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In this work, new approaches for the dimensional synthesis of both tooth and operating basic surfaces for hyperbolic gear transmissions are presented. Both traditional worm-gearing hyperbolic transmissions (point contact) and non-traditional ones (line contact) are considered regarding constraints as the manufacturing method, the standardized tool modules and the limit normal of contact. For point contact, the location of the pitch point is done by chosen the parameters of the operating basic surfaces (the cone angle of the worm) and of the teeth basic surfaces (axial module and helix angle of the worm). For line contact, the given parameters of the operating basic surfaces are the cone angle and the worm radius at “zero plane”, and the axial module of the teeth basic surfaces. A comparative study of optimal synthesis, considering different solutions of traditional (point contact) hyperbolic transmissions and non-traditional (line contact) ones, is also included. The objective functions were the sliding velocity and the efficiency, and constrictions above were considered.Copyright © 2003 by ASME

This paper represents an enhanced approach for application of longitudinal plunging in the manufacturing process of spur gear drives in order to localize the bearing contact. The proposed approach is based on application of a grinding disk performing a planar curvilinear trajectory. The main innovation is the tilt of the plane containing the curvilinear trajectory performed by the center of the grinding disk. The proposed manufacturing process allows the following improvements to be obtained: (i) uniform length of the major axes of the instantaneous contact ellipses all over the path of contact, (ii) reduced sensitivity of the shift of the path of contact to errors of alignment, and (iii) reduced level of contact and bending stresses. Numerical examples of design are represented.Copyright © 2003 by ASME

The minimum number of teeth to avoid undercut on involute spur and helical gears depends on the pressure angle, among some other geometrical parameters. Higher number of teeth is required if the pressure angle becomes smaller. However, the contact ratio may be increased by reducing the pressure angle, which means the load is distributed along a longer line of contact. In many cases, even if undercut arises and teeth are weakened, both effects may result in higher load capacity for the gears. This paper presents a study on the influence of the pressure angle on the contact ratio, and through it on the length of contact and the load capacity, including a discussion on the condition to improve the load capacity by reducing the pressure angle beyond the undercut limit.Copyright © 2003 by ASME