A two-teeth difference cam disk profile swing movable driver is introduced

whose transmission principle

structure and characteristics are investigated. The theory and task tooth profile equations of central internal gear are deduced by a new way. After taking off the process to solve the profile curvature

the curvature distribution along the gear profile curve is analyzed. Based on these

the tooth profile is imitated by the MATLAB program

and the effects on the profile’s geometry with the involved parameters are analyzed. All the results can basically assist to the stepped designs and analysis on the internal gear.