I have had this plan for a wide-ranging coking operation. One step is that I need to break/crush the coal from the mine prior to running it through a process that will separate the coal from the trash such as slate. This requires a device of some sort to break and crush the coal/slate mass. I’m going to follow the process I went through to design a coal breaker for my On30 coking operation. I think along the way there should be plenty of opportunity for someone to find something that would ‘fit the bill’ for their own operation – whatever it is.

The Coking Bible

Coke: A treatise on the manufacture of coke and other prepared fuels and the saving of by-products, with special references to the methods and ovens best adapted to the production of good coke from the various American coals (Google eBook)

This is the one of my main sources for a lot of my information on coking. In particular, for this thread on a coal breaker.

The ‘why’ of a breaker

“… It has been discovered that breaking the coal that comes from the mine in large lumps, especially when the percentage of its volatile matter is small, adds to the value of the coke … it has been found that a mixture of lumps and fine or small coal fuses unevenly in the process of coking .. that all coals will be benefited for making a uniform quality of coke ..” – in other words, it’s advisable to crush coal for coking. From there the book goes into talking about how specifically the coal is crushed depends on the physical properties of the coal being processed. From that .. I then just went with the breaker that I liked best since my coal is .. well .. imaginary .. I could easily design a breaker then ‘imagine’ whatever properties necessary for that said breaker/crusher.


The photos below show a variety of breakers, distintegrators and crushers from Link-Belt Machinery Company, Chicago, Illinois.

  • On the left is labeled a ‘Coal Breaker’. The size and spacing of the teeth were made to suit the size the broken coal was needed. In general the smaller the diameter of the roll the greater the percentage of fine. Conversely, if a certain size was required then the roll would be a larger diameter. Following that was a chart showing the size of the rolls with weight, capacity in tons per hour and horse power required. That will be important later but let’s continue for now with the other machines.
  • In the center we have what is described as a ‘Disintegrator’ .. for crushing to a very fine state. A note that it was made in two sizes .. a 36-inch diameter, 20-inch face and a 48’inch diameter, 24-inch face.
  • Finally, on the right we have a Coal Crusher with one smooth and one corrugated roll.


With a handle on the general design of a breaker, I then needed to see what capacity I needed for my Coke Oven Bank.
In ‘Real Life’ coke oven banks were very large. Banks of 50 or 100 ovens .. with multiple banks were common. Operations having 500 ovens evidently were used to supply coke to steel mills. My little operation of 16 ovens is therefore .. ‘quaint’. My explanation is that they supply coke for local foundries.

Each oven took a charge of between 4-6 tons of coal. My ovens are selectively compressed in width .. even with the width 3/4 the length the 16 ovens still take up 41-in modeled in O scale. Since I used selective compression I made a WAG that each charge would be 4 tons for my ovens – but let’s bump that up to an intermediate 5-tons just for grins. A coking operation runs on a 48-hour cycle. An oven is charged at 12-noon on Monday and the coke is pulled at 12-noon on Wednesday (more or less). What this means is that half the ovens are charged each day. 5-tons x 8 ovens = 40 tons a day required. Let’s further say that to be on the safe side we double that to 80-tons per day.

The chart on the left is a modification of the one from Coke: – showing roll size with capacity. From that we can see very quickly that our 80-tons per day requirement could be satisfied very easily by the smallest rolls shows – the 15-in dia x 20-in long roll which had a capacity of approximately 10-tons per hour. That means even the smallest roll could meet our 80-ton per day requirement in just 8 hours.

The last one – the Mimesis 30×40 has the data generated via a bit of reasonable calculations. I created a 3D model of this version simply to get a large enough model – even in O scale.

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