In gear design and drafting, bevel gear teeth generally use the same involute tooth geometry used for spur gears, except that the teeth taper toward the cone apex to suit the conical pitch surface. Decide whether this statement is correct.

Introduction / Context:
Bevel gears transmit motion between intersecting shafts (commonly at 90 degrees) using teeth formed on a conical pitch surface. A frequent point of confusion is whether bevel gear teeth share the same involute form as spur gears, and how that form adapts to the cone geometry. This item checks understanding of tooth geometry fundamentals used in production and in technical drawings.

Given Data / Assumptions:

• Spur gears have involute flank profiles developed from a base circle.
• Bevel gears are essentially “spurs on a cone” with tooth size shrinking toward the apex.
• Modern manufacturing (hobbing, milling, face hobbing) targets involute-like action for conjugate motion.

Concept / Approach:
The involute profile ensures a constant velocity ratio when meshing. For bevel gears, the working surfaces are not cylindrical but conical; however, the local tooth sections are still designed to provide involute action. Teeth are proportionally tapered so that, along the face width, the addendum/dedendum reduce toward the cone apex, preserving conjugacy and contact ratio.

Step-by-Step Solution:
1) Identify the desired motion: constant velocity ratio between intersecting shafts.2) Select conjugate flank geometry: involute action is preferred for manufacturability and tolerance robustness.3) Map spur-gear involute logic onto a conical pitch surface, yielding tapered teeth.4) Verify in drawings: specify pitch cone angles, face width, and tooth data consistent with involute-based systems.

Verification / Alternative check:
Standard texts and catalogs describe straight, spiral, and zerol bevel gears using involute-based systems; production methods (e.g., face milling/hobbing) are designed around that geometry to achieve proper rolling action.

Why Other Options Are Wrong:
“Incorrect”: Conflicts with mainstream bevel gear practice.“Only cycloidal teeth…”: Cycloidal forms are historical and uncommon for power transmission bevels.“Straight-sided teeth by rule”: Straight-sided (non-involute) forms would not maintain constant velocity ratio under load.

Common Pitfalls:
Assuming identical cross-sections along the face width; forgetting taper and toe–heel differences; ignoring mounting distance effects on contact.

Final Answer:
Correct