PORTABLE PNEUMATIC IMPACT WRENCH

BE SURE YOU ARE NOT DAYDREAMING when you use the rotary scaler. Needle scalers accomplish their task with an assembly of individual needles impacting on a surface hundreds of times a minute. The advantage of using individual needles is that irregular surfaces can be cleaned readily. See figure 1-69. PORTABLE PNEUMATIC IMPACT WRENCH The portable pneumatic impact wrench (fig. 1-70) is designed for installing or removing nuts and bolts. The wrench comes in different sizes and is classified by the size of the square anvil on the drive end. The anvil is equipped with a socket lock, which provides positive locking of the socket wrenches or attachments. The wrench has a built-in oil reservoir and an adjustable air valve regulator, which adjusts the torque output of the wrench. The torque regulator reduces the possibility of shearing or damaging threads when installing nuts and bolts to their required tension. Nearly all pneumatic wrenches operate most efficiently on an air pressure range of 80 to 90 psi. A variation in excess of plus or minus 5 pounds is serious. Lower pressure causes a decrease in the driving speeds, while higher pressure causes the wrench to overspeed with subsequent abnormal wear of the motor impact mechanisms. The throttle lever, located at the rear of the pneumatic wrench, provides the means for starting and stopping the wrench. Depressing the throttle lever starts the wrench in operation. Upon release, the lever rises to its original position, stopping the wrench. The valve stem is seated beneath the pivot end of the throttle lever. Most wrenches have a window cut in the throttle lever so that the markings on the upper surface of the valve stem will be visible. Two letters, F and R, have been engraved on the head of the valve stem to indicate the forward (clockwise) and reverse (counterclockwise) rotation of the anvil. To change from forward to reverse rotation, or vice versa, turn the valve stem 180° until the desired marking is visible through the window in the throttle lever. When the valve stem is in proper position, the valve stem pin engages a recess on the underside of the valve stem, preventing accidental turning of the stem. The air valve regulator is located at the bottom and towards the rear of the wrench. Using a screwdriver and altering the setting of the air regulator up to 90°, either to the right or left, reduces the torque from full power to zero power. Before operating the pneumatic impact wrench, make sure the socket or other attachment you are using is properly secured to the anvil. It is always a good idea to operate the wrench free of load in both forward and reverse directions to see that it operates properly. Check the installation of the air hose to make sure it is in accordance with the manufacturer’s recommendation. Figure 1-70.-Pneumatic impact wrench. 1-41 Figure 1-69.-Needle impact scaler.