What is a shaft called that is used to connect or disconnect at will?

The term used to describe a shaft that is designed specifically for the purpose of connecting or disconnecting a mechanical system at will is known as a clutch. A clutch is an essential component in various machinery and automotive applications, allowing for the engagement or disengagement of power transmission without stopping the engine or machinery.

When a clutch is engaged, it connects the rotating shaft to another component, allowing for torque transfer and operational functionality. Conversely, when it is disengaged, it disconnects the shaft, effectively stopping the power transmission while allowing the engine or motor to continue running. This capability is crucial for operations that require shifting gears, stopping motion, or varying speed without a complete system shutdown.

In contrast, bearings are used to reduce friction and support rotating shafts, while a brake shaft is involved in stopping motion rather than connecting or disconnecting it. A lock shaft generally refers to a device that secures another component in place and does not provide the same functionality as a clutch.