What does the term "spline" refer to in the context of transmissions?

In the context of transmissions, the term "spline" specifically refers to a connecting feature for gears. Splines are ridged or grooved sections on a shaft or component that allow two parts, such as gears, to fit together in a precise manner. This design enables the transmission of torque while ensuring alignment between the components. The engagement of splines ensures that rotational motion can be transferred without slippage, which is critical in mechanical systems where gears operate under load.

Understanding splines is crucial because they play a significant role in the assembly and functionality of various drivetrain components, ensuring they work harmoniously within a manual transmission system. While other terms mentioned in the choices may relate to different aspects of mechanical systems, it is the splines that serve a direct purpose in connecting gears within transmissions.