23 POWER, FORCE AND POSITIONING DEVICES-NAMLEY, CYLINDERS AND ACTUATORS; PNEUMATIC CONTROLLING DEVICES-NAMELY, DIRECTIONAL AND PRESSURE REDUCING VALVES AND GOVERNORS; HYDRAULIC DEVICES-NAMELY, POWER BOOSTERS AND DIRECTIONAL VALVES; SIGNAL DEVICES-NAMELY, AIR PRESSURE SWITCHES AND PNEUMATIC HORNS; MOTOR AND STEAM DRIVEN COMPRESSORS AND ACCESSORIES THEREFOR; MARINE CONTROLS-NAMELY, CONTROL STANDS, FUEL RACK TRANSMITTORS, GEAR CONTROL CYLINDERS, PANEL BOARDS, PROPELLOR AND STEERING CONTROL UNITS; PULSATION DAMPERS; AND LUBRICATING UNITS