A pneumatic screwdriver is a tool that is powered by compressed air. Commonly used on an assembly line, the pneumatic screwdriver allows a worker to place many screws without generating forearm or hand fatigue. Available in flat head, Phillips and Torx® head versions, a pneumatic screwdriver can be preset to a certain torque setting to prevent stripping of screw heads or threads due to over-tightening. Unlike a battery-powered screwdriver, the compressed air used to power the pneumatic version typically remains constant and never requires recharging. Common maintenance involves a light application of oil in the air line connection to lubricate the motor as the air flows through.
Many assembly line jobs involve the driving and tightening of screws of one type or another. Using a hand-held and powered screwdriver would not only result in stopping the assembly line to catch up as the worker fell behind, it would result in severe injury to the workers' hands, wrists and forearms. Using a battery-powered screwdriver is better, however, the batteries often fail during use and require charging time or time to change the battery pack. The price of replacement battery packs is also very high. The solution in many assembly plants is the pneumatic screwdriver.
Typically operated from air lines dropped down from the ceiling over the assembly line, the worker simply pulls the spring-loaded pneumatic screwdriver down and drives the required screws by squeezing a handle on the side of the screwdriver body. By hanging the pneumatic screwdriver from above the line, the workers are not tangled in air lines around their feet and the air line is not in the way of the parts or screws. The spring-loaded action of the pneumatic screwdriver pulls the tool up and out of the way as soon as the worker releases the tool, allowing the worker to complete other assembly steps and push the object down the line.
In a high-use position, a foreman or relief worker may change out the pneumatic screwdriver with a replacement during the working shift to allow the old tool to be oiled and, if needed, replace the screwdriver tip. In very busy assembly plants, this may happen at every break period, or there may be scheduled intervals to exchange the tools. While equipped with a clutch that regulates the amount of torque that is applied to the screw, many pneumatic screwdriver operators become so accustomed to the sound of their tool that they can judge the amount of torque simply by the sound the tool makes as it drives the screw home.