The velocity factor for very accurately cut and ground metallic gears operating at velocities upto __________ are equal to $$\frac{6}{{6 + {\text{v}}}}$$ .

Gear Quality Velocity Range Velocity Factor Formula
Rough cut gears up to 10 m/s
𝐾
𝑣
=
3
3
+
𝑣
K
v
​
=
3+v
3
​

Accurately machined or shaved gears up to 12.5 m/s
𝐾
𝑣
=
4.5
4.5
+
𝑣
K
v
​
=
4.5+v
4.5
​

Precisely ground gears up to 15 m/s
𝐾
𝑣
=
6
6
+
𝑣
K
v
​
=
6+v
6
​

Very high precision gears (special use) beyond 15 m/s Other specialized factors used