Answer: a pneumatic circuit for operation of two DA cylinders such that one operates after other using travel dependant sequencing as shown in fig.
Pressure-relief valve.Pressure-reducing valve. Unloading valve Counterbalance valve Pressure-sequence valve Brake valve.
Counterbalance valves are commonly used to counterbalance a weight or external force or counteract a weight such as a platen or a press and keep it from freefalling.Figure1.16 illustrates the use of a counterbalance or back-pressure valve to keep a vertically mounted cylinder in the upward position while the pump idles, that is, when the DCV is in its center position. During the downward movement of the cylinder, the counterbalance valve is set to open at slightly above the pressure required to hold the piston up (a check valve does not permit flow in this direction).
Time delay valve function : In certain applications like machining or press operation it is necessary that certain operation be delayed by some fraction even after pressing valve. This objective is achieved by Time delay valve.
In all pneumatic power tools like screw drivers, angle grinders, straight grinders. To rotate conveyor belts in food industry. Power device in printing press machine Agitators and mixers Vibrators. symbol for variable speed bidirectional air motor
Merits: 1)Well equipped with quick connect or disconnect end fitting 2)Can be manufactured in long lengths 3)Capable of withstanding to very high pressures. 4)They can absorb very heavy shocks tha rigid tubes. Demerits: 1) Very poor in abrasion resistance 2) Poor in resisting whether condition. 3) Initial cost is very high 4) They can damage due to incompatible oil
FRL Unit: It is service unit used in Pneumatic system which is combination of three devices named as Filter, Regulator and Lubricator. Function of FRL unit Filter (F) – 1) To remove the micron and sub-micron particles present in the entering air of compressor. It is Used to separate out contaminants like dust, dirt p[articles from the compressed air Regulator (R) – In pneumatic system the pressure of compressed air may not stable due to possibility of line fluctuation. Hence there is a need to maintain and regulate the air pressure. This function is performing by regulator.
