Final answer:
In engineering applications, a control system that operates by opening and closing electrically operated mechanical switches, such as fly-by-wire in aircraft or switches in heavy machinery, manipulates electrical signals to control mechanical functions.
Step-by-step explanation:
A system control that loads by opening and closing electrically operated mechanical switches is commonly found in various engineering applications. An example of this is the concept of fly-by-wire, which is an aircraft control system where the setting of control surfaces, such as the rudder and ailerons, is handled by electrical signals rather than direct mechanical linkages.
In heavy machinery, like the backhoe illustrated in the referenced figures, both hydraulic and mechanical lever systems can be used for machine controls. The role of the switch in these systems, as depicted in FIGURE 21.41, is to control the electrical circuit. Such a switch is typically in series with a resistance and a voltage source. When the switch is closed, it allows current to flow through the circuit because it presents nearly zero resistance. Conversely, when the switch is open, it interrupts the flow of current by presenting an extremely large resistance.
In the real-world context, such controls can be observed in both open and closed systems, depending on whether they allow interaction with the environment or not. A car, for instance, can be seen as an open system, whereas a spring-operated dart gun may be considered a more closed system.
This system uses electrical signals to control the setting of mechanical switches, such as those used in aircraft control surfaces like the rudder and ailerons. Examples of such systems include fly-by-wire control systems in airplanes.