Crushes and sorts coal lumps by size for different use.
For example, coal for a kitchen stove uses a small size.
This Coal Breaker produced 5 different sizes if I recall
correctly.
Many homes used coal for heating and cooking long ago.
Coal straight from a mine of the era might contain large
lumps of 12 to 24" or larger. Now many coal mines use
mechanical digging machines which destroys a lot of
the huge lumps.
Locally here in Delta County CO they advertise 'Stoker
Coal' which is graded for size that will run thru the
stoker auger of automatic home stoves.