Using schematic symbols as building blocks, you can construct a functional diagram showing piping arrangements and operation of any hydraulic or pneumatic circuit.
A number of circuits are used frequently in fluid power systems to perform useful functions. For example, metering circuits offer precise control of actuator speed without a lot of complicated electronics, decompression circuits reduce pressure surges within a hydraulic system by controlling the release of stored fluid energy, and pump-unloading and regenerative circuits make a system more energy efficient. Other circuits are designed for safety, sequencing of operations, and for controlling force, torque, and position. Still other circuits may enhance the application of specific components, such as pumps, motors, accumulators, filters, and airline lubricators.
The circuits appearing on the following pages are provided as a resource of general ideas. They may be used as:
- an educational resource to aid understanding of circuits already in use
- a starting point for new designs, and
- as a modification to enhance operation of existing equipment.
They certainly do not have to be implemented as shown. In fact, many of the circuits use purely mechanical components, so incorporating them into new or retrofit applications may involve integrating electronic feedback and control into the circuit as a modern alternative to mechanical control. However, many existing and new applications still gain the greatest benefit from mechanical control - especially those applications where electricity could pose a threat to health and safety.
However, whether using mechanical control or electronic, perhaps the greatest benefit may be gained by customizing one of these circuits to serve the specific requirements of an application.
Basic circuits used in fluid power systems