Industrial Fluid Power
Experiment 1: Demonstration of meter in and meter out circuit.
Aim: To demonstrate and study the working of Meter-In and Meter-Out
hydraulic circuits.
Apparatus required:
• Hydraulic trainer kit
• Hydraulic pump
• Direction control valve (DCV)
• Flow control valve (FCV)
• Pressure relief valve (PRV)
• Double-acting cylinder
• Hydraulic oil
• Connecting hoses
Theory:
In hydraulic systems, flow control is crucial to regulate the speed of actuators
(like cylinders). Two commonly used circuits are:
• Meter-in Circuit:
1. The flow control valve is placed before the actuator (inlet line).
2. It controls the flow of oil entering the actuator, thus controlling its
extension speed.
3. Suitable for use in high-pressure applications like milling
machines, surface grinding machines, shaping machines, etc.
• Meter-out Circuit:
1. The flow control valve is placed in the outlet line of the actuator.
2. It controls the oil flow leaving the actuator, thus regulating
retraction speed.
3. Suitable for use in drilling machines, boring machines, reaming
and tapping operations, etc.
Procedure:
• Meter-in Circuit:
1. Connect the hydraulic trainer kit components as per the meter-in
circuit diagram.
2. Connect the flow control valve in series before the actuator (on
the inlet line).
3. Start the pump and operate the direction control valve to activate
the cylinder.
4. Gradually adjust the flow control valve and observe the extension
speed of the cylinder.
5. Note the behaviour under load if applicable.
• Meter-out Circuit:
1. Modify the circuit so the flow control valve is connected after the
actuator (on the return line).
2. Start the pump and activate the DC valve to operate the cylinder.
3. Adjust the flow control valve and observe the retraction speed.
4. Note the performance under different load conditions.
Observation Table:
Results:
• The meter-in circuit effectively controlled the extension speed of the
cylinder.
• The meter-out circuit efficiently managed the retraction speed,
especially under load conditions.
Precautions:
• Ensure all hydraulic connections are tight to prevent leakage.
• Do not exceed the rated pressure of the components.
• Avoid sudden changes in the direction control valve.
Diagram:
Experiment 2: Demonstration of sequencing circuit.
Aim: To demonstrate the working and operation of a sequencing circuit.
Apparatus required:
• Hydraulic Pump
• Hydraulic Reservoir
• Directional Control Valves (DCVs)
• Sequencing Valves
• Double-Acting Cylinders (2 nos.)
• Check Valves
• Pressure Gauges
• Hydraulic Hoses and Fittings
Theory:
A sequencing circuit in hydraulics ensures that two or more actuators (usually
cylinders) operate in a predetermined order automatically without manual
intervention.
This is typically achieved using sequence valves, which are pressure-operated
valves that allow flow only after a certain pressure is reached (i.e., after the
first actuator completes its operation).
Procedure:
• Connect the hydraulic pump outlet to the DCV inlet port using hydraulic
hoses.
• Connect the first double-acting cylinder (Cylinder A) to one of the
output ports of the DCV.
• Install a sequencing valve in the line between the DCV and Cylinder B.
• Connect the second double-acting cylinder (Cylinder B) downstream of
the sequencing valve.
• Install check valves where necessary to ensure proper one-way fluid
flow.
• Connect pressure gauges near both cylinders to monitor pressure build-
up and drops.
• Start the hydraulic pump and operate the DCV to supply pressure to the
circuit.
• Observe:
1. Cylinder A should extend first.
2. Once Cylinder A finishes its stroke and pressure builds up, the
sequence valve opens.
3. Then Cylinder B should extend.
• Reverse the DCV to retract both cylinders in the desired sequence.
Observation Table:
Results:
The sequencing valve successfully controlled the sequential movement of two
double-acting cylinders based on pressure build-up, demonstrating the
concept of hydraulic sequencing.
Precautions:
• Ensure all hydraulic connections are tight to avoid leakage.
• Set the sequencing valve pressure appropriately.
• Do not exceed the recommended pressure for cylinders.
Diagram:
Experiment 3: Demonstration of hydraulic circuit for shaper machines.
Aim: To study and demonstrate the working of a hydraulic circuit used in a
shaper machine.
