Shake It Out

The next step in the thresher’s development was the way in which chaff and kernels of grain were separated from the straw. By the mid 1860s, many Canadian manufacturers, such as P.T. Legaré (710572), were manufacturing variations on the “Vibrator Separator”, which had been patented by the Nichols and Shepard Company of Battle Creek, Michigan. In this device, the conveyor was replaced with a series of straw walkers or racks, connected to a concentric that caused them to shake back and forth longitudinally. Rows of wooden or metal fingers caught the threshed stalks as they left the cylinder, and each progressive sweep shook grain kernels out of the mass, transporting the straw to the rear of the machine. Manufacturers insisted that the shaking motion guaranteed the removal of more kernels than was possible with the conveyor method. The partially-cleaned grain fell to the bottom of the machine, where a re-feed conveyor brought it back to the front of the straw walkers for a second cleaning. The kernels fell through sieves mounted just above the pan or bottom of the machine, where a chute on the side could be opened to feed the grain into a bushel measure, then into grain sacks.

Vibrator Separator manufactured by P.T. Legaré (710572)

This system of straw walkers mounted above a perforated sieve quickly became the standard for mechanical winnowing technology. Once the straw had been carried past the walkers, it dropped onto the ground at the rear of the machine, where labourers pitched it into a pile or straw stack. Not only did threshing machines equipped with straw walkers operate differently, but their appearance had changed as well: the small squat box on skids had been replaced by a long rectangular box on wheels.