Splines are used when which condition is necessary?

• A. The power transmitted is low
• B. The power to be transmitted is high
• C. Axial relative motion between shafts and hub is necessary
• D. Flame hardening

Answer: (C)

Splines are mechanical components that involve a series of ridges or teeth on a shaft that fit into corresponding grooves in a hub. This design is particularly useful when there is a need for axial relative motion, meaning the shafts can slide along their axis while maintaining rotational engagement. This feature is critical in applications where components must be engaged and disengaged frequently, or when adjustments in position are needed while still transmitting torque effectively.

In contrast, the other options pertain to different considerations in mechanical design. Low power transmission typically does not require the robustness of splines, and similarly, while high power transmission may involve various forms of coupling, splines specifically address the dynamics of movement rather than just power levels. Flame hardening, which is a heat treatment process used to harden the surface of metal components, does not relate directly to the function of splines either. Therefore, the accurate condition associated with the use of splines is the necessity for axial relative motion between shafts and hubs, making that choice the most appropriate.