The number of labourers employed has a pronounced influence on the work rate of the machines, particularly that of the smaller units with unmechanised loading.    From Wordnik.com.  [Chapter 6] Reference

His widdow & 2 boys went on to run a 50 head dairy behind Caboolture completely unmechanised & un electrified until the mid 60’s.    From Wordnik.com.  [Cheeseburger Gothic » Anzac Day] Reference