Clutches are found in equipment drives, where they are used to connect and disconnect shafts. These shafts carry gears or other machine parts that transmit power and motion to the rest of the system. When a certain shaft is engaged to the drive, the drive causes it to spin or move. This movement is then utilized by the equipment to perform its function. In a car, the engine generates power, a clutch engages a shaft to the drive shaft, the clutched shaft begins to spin, and the motion is eventually translated to a force that turns the wheels.
Clutches are not only found in car engines, however. They are important components of most engine/drive systems. In car engines, clutches typically utilize friction discs, which press against one another and transfer power so that different parts can move at different speeds. They also enable a driver to stop a car without shutting down the engine. In a drill, a clutch joins the motor-driven shaft and the shaft that turns the drill chuck, allowing the drill chuck to spin at a different speed than the engine shaft. By disengaging the drill-chuck shaft from the engine shaft, the clutch allows the user to stop the drill without turning it off completely. A clutch, therefore, allows much greater diversity in speeds than possible with only an engine and a single shaft.
A wide assortment of clutches is available for a variety of drive applications. Wet clutches are encased in lubricating fluid, which preserves the parts by lowering operating temperatures, reducing friction and cleaning components. Dry clutches, used in many motorcycles, are not surrounded by oil. This may lead to more noise output at certain settings than would be otherwise encountered when using a wet clutch. In addition to the many drive clutches available, there are also overload, torque and slip clutches. A number of miniature clutches are also used to enhance performance in various systems.
