Motor-driven actuators

Eiectricaiiy operated—Jh s actuator converts electricity to mechanical energy. Examples are the solenoid valve and the motor-driven actuator. 

A motor-driven actuator is attached to the stem of a valve by a set of gears. Gear movement controls the position of the stem. 

Actuators for control valves come in three basic designs pneumatic, electric, and hydraulic. Pneumatic actuators, which convert air pressure to mechanical energy, use three designs diaphragm, piston, and vane. Electrically operated actuators convert electricity to mechanical energy. Common examples include solenoid valves and motor-driven actuators. Hydraulically operated actuators convert liquid pressure to mechanical energy. The hydraulic actuator uses a liquid-tight cylinder and piston to move or position the valve stem. 

It is easier to carry than other portable artificial heart systems. It combines two traditional methods to drive pump air-driven and electric motor-driven. The motor-driven actuator generates air pressure necessary to pump blood without any additional air compressor or vacuum pump. 

Automatic filters are made with either viscous-coated or dry filter media. However, the cleaning or disposal of the loaded medium is essentially continuous and automatic. In most such devices the air passes horizontally through a movable filter curtain. As the filter loads with dust, the curtain is continuously or intermittently advanced to expose clean media to the air flow and to clean or dispose of the loaded medium. Movement of the curtain can be provided by a hand crank or a motor drive. Movement of a motor-driven curtain can be actuated automatically by a differential-pressure switch connected across the filter. 

Hydraulic classification ensures the highest separating efficiency obtainable by wet-classification means. The amount of hydraulic water is controlled so that in each succeeding compartment the coarsest particles are maintained in hindered-settling condition and the finer fractions pass along for similar treatment. Two compartments will normally capture 90 percent of a two-screen-size fraction. Spigot discharge is controlled by air-actuated valves in the Jet Sizer and motor-driven pincer-type valves in the SuperSorter. Solid fractions... 

By using automatic position devices, such as stepper motors, DC motors, electrically operated car aerial motors, a combination of pneumatic actuators and motor-driven screw assemblies, and pneumatic elevators, the positions of the sample probe (intermediate and final positions) and duration at each... 

Externally powered assistive system Assistive system for restoration of motor functions that uses external power to control muscles of driven actuators. 

The state-of-the-art connector press is electromechanically actuated, relying on a motor-driven coarse-pitch lead screw with tachometer speed control, z-axis positional encoders, and load cell feedback for an accurate pressing cycle (see Fig. 49.9). 

Comment There are a number of designs that employ pneumatic, hydraulic, or electrical systems to actuate relief valves. Some designs attach directly to the spring-loaded rehef valves and others may use a bah valve combined with a motor-driven operator, such as the one shown in Fig. 5.194. 

Even at 1 Hz, the most popular testing frequency, the results in Figure 26.17 showed a mismatch in magnitude and a more serious one in phase lag (approximately 18 degrees, equivalent to 50 ms) due to the inertia and slower motor-driven flexion actuator compared to the fighter and... 

The HFBR core uses fully-enriched (93%) uranium oxide-aluminum cermet curved plates dad m aluminum. The core height is 0.58 m and the diameter is 0.48 m or a volume of 103.7 Itr. The U-235 weighs 9.83 kg supported by a grid plate on the vessel bottom. The coolant flow u downward. Iience. How reversal is necessary for natural circulation. It operating temperature and pressure are 60 ( and 195 psi. There are 8 main and 8 auxiliary control rod blades made of europium oxide (Lii A)o and dysprosium oxide (DyjO,), clad in stainless steel that operate in the reflector region. The scram system is the winch-clutch release type to drop the blades into the reflector region. Actuation of scram causes a setback for the auxiliary control rods which are driven upward by drive motors,... 

Fig. 3 shows the experimental apparatus. The feed tank had a 50 gallon capacity and was equipped with a variable speed mixer. The feed pump was a flexible impeller, positive-displacement pump to minimize shearing of the feed emulsion. The pumping rate was regulated by a Graham Variable Speed Transmission. Each flotation tank was 11.5 in. ID with 6.5 in. liquid depth maintained by a CE IN-VAL-CO conductometric level controller with a pneumatically actuated control valve in the effluent line. The fourth cell was not equipped with an air inducer. The outer diameter of the air downcomers was 1.5 in. The rotor in each air inducer was a turbine taken from a 2 in. turbine flow meter. Each rotor was belt driven by a 10,000 rpm, 1/30 hp motor and all three motors were governed by the same variable transformer. Another pulley on each rotor shaft was attached to a non-powered belt connecting all three shafts to ensure that each rotor turned at the same speed. 

Fig. 7.9. Batch fluid bed spray granulator used to produce tablet granulations in the pharmaceutical industry. Air-flow necessary for fluidization is generated by a suction-fan (2) mounted in the top portion of the unit, directly driven by an electric motor. The air being used is heated to the desired temperature by an air heater (5). Prefilters remove all impurities at the air inlet (6). The material to be processed has been loaded into the material container (1). The container bottom consists of a perforated plate above which a fine mesh stainless steel retaining screen is fitted. Exhaust filters (7) mounted above the product container retain fines and dust. The granulating liquid (3) is sprayed as a fine mist through a mechanical or pneumatically actuated nozzle (4) onto the finely dispersed, fluidized material to form the desired agglomerates. (Courtesy Aeromatic AG.)...

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