The calculation of the tangential values of module m, pressure angle [alpha], helical angle [beta] on the
base circle, pinion [r.sub.bp] and wheel [r.sub.bw] base radii are evaluated in equations (4), (5), (6), (7) and (8) respectively:
In (Flores, 2013) a computational methodology for the optimized design of disccam mechanisms with eccentric translating roller followers is presented; the objective function takes into account: the cam
base circle radius, the roller radius, and the follower offset.
The geometry of an involute gear results in its having a pitch circle and a
base circle. The meshing force can be described as shown in Fig.
(2)
Base circle: The circle from which an involute tooth curve is generated or developed.
The
base circle radii for pinion and gear can be obtained as:
The profile called "direct profile" belongs to the positive side of an involute with the
base circle diameter dbd--the direct profile
base circle diameter.
The most important geometrical parameter of asymmetric gears is the coefficient of asymmetry "k" defined as the ratio between the
base circle diameter of the inactive flank and the
base circle diameter of the active flank (Litvin et al., 2000).
In the optimisation phase of the study for this project, GIW discovered that increasing the geometry of the
base circle by 10% would reduce wear by 30%, while adding only 5% to capital costs.
The contour required for the scroll compressors, known as an "involute", is defined with reference to a
base circle. "You could look at it as the curve described by a point on a thread kept taut as it is unwound from a central core," says Mr Fletcher.
Instead of involute or other curved tooth forms, double-enveloping gears have straight-sided form is tangent to a common
base circle. It allows more tooth area contact.