122 Industrial Robotics Fundamentals Copyright Goodheart-Willcox Co., Inc. 6.1.4 Load As stated earlier, the load is a part (or parts) designed to produce work. Work occurs when energy is transformed into mechanical motion, heat, light, chemical action, or sound. Normally, the largest portion of energy supplied by the source is consumed by the load device. Loads include electric motors, heating systems, lighting systems, alarms, horns, and mechanical actuators. 6.1.5 Indicators The indicator is a subsystem that displays information about operating conditions r at various points throughout the system. Some types of indicators include digi- tal meters, pressure gauges, tachometers to measure speed, and thermometers to measure temperature. In some systems, the indicator is optional. In other systems, indicator readings are essential. When operations or adjustments are critical, indi- cator readings may affect how the robot functions. 6.2 Mechanical Systems Mechanical systems transfer power from one point to another through mechani- cal motion that is used to do work. Automated applications use three kinds of motion: rotary (motors), linear (relays, actuators, and cylinders), and reciprocating (certain types of motors and cylinders). The energy source for these motions can be either electrical power or fl uid power (hydraulic or pneumatic). The energy fl may be used to operate motors, relays, solenoids, actuators, or cylinders. As in other systems, the load is responsible for performing this action. Industrial loads are usually designed for continuous operation over long periods of time. The basic mechanical unit, such as the robot’s manipulator, has several moving joints and performs the actual work function of the machine. The transmission path of a mechanical system transfers power from the energy source to the rest of the system. The transmission path may consist of elec- trical conductors, belts, rotating shafts, pipes, tubes, or cables. For example, the power from an electric motor may be transferred by a belt or gear to operate a machine tool. Control is accomplished by changing pressure, direction, force, and speed. Pressure regulators, valves, gears, pulleys, couplings, brakes, and clutches are used to control variables such as force, speed, and direction. Such changes alter the performance of the system, allowing adjustments to be made that optimize the functionality of the system. In a mechanical system, indicators measure physical quantities. These physi- cal quantities include pressure, fl ow rate, speed, direction, distance, force, torque, fl and electrical values. Many of these quantities must be monitored periodically. Some indicators are used to test system conditions during maintenance. Others are designed to measure physical changes that take place. Some examples of indi- cators are pressure gauges flow meters tachometers to measure speed anemom- fl eters to measure wind direction and multimeters to measure electrical voltage, current, and resistance. A warehouse conveyor system is an example of a mechanical system. A con- veyor moves materials, such as boxes, from one location to another. The energy source for a conveyor system is typically an electric motor. The transmission path