There are many risks in using grass cutter because of the pebble in grass and high speed rpm when the cutter hits the hard objects in grass. In this study, the existing patents are surveyed and classified for the new mechanism about the bottom safety cover. The new mechanism was modelled and the planetary gear are designed. The power source (engine or motor) will rotate the sun gear and the carrier of planetary gear is fixed into handle frame. The ring gear will drive the final cutter. The carrier fixed the bottom safety cover through the planetary gear hole at the handle bar. In this paper, we develop a new mechanism and analyze the idea for safe grass cutter and investigate the possibility of having patent through patent search.

Abstract
 1. 서론
 2. 기존제품 및 특허분석
 3. 안전판 예초기의 설계
  3.1 메커니즘 설계
  3.2 기어설계 설계
  3.3 저널베어링 설계
  3.4 예초기 구조 설계 및 제작
 4. 결론
 참고문헌

• 염광욱(중앙대학교 대학원 기계공학부) | K. W. YOUM
• 신재원(중앙대학교 대학원 기계공학부) | J. W. SHIN
• 전한수(한국 산업기술 평가관리원) | H. S. JEON
• 오세훈(중앙대학교 기계공학부) | S. H. OH