The following are additions to those terms used for spur gears.
A = addendum B = dedendum C = cone distance D = pitch diameter Da = outside diameter Dr = root diameter E = bottom clearance F = face width a (alpha) = addendum angle ß (beta) = dedendum angle
Y (gamma) = pitch angle Ya = back cone angle
Y = root angle
A = addendum B = dedendum C = cone distance D = pitch diameter Da = outside diameter Dr = root diameter E = bottom clearance F = face width a (alpha) = addendum angle ß (beta) = dedendum angle
Y (gamma) = pitch angle Ya = back cone angle
Y = root angle
Fig. 24.24 Bevel-gear terms
(a) Bevel gears
(b) Crown wheel and pinions
The pitch angle is the angle between the axis of the gear and the cone generating line.
The root-cone angle is the angle between the gear axis and the root generating line.
The face angle is the angle between the tips of the teeth and the axis of the gear.
The addendum angle is the angle between the top of the teeth and the pitch-cone generator.
The dedendum angle is the angle between the bottom of the teeth and the pitch-cone generator.
The outside diameter is the diameter measured over the tips of the teeth.
The following figures show the various stages in drawing bevel gears. The approximate construction for the profile of the teeth has been described in the section relating to spur gears.
Gear data: 15 teeth, 20° pitch-cone angle, 100 mm pitch-circle diameter, 20° pressure angle.
Stage 1 Stage 2
Stage 3
Set out the cone as shown in Fig. 24.26. Set out the addendum and dedendum. Project part of the auxiliary view to draw the teeth (Fig. 24.27)
Project widths A, B, and C on the outside, pitch, and root diameters, in plan view. Complete the front elevation (Fig. 24.28).
Vertex
Vertex
Fig. 24.26 Stage 1
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