Engineering Solution

It defines basic terms and reviews the basic principles of fluid power systems. The term fluid is used for either gases or liquids, this being because both can flow freely. Gases and liquids under pressure can be used to transmit energy over long distances, such systems being referred to as fluid power system. Pneumatics is the term used when compressed air is the fluid and hydraulics when the medium is a liquid, typically oil, under pressure.

Hydraulic system tend to be used at much higher pressure than pneumatic system and consequently can produce much larger force and torques, both, however, tend to be more readily used for large force and torques, than electromagnetic system such as electric motors. Often pneumatics and hydraulics are combined with electrical/electronic systems, these being used to provide the control signals. This and programmable logic controllers are discussed in control system, can be developed with solenoid valves, sensors and programmable logic controllers.

Production and Distribution of Fluid Power System:

This system is concerned with the equipment used for the generation of fluid power and its distribution. For pneumatics this involves a consideration of common forms of compressors, conditioning of the air to remove contaminants, the use of air receivers to enable constant air pressure to be maintained, the layout of pneumatic power system and the sizing of pipes used. With hydraulics, the types of pumps commonly used, conditioning, the role of accumulators and plant layout are discussed.

In this discussing compressors and air distribution, the term “free air” is often uses. Free air is defined as air at normal atmospheric pressure, i.e. at a pressure of 101.3 kPa. Compressors, for example, are specified in terms of the free air delivered (f.a.d), this being the volume a given quantity of compressed air would occupy at atmospheric pressure and the same temperature. This enables comparisons between compressors to be more easily made. The gas laws can be used to convert “free air” to other pressures and/or temperatures or vice versa.

Actuators System:

This is a discussion of fluid power actuators. An actuator is a device that is used to apply a force to an object, and hence possible motion of that object.

Fluid power actuators can be classified in two groups:

1-      Linear actuators are used to move an object or apply a force in a straight line. The basic linear actuator is a cylinder of the form shown, Linear actuator can be divided into two types , single-acting cylinders and double-acting cylinders. A single-acting cylinder is powered by fluid for the movement of the piston in one direction with it being returned in the other direction by an internal spring or an external force, a double-acting cylinder is powered by fluid in both directions.

2-      Rotary actuators are used to move an object in a circular path. Rotary actuators are the fluid power equivalent of an electric motor.

Sensors System:

The term sensor is used with instrumentation and control systems to describe the element which takes information about the variable being measured or monitored and changes it into some form which enables the rest of the measurement or control system to utilize it. This is a brief consideration of the sensor that are commonly used with pneumatics and hydraulic system for position sensing and how they might be used.

With machine control they take information about the positions of, say, some machine element and transform it into a suitable form for the pneumatic or hydraulic system.

Logic Systems:

A logic system is one in which occur in a reasoned sequence. We can think of such a system as involving an array of on-off switches and the condition for an outcome depends on which of the switches are activated. Logic-switching circuit can be developed with electrical, electronic or pneumatic/hydraulic systems. In this logic system the basic mathematics necessary to analyses and synthesis such circuits are introduced.

The mathematics involved is named after George Boole (1815-64), who first developed the modern ideas of the mathematics concerns with the manipulation of logic statements, and is termed Boolean algebra.    

Maintenance and fault finding System:

This is a review of maintenance and fault-finding procedures that are used with pneumatic and hydraulic systems and with PLC controlled systems.

With all such procedures, due care and attention must be given to safety and the relevant regulations followed. In Britain, all industrial processes are governed by the Health and Safety at Work Act 1974.

This places duties on employers to, among other matters:

1-      Provide and maintain safe plant and system of work.

2-      Make arrangements for ensure safe use and handling of articles and substances.

3-      Provide adequate information, instruction, training and supervision.

4-      Maintain a safe place of work.

Duties are places on empolyees to, among other matters:

1-      Safeguard himself/herself and others by using equipment in a safe manner and following safe working practices.

2-      Cooperate with the employer in respect of health and safety matters.

3-      Use equipment and facilities provides to ensure safety and health at work.