Prof. em. Dr. Jože Hlebanja, univ. dipl. inž., University of Ljubljana, Faculty of Mechanical Engineering, Slovenia
Dr. Gorazd Hlebanja, univ. dipl. inž., University of Novo mesto, Faculty of Mechanical Engineering, Slovenia
Dr. Mark Umberger, univ. dipl. inž., Entia, d. o. o., Ljubljana, Slovenia

Abstract:
Gears featuring the curved path of contact were implemented in heavy industry where it was proven that such gears can successfully replace involute gears. Purely graphical method of design was later replaced by an analytical definition which enabled calculation of not only gear geometry but other relevant aspects as well (e.g. sliding velocity, curvature radii, etc). So, the most important definition is that of the rack profile which can be regarded as a cutting tool profile. Thus, the tooth flank of the rack profile defines the unique path of contact. And according to the law of gearing gears (external and internal) of arbitrary number of teeth are derived from there. Furthermore, the paper describes helical gears and crossed (perpendicular) helical gears which can be used in multiplicators.

Keywords:
power transmission, involute gears, S-gears, helical gears, crossed helical gear pairs