Apparatus required:
• Hydraulic pump
• Hydraulic reservoir
• Double acting hydraulic cylinder
• Direction control valve (DCV) – 4/2 or 4/3
• Flow control valve (FCV)
• Pressure relief valve (PRV)
• Pressure gauge
• Connecting hoses
Theory:
A shaper machine is used for producing flat surfaces, grooves, and slots. In a
hydraulic shaper, instead of mechanical linkages, a hydraulic circuit controls
the reciprocating movement of the ram.
The hydraulic pump draws fluid from the reservoir and sends it under pressure
to the direction control valve. Based on the position of the valve, the fluid
enters either side of the double-acting cylinder, making the ram move forward
(cutting stroke) or backward (return stroke).
Procedure:
• Connect the hydraulic pump to the oil reservoir and to the direction
control valve using hydraulic hoses.
• Connect the outlets of the direction control valve to the two ports of the
double-acting cylinder.
• Install a flow control valve in the circuit to regulate the speed of the ram
stroke.
• Attach a pressure relief valve between the pump outlet and the reservoir
to maintain safe pressure levels.
• Attach a pressure gauge at the pump outlet to monitor system pressure.
• Power ON the electric motor to run the hydraulic pump.
• Operate the direction control valve to move the shaper ram forward
(cutting stroke) and backward (return stroke).
• Adjust the flow control valve to vary the ram speed and observe the
changes.
Observation Table:
Results:
The hydraulic circuit successfully demonstrated the reciprocating motion of a
shaper machine using hydraulic power.
Precautions:
• Ensure there are no leakages in the hydraulic connections before
starting.
• Do not exceed the rated pressure of the hydraulic system.
• Operate valves smoothly to avoid pressure surges.
Diagram:
Experiment 4: Demonstration of pneumatic circuit for speed control of
double acting cylinders.
Aim: To demonstrate and study the pneumatic circuit used for speed control
of a double-acting cylinder.
Apparatus required:
• Double acting pneumatic cylinder
• Flow control valve (one-way)
• Direction control valve (5/2 way DCV)
• Air compressor
• Pressure gauge
• Pneumatic hoses and connectors
• FRL unit (Filter-Regulator-Lubricator)
Theory:
In pneumatic systems, speed control of a double-acting cylinder is achieved
by controlling the rate of airflow into or out of the cylinder using flow control
valves. The double-acting cylinder uses air pressure to move in both
directions (extension and retraction). A 5/2 direction control valve is used to
control the direction of airflow.
By placing flow control valves in the exhaust or inlet lines, we can adjust the
flow of air, thereby controlling the piston speed in either direction.
Procedure:
• Set up the pneumatic circuit on the trainer board as per the diagram.
• Connect the FRL unit to the air compressor and set the desired pressure
(usually 4–6 bar).
• Connect the 5/2 direction control valve to the double-acting cylinder.
• Place one-way flow control valves at the exhaust ports to control the
flow rate.
• Slowly operate the DCV and observe the cylinder’s extension and
retraction speed.
• Adjust the flow control valves and note the variation in piston speed.
• Repeat the process for both directions (forward and return strokes).
• Record your observations.
Observation Table:
Results:
The speed of the double-acting pneumatic cylinder was successfully
controlled using flow control valves.
Precautions:
• Do not exceed the pressure rating of the components.
• Ensure the compressor is switched off before modifying the circuit.
• Check the flow direction arrow on the flow control valve.
Diagram:
Experiment 5: Demonstration of pneumatic circuit for speed control of
pneumatic motor.
Aim: To demonstrate the speed control of a pneumatic motor using a
pneumatic circuit.
Apparatus required:
• Pneumatic motor (air motor)
• Air compressor
• FRL unit (Filter, Regulator, Lubricator)
• Flow control valve (needle valve)
• Direction control valve (DCV – typically 3/2 or 5/2)
• Pressure gauge
• Pneumatic tubing and connectors
• Stop watch or tachometer
Theory:
Pneumatic motors convert compressed air energy into mechanical rotational
motion. The speed of a pneumatic motor can be controlled by regulating the
airflow into the motor using a flow control valve. A throttle-type speed control
method is commonly used, where the flow of air is restricted at the inlet
(supply side) or the exhaust side.
Procedure:
• Connect the FRL unit to the air compressor outlet to ensure clean and
regulated air supply.
• Connect the FRL output to the direction control valve.
• Connect the output port of the DCV to the pneumatic motor.
