机械原理,是研究机械中机构的结构和运动,以及机器的结构、受力、质量和运动的学科。人们一般把机构和机器合称为机械。机构是由两个以上的构件通过活动联接以实现规定运动的组合体。机器是由一个或一个以上的机构组成,用来作有用的功或完成机械能与其他形式的能量之间的转换。这一学科的主要组成部分为机构学和机械动力学。Machinery Principle is a subjuct to study the structure and movement for mechanism, and the structure ,forcing, quality and movement for machine. Generally, Machinery includes mechanism and machines. Mechanism is a combination which is composed of more than two parts, which can meet defined movement throught the connection, Machine is composed by one or more mechanismes, which aims to output power or achieve the power exchange from mechanism to others. The majors are the mechanism and machinery power.