The first wood chipper was invented in Germany in the late 19th century according to my research on them.
They were not used a lot commercially until the 1950's when the first chuck n duck high speed drum chippers hit the markets. The production efficiencies gained by being able to shred brush and relatively small diameter wood up to ten inches into small chips blown into the back of a truck was a game changer, and their use really took off commercially.
The sheer speed at which these drum chippers could grab and shred a branch was truly frightening and intimidating for the workers feeding them. If the operator didn't quickly move to the side and past the feed table after feeding a branch? The consequences were dire. Hence the nick name chuck n duck, or be whipped, slammed against the feed table, or be peppered by wood chips propelled backwards at the operator at extremely high speeds. Unwary operators of these high speed drum chippers lost fingers, hands, arms, teeth etc. but rarely their lives.
However in the late 80's when the first hydraulically fed disc and drum chippers hit the markets that were capable of shredding large diameter brush and logs up to 18 inches plus at a much slower feed rate? Shortly thereafter the first woodchipper operator fatalities were reported and documented when operators became entangled in the branches being fed and dragged into the hydraulic feed wheels and dismembered. The vast majority of these woodchipper fatalities occurred when the operator was feeding the chipper alone with no one about to activate the safety feed control bar which stops or reverses the feed wheel mechanism.
As these hydraulically fed woodchippers able to chip large diameter branches and logs became more numerous and widely used in this industry, operator fatalities on the job rose.
This led to OSHA releasing the following bulletin in an attempt to reduce the rising number of on the job woodchipper fatalities in the US.
https://www.osha.gov/dts/shib/shib041608.html
Note the number one recommendation. To always have two operators working in close proximity to the chipper, with one of them acting as the designated observer with their hand on the feed control bar in case the other operator gets into trouble.
The now dated OSHA woodchipper safety bulletin does not reflect the fact that over 55 woodchipper fatalities have occurred on the job.
IMO any hydraulically fed woodchipper over a ten inch capacity should never be fed by a solo operator, period.
I hope you bear these grisly realities of this dangerous industry in mind when purchasing a woodchipper John.
Work safe mate.
Jomoco