Question

Minimum no. of teeth requirement an involute gear can be reduced by which of the following modification?

• A. By reducing the centre distance
• B. By increasing the centre distance
• C. By decreasing the pressure angle
• D. None of the above

Answer 1

The correct option is B By increasing the centre distance

On increasing the centre distance, pressure angle increases. Use of a larger pressure angle can eliminate interference.

Having a larger pressure angle results in a small base circle $(r_b=r\cos \phi$).

As a result, more of the tooth profiles become involute. In this case, the tip of the tooth of one gear will not have a chance to contact the flank of the other gear on its non-involute portion. Therefore gears are generally produced wide larger pressure angle of ${20}^{\circ }$ with full depth involute system .