Fluid power is present everywhere in nature; it can be either in the form of liquid (water, oil) or compressed air. Engineers have harnessed these powers to design and control machinery. These are now termed as technologies, namely “Hydraulics” and “Pneumatics”.
Case Study 1
A push button is to control the forward stroke. After the piston rod has reached the forward end position, the components are to pressed together for 20 seconds. The cylinder must then return to its initial position.
The return stroke must occur even if the start push button is kept pressed continuously. A new start signal must only become effective, after the initial position has been reached and the push button has been released.
Case Study 2
Furnace Door Control
A Furnace door is opened and closed by a double acting cylinder. The cylinder is activated by a4/2 way valve with spring return. This ensures that the door opens only as long as the valve is actuated. When the valve actuating lever is released, the door closes again.
Case Study 3
A special machine is used to emboss graphic symbols on metal foil. The foil is fed through the embossing machine with an adjustable cycle time. The downward motion of the stamp must be capable of being varied in accordance with the feed speed. The return motion must always be executed as a rapid traverse.
A one-way flow control valve is used to control the speed of the stamp, while a pressure relief valve is used to prevent the weight of the stamp from pulling the piston rod out of the cylinder. A 4/2 way valve is used to switch between upwards and downwards motion.