Abstract: The bearing 607 in the pusher of knife feed mechanism in PROTOS 70 was damaged frequently because of heavy impact,therefore the feed mechanism was improved as following:1) bearing 607 was replaced by a double-row angular contact bearing 5200,which could sustain axial force;2) a spacing bolt was added on the pusher jacket to keep the pusher contacting with connecting shaft all the time,and reduced the impact during knife feeding.The working life of knife feed mechanism prolonged from 6 months to 24 months,and its maintenance frequency decreased accordingly.