Which component controls the safe operating speed of an air motor?

The component that controls the safe operating speed of an air motor is the load. In pneumatic systems, the load affects the performance and efficiency of the air motor. When the load increases, the motor may slow down because it has to work harder to perform the required task. Conversely, if the load is light, the motor can run at a higher speed.

This relationship is crucial because it ensures that the air motor does not exceed its safe operating limits, which could lead to potential damage or failure. By monitoring and adjusting the load, operators can maintain the motor within its designated speed range, ensuring reliable operation and longevity.

The other options do not directly control the speed of the air motor in the context given. The speed reducer, for instance, is typically used to lower the speed of a motor but does not relate to the load principle. Similarly, while a regulator can manage the air supply pressure, it does not dictate the motor's speed in relation to the load it is handling, nor does a limit switch monitor motor speed; it serves more to prevent operation beyond specific physical movement or position limits. Thus, the load is the critical factor in controlling the air motor's safe operating speed.