The Monitor Self Oiling windmill was the successor to the open-geared Monitor and was imported into and sold widely in both Western and South Australia.
This model goes by the wonderful nickname of hambone and the source of this name is obvious when one looks at the overall shape and the ribbing on the gearbox.
It is officially the Monitor Self Oiling windmill and was made in three sizes, the 8ft C model in 1923, followed by the 10ft D and 6 1/2 ft B.
When they appeared in Australia they met with immediate success and were awarded First Prize and a Silver Medal at the 1927 Adelaide Royal Agricultural Show.
The Self Oiling windmill is of a unique design in that the main casting envelops the whole of the workings and to access the internal parts of the head, a cover plate has to be removed from the rear of the casting.
It is similar to the Monitor Steel in that it only uses one set of gears. Unusually, the pinion gear was actually screwed onto the hub shaft with a left hand thread. The main gear operated a round bar single pitman arm which connected to a crosshead casting running up and down a large diameter vertical guide bar. From this crosshead the pump rod ran down through the mast pipe.
The Morawa Museum has a complete 8ft Monitor Self Oiling Model C windmill on display outside in the Museum yard.