How Hydraulic and Pneumatic circuit works

This course is useful for Mechanical engineering students and the students will easily trace the hydraulic and pneumatic circuit after going through these lectures. It is assumed that the students are having the basic knowledge of hydraulic and pneumatic components , their symbols and basic working .

The course is divided into three sections : The first one is about the working of hydraulic and pneumatic circuit , second one is working of some typical hydraulic circuits and third one is about working of some typical pneumatic circuits.

Unloading valve circuit video explains the working of punch press circuit using unloading valve. This hydraulic circuit is also known as High-low double pump system used in punch press application. It uses unloading valve, 4/3 manually operated, spring controlled D.C. valve & two pumps P1 & P2. Pump P1 is constant low volume, high pressure pump whereas pump P2 is variable high volume, low pressure pump. Due to back pressure generated in the circuit, the unloading of the pump P2 takes place through unloading valve.

Deceleration circuit : A deceleration valve is a cam operated shut off valve which is normally open type valve. This circuit is used to decelerate machine table movement at certain points when work is performed on work piece.

The regenerative circuit is used to increase the out-stroke speed of piston of a double - acting cylinder. In this circuit, the fluid from the rod end of the cylinder regenerates with the pump flow. Due to this volume of the fluid supplied to blind end of the cylinder is greater than the pump flow rate.

How to trace pneumatic circuit in case of working of single acting cylinder of a pneumatic circuit. Logic AND control is used in the pneumatic circuit to operate the single acting cylinder. It uses two 3/2 D.C. valves arranged in series and a single acting cylinder.