How it all began....How it all began....Jim Brown started by placing his hand on a wooden board laid across the rollers of the machine. The shearing head of the machine started to move towards him, the rollers slowly climbing over his hand, followed by the sharp teeth of the shearing comb following the measured profile faithfully just millimetres above his skin. It was an impressive demonstration.
The board was removed and a sheep placed on the belt,
with its legs stretched out at each end and secured in two pairs of clamps.
The rollers turned, and with them the sheep. The leg clamps were mounted
on rotating shafts so they could keep pace with the animal. Once on its
side, a stiff rubber cover was laid over the rear legs to provide a 'landing
strip' for the rollers to run down to the sheep skin. The machine was started
and a dozen faces watched in suspense as the rollers, followed by the cutter
climbed up onto the side of the
sheep, hidden from view by the vibrating wool.
The sheep twitched slightly and the tension mounted. Finally, with the cutter nearing the end of its run, it lifted clear of the sheep and returned automatically to begin another blow where it stopped. The rollers hummed for a moment and the sheep was turned slightly. We all moved in to see what had happened. Anxious arms pulled away the shorn wool to reveal an evenly shorn strip with a slight jiggle where the sheep had moved. We moved back for another blow, and then another after which a reasonably clear patch of sheep had become visible. However, the next time the rollers moved to turn the sheep, it flopped over too far, and the next blow was way out of line with the rest leaving a rather scruffy result. Some minor adjustments were made, and this wool too was shorn off.
We were then informed that this sheep was called a crossbred and was relatively easy for the machine to shear. So the next sheep put on was a Merino, with finer, denser wool and more wrinkles. The result was not nearly so impressive - the rollers seemed to run out over the top of the wool and the cutter seemed to be too close to the skin one moment and too far away the next. It strained to push through the wool, overloaded one of its motors, and stopped with the cutter pointing straight into the side of the sheep. Jim restarted the machine and tried again, but the shearing was ragged. A few more blows were tried, but the machine was obviously having great difficulty dealing with the sheep.
I was most impressed in all kinds of ways. First and foremost, I could see that the idea could be made to work, though not with this machine of course. I was most impressed with the care which had gone into the making of the equipment. Finally, I was impressed that the complex program of instructions for the machine had been set up with 'hard-wired' logic circuits.
I had become quite used to the idea of using a computer as the controller so it was a surprise for me that PATS had chosen this approach. It certainly was a major limitation to their design because changes which might have seemed sensible involved major reconstruction of the hardware, taking considerable time and effort.
The principal problem with the machine was the profile measurement method - the wheels simply did not penetrate the dense fleece wool of Merino sheep. A further problem which occurred was the tendency of the wheels to sink further into soft parts of the sheep than the hard boney parts. Therefore, the cutter height had to be offset so the comb did not sink into the soft parts. However, the offset needed for this was too great for the boney parts over the rib cage - here the cutter was too far away from the skin. The difference in softness was much more pronounced in Merino sheep than the English breeds tested in Cambridge.
Jim also had recognized that the method of supporting the sheep was too simple, and a more elaborate method would be needed to shear more than just the back and sides of the sheep.
Sadly, neither I nor my fellow technical reviewers could recommend further development of the machine. Without conversion to computer control, a new profile measurement method, sensing of the skin at the cutter and better animal support, it would be very difficult to make significant improvements. Our reports were to be strictly confidential, but the disappointment was written across Norman's face.
In May, the Corporation announced that there would be no further funding for the SDSRC project. Norman immediately announced that the SDSRC would fund further development of the machine. The Lewises had to dig deep into their own pockets to pay for the machine to be shipped to the newly opened Melbourne office of PATS where work was resumed until the end of 1977. Jim Brown returned to England, so the work in Melbourne had to be undertaken by new engineers unfamiliar with sheep. By the end of the year with another $60,000 spent, Norman was frustrated and disappointed and resolved to conclude his personal interest in shearing robots.
Norman and Marjorie returned to their Kojonup farm and after a while focussed once again on Marjorie's interests - fertility. On their own, they continued to persevere and were finally rewarded for their efforts. They continued to refine their flock, carefully culling the unwanted progeny in each generation. But still, the main stumbling block was the relatively high mortality of the lambs, compared to other breeds of sheep. In recent years, they have found that the trace element selenium in minute quantities has had a startling impact, and their lambing rate has climbed to 98% in a flock of 8000 ewes. A truly remarkable result and a clear 30% over the 'acceptable' or 'reasonable' figure. They travelled widely and commanded respect in the highest quarters of the wool industry. They continued to lobby in support of the automated shearing research project and visited our laboratory when they felt able to. There is no doubt in my mind that their unique combination of determination, connections, influence, hard work and their obstinate refusal to be 'quiet' was the initial driving force which provided the momentum for robot shearing research to get under way. We have good reason to be grateful.
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September 1997