A maintenance man was working on a first floor roof on a routine service on a flour silo at the rear of Earl's Bakery in Sidley on Monday lunch-time when his arm was caught in the mechanism.
Stuart Cowley-Wenham said that luckily his business partner Simon Knight was with the maintenance man when the accident happened and was able to raise the alarm.
The device employs an Archimedes screw to lift flour into the silo.
The machinery is serviced on a regular basis by the maintenance man.
Mr Cowley-Wenham said cogs in the mechanism caught the sleeve of the man's overall, trapping the flesh of his arm.
He paid tribute to the emergency services.
"They were fantastic. I rang the ambulance and they were here in two minutes. The fire brigade put up ladders to help the ambulance crew lift him down.
"He had to go to hospital for stitches. It's torn the flesh of his arm but fortunately it is not more serious."