rod at the same time.  

So I've opted for silver soldering lugs, made on the lathe.

Before cutting all the springs, the first one was assembled and tested on the scale. It takes about 37 kilograms to get a compression of about 6 mm. (just not fully horizontal)

 Than the height was checked. With this curvature in the blades, the buffers are a bit higher than on the locomotive (136mm above rail head) 

Shackles were used of a bicycle chain. These are almost the correct size (I had different sizes of chain to choose from, even from a motorcycle, only the holes had to be opened out to 4 mm. 

With pins these shackles will connect the springs to the spring holders.  

Taking the wagon to a model engineering exhibition with of Stoomgroep Zuid in Wijchen. The total weight of the wagon is already a bit too much to lift it alone by hand. 

The spring holders (if that is the correct English name for it) are the connectors between the spring and the frame. With the shackles in between the spring blade and spring holder, there is still a bit of flexibility for the spring to expand during compression and move.  

The spring holders on the real wagons are cast items.

I've made them from mild steel strip and a turned bush.

With this simple jig, the spring holders are silver soldered. 

I started with making two spring holders, to test their dimensions and locate their position on the frame. The rest was made in a batch. A total of 16 all together: also a set for the beer wagon. 

With measuring, testing the concept and making the jig, almost the same amount of time is used for the first two, than for the remaining 14 pieces.

Drilling the frames for taking up the spring holders. With M3 screws these are fixed to the frame.

Pins are used for assembly.  These 4 mm pins are cross drilled, for taking up split pins. This drill jig is to make sure that the hole is going through the middle. A stop bolt is used to set the correct distance from the end. 

In total 32 of this pins were made.

Springs connected to the frame. 

 A photo I've taken when the wagon was standing on a short piece of track, me sitting on the wagon. The compression is about 4 mm  and the wagon is easy pushed around. 

So I believe the calculation matched up and I can now finish the leaf springs. (a buckle in the middle is needed) 

Güterwagen Omk (part 6) Wheels, axles and bearing blocks

The winter season is here again; the time of year that is ideal for model engineering. So I've picked up where I left almost a year ago.

The first thing I've tackled are the horns and bearing blocks. For practical reasons I've decided to use ball bearings, but still make a reference to the appearance of the original plain bearings. So not exactly to scale, but reliable in use. I had some 6202 2RS bearings, and adapted the blocks to suit them.

There is about 2 mm sideways play between the horn cheeks and horn block . This play is as original on real wagons and makes it able to shift the axles and adjust themselves to a curve on the railway.

This self steering axles (Vereins Lenkachse in German) were used to reduce the rolling resistance and minimize wear and tear on the wheel flanges and rail heads. 

The axles are 20 mm in diameter and were turned between the centers

The wheels are glued to the axle with Loctite 601.

The inner ring of the bearing is locked on the axle, with a custom made end cap. 

The bearing house provides a sliding fit of the outer ring of the bearing. 

Not much detail here, but a functional housing that will stand up the load and sometimes rough handling on the miniature railway.

With a radius mill the sliding block is formed.

To give the front a bit of appearance, a fixing plate for the front cover is CNC milled to shape.

There is just enough space for M2 screws to fix the plate to the bearing housing 

My son was able to 3D print in stainless steel the front cap during his internship with KMWE in 2015.  

You see that even making wagons is taking up more time than anticipated. 😀 

With a wink to the original caps, the text makes a link to our own workshop. 

We used the letters of KMWE to make our own name  "Klein Metallwarenfabrik Eindhoven" (Small metal parts factory Eindhoven)

Lying upside down the axles are test fitted on the frame.

From Gauge 1  (scale 1:32    Märklin 5838)

 to Solidworks

and 7¼ inch gauge (scale 1:8)