Which factor does NOT affect the speed change provided by variable pitch sheaves?

The factor that does not affect the speed change provided by variable pitch sheaves is the material of the pulley. The primary function of variable pitch sheaves is to change the effective diameter of the pulley, which directly affects the speed and torque transmitted through the belt or drive system.

The angle of the groove is critical as it determines how the belt interacts with the sheave, while the pitch of the sheave is essential because it defines the spacing and geometry of the grooves that accommodate the belt. Additionally, the size of the sheave directly impacts the speed ratio since larger or smaller sheaves will change the belt’s travel distance and speed accordingly.

While the material of the pulley can influence durability, wear resistance, and potential friction, it does not inherently change the mechanics of speed change facilitated by the variable pitch system. Consequently, the material itself is not a determining factor in how effectively the speed is altered by the sheave's design and settings.