Hydraulics and Pneumatics

Hydraulic systems may use a variety of fluids -- ranging from water (with or without additives) to high-temperature fire-resistant types. Again the fluid is different but the operating characteristics change little. Most pneumatic circuits run at low power -- usually around 2 to 3 horsepower. Two main advantages of air-operated circuits are their low initial cost and design simplicity. Because air systems operate at relatively low pressure, the components can be made of relatively inexpensive material -- often by mass production processes such as plastic injection molding, or zinc or aluminum die-casting. Either process cuts secondary machining operations and cost.