NZR B306 at Reefton with a works train on the West Coast, 1950s

The B class was a 4-8-0 type of which 10 were built between 1899 and 1903. It looks like the engine crew are engaged in cleaning out the tubes, which involves this process:

* The crew opens the firebox door to access the boiler tubes.
* The fireman turns on the draft blower to create strong suction through the boiler.
* Sand, compressed air, or specialized lances are introduced into the firebox.
* The draft pulls the cleaner violently through the tubes, knocking off hard carbon.
* The loosened debris is safely blown out of the smokestack.

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