• Install a flow control valve either at the inlet or exhaust of the pneumatic
motor to control the speed.
• Switch ON the air compressor and set desired pressure using the
pressure regulator.
• Operate the DCV to start the motor.
• Adjust the flow control valve and observe the change in motor speed.
• Measure and record the speed of the motor using a tachometer or a
stopwatch (for a fixed number of revolutions).
• Repeat the process with different flow settings.
Observation Table:
Results:
The speed of a pneumatic motor decreases with the reduction of airflow using
a flow control valve. Hence, the motor speed is successfully controlled by
adjusting the airflow in the pneumatic circuit.
Precautions:
• Ensure all connections are tight and leak-proof.
• Do not exceed the rated pressure for the pneumatic motor.
• Always release compressed air after the experiment.
Diagram:
Experiment 6: Study of trouble shooting procedures of various hydraulic
and pneumatic circuits.
Aim: To study and understand common troubleshooting procedures and
techniques used to diagnose and fix problems in hydraulic and pneumatic
circuits.
Apparatus required:
• Hydraulic trainer kit
• Pneumatic trainer kit
• Air compressor and hydraulic pump
• Flow control valves, pressure relief valves, DCVs
• Hoses, connectors, actuators (cylinders or motors)
• Pressure gauge
• Multimeter (for electro-pneumatics/hydraulics)
Theory:
Hydraulic and pneumatic systems use fluids (liquid or gas) to transmit power.
Over time, faults may occur due to wear, leakage, contamination, or incorrect
settings. Troubleshooting involves identifying and solving these faults
systematically. Common problems in circuits are:-
Procedure:
• Set up the circuit as per the standard hydraulic/pneumatic diagram.
• Check all connections for tightness and proper fit.
• Run the system to observe normal working conditions.
• Introduce artificial faults (like closing a valve, loosening a connection,
blocking exhaust). Then observe system’s abnormal behaviour.
• Check for leakage, disconnected hoses, broken components.
• Use gauges to verify correct pressure levels at various points.
• Manually operate valves to check responsiveness.
• Observe cylinder extension/retraction.
• Check for blocked or restricted flow paths.
• Tighten loose fittings, replace damaged hoses, clear blockages, reset
pressure settings, or replace faulty components.
• Once faults are corrected, restart the system and check whether the
system returns to the normal condition or not.
Observation Table:
Results:
Various faults in hydraulic and pneumatic circuits were successfully
simulated and diagnosed.
Precautions:
• Ensure all equipment is de-energized before manual inspection.
• Use safety goggles and gloves during testing.
• Maintain the correct pressure and oil levels in the system.
Experiment 7: Selection of circuit components for simple hydraulic and
pneumatic circuits.
Aim: To study and understand the selection of appropriate components
required to design basic hydraulic and pneumatic circuits.
Apparatus required:
• Pneumatic and hydraulic trainer kits
• Cylinders (single/double-acting)
• Direction Control Valves (3/2, 5/2, 4/2 DCVs)
• Flow Control Valves
• Pressure Relief Valves
• Air compressor and hydraulic pump
• Tubing and connectors
• FRL unit (for pneumatic system)
• Pressure gauges
Theory:
Hydraulic and pneumatic systems are used to transmit power using
pressurized fluids or compressed air. Proper selection of components is
crucial for efficient and safe operation. Key factors to consider include:
• Type of actuator: linear (cylinder) or rotary (motor)
• Pressure and flow rate requirements
• Control method
• Load
• Speed control needs
Procedure:
• Identify the application: e.g., single-acting cylinder operation.
• Select appropriate actuator: single-acting or double-acting cylinder
based on requirement.
• Choose control valve:
1. For single-acting: use a 3/2 DCV
2. For double-acting: use a 4/2 or 5/2 DCV
• Select power source:
1. Pneumatic: air compressor with FRL unit
2. Hydraulic: hydraulic pump with reservoir
• Add flow and pressure control valves to regulate speed and pressure.
• Connect components using suitable tubing and fittings.
• Verify circuit diagram for proper functionality and flow path.
• Test the circuit after assembly to ensure proper selection and operation.
Observation Table:
Results:
Components were successfully selected and assembled for a simple
hydraulic/pneumatic circuit based on system requirements and application.
Precautions:
• Select components according to pressure and flow ratings.
• Ensure compatibility of all fittings and connectors.
• Avoid over-pressurizing the system.
