What is the difference between gear tooth clearance and backlash? ...

[LaDunn]

What is the difference between gear tooth clearance and backlash?
 
  What will be an ideal response?

Question 2

Most new gear drive applications use a ___ degree pressure angle.
 
  What will be an ideal response?

[s.meritte]

Answer to Question 1

Clearance is defined as the distance between the top of the tooth of one gear and the bottom of the meshing tooth space. (See figure 9-10). Backlash is the amount of side clearance of a gear tooth when two teeth mesh. More specifically, it is the space between meshing teeth measured at the pitch circle.

Answer to Question 2

The 20 pressure angle gives the gear tooth a wider base, resulting in greater strength and allows the use of smaller gears with fewer teeth for more compact and economical gear drives.