What type of coupling allows for no shaft misalignment?

The type of coupling that allows for no shaft misalignment is known as a rigid coupling. Rigid couplings are designed to connect two shafts in a manner that maintains their alignment with precision, ensuring that torque is transmitted without any play or gaps. This makes them ideal for applications where exact rotational alignment is crucial, such as in high-speed machinery or precision equipment.

In contrast, the other types of couplings mentioned serve different purposes. Flange couplings, while robust and used in many applications, can accommodate some misalignment but are typically not designed for complete rigidity. Oldham couplings are specifically designed to allow for some angular and axial misalignment between shafts while still transmitting power. Universal couplings, on the other hand, are used to connect shafts that may not be perfectly aligned and allow for significant angular misalignment, making them unsuitable for applications requiring precise alignment.

Thus, rigid couplings stand out as the appropriate choice when the goal is to eliminate any shaft misalignment.