CSIRO take up the lead....

David Henshaw also had a dream......

CSIRO: Commonwealth Scientific and Indutrial Research Organization.

The Corporation did not put all their eggs in one basket. CSIRO Physicist, David Henshaw had become convinced by his experiences on the Wool Corporation's working group that automatic shearing was possible, and in his laboratory in Geelong he had already started working on a machine to shear a single blow along the back of a sheep. John Clegg, also on the working group, had suggested that David provide the machine with a means of sensing the skin of the sheep at the points of the comb. He had discovered that a small electrical current could pass between the comb and the sheep skin - as the comb was pressed harder onto the skin, the electrical resistance to the current was reduced. He and David coined the term 'resistance sensing.

David had realized that it would not be necessary to measure the profile of a sheep if a machine could sense the skin. Feedback control could be used to adjust the position of the shearing handpiece automatically. This would have the advantage of responding automatically to animal movements such as breathing or struggling.

The Corporation provided CSIRO with funds and the race was on to build the world's first sheep shearing machine. Within weeks, by mid 1975, David had the first machine ready. The front of the handpiece could be driven up and down by one electric motor and the back end by another. The motors were driven by the outputs of powerful amplifiers operating on the electric current measurements.

The sheep was strapped onto a wooden beam mounted on a trolley which could be moved under an archway. The handpiece hung from the middle of the arch on a long lever which was moved up and down by the motors. When the sheep emerged through the archway, a neat strip of wool had been shorn along its backbone. David was elated and pressed on with a more complex machine which would be able to shear the side of a sheep.

CSIRO have their turn too.....

....back to chapter outline

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