Hydraulic Circuits - 2 Backup

7/25/2019 Hydraulic Circuits - 2 Backup

1/13

16thJune, 2013

1 | P a g e

Hydraulic ircuits

Laboratory Report

Kareem Ibrahim Mohamed Nasr

Section: 7

Seat Number: 331


2/13

2 | P a g e

Experiment (1)

Components

1- Tanks

2- Filter

3- Fixed displacement pump

4- Pressure relief valve

5- 4/2 manually operated with detent-spring returned DCV

6- Flow control with check valve (meter out extension)

7- Hydraulic cylinder (actuator)

Experiment objective

Changing the orifice opening of the flow control valve and study its effect in

pressure readings and extension time.

16thJune, 2013


3/13

3 | P a g e

At extension stroke

P1(bar) P2(bar) Text(sec)

9 18 2.658 18 2.69

9 18 2.6920 40 2.6935 65 2.7945 85 3.2548 92 3.45

Comments and conclusions

1- Extension velocity is reduced by closing the valve. Since

there is Less flowrate passing through the orifice.

2- Pressures in the two sides of the cylinders are increased by closing

the valve. Since the Resistance is increasing correspondingly.3- The 1st three readings were not accurate. This may be Caused

by valve leakage or derange.

16thJune, 2013


4/13

4 | P a g e

Components1- Tank

2- Filter

3- Fixed displacement pump

4,5- pressure relief valves

6- 4/3 manually operated with detent spring returned DCV

7. Hydraulic cylinder (actuator)

Calculating the minimumpressurerequireto lift the load

Operation

Change the set pressure of the relief valve (1), And try to lift the load.

The load would only be lifted at set pressure of 34 bar.

So min pressure = Prelief /1.1 = 30.9 bar

16thJune, 2013

Experiment (2)

Objective


5/13

5 | P a g e

Sequential circuits

Parallel connection

Objective

Study the sequential movement of cylinders.

Comments

1. Every cylinder can operate alone and two cylinders in a parallel

connection.

2. When operating the two cylinders the lower load will operate first

3. Tandem center DCV can't be used in this circuit. If such occured

extension or retraction strokes in first cylinder cant be done. Oil

will pass to the tank directly (lower resistance).

16thJune, 2013

Experiment (3)


6/13

6 | P a g e

Series connection

Objective

Study the sequential movement of cylinders.

Comments

1- The4/3DCV must be tandem center to allow extension andretrac-

tion of the first cylinder only.

2- When 4/3 DCV is in the central position,the first cylinder can

be operatedseperately.

3- Two cylinders move together according to DCV positions.

4- The two cylinders didnotachieve the stroke end at the same

time due to leaking or lagging in system.

16thJune, 2013


7/13

7 | P a g e

Pressure intensifier circuitObjective

In this circuit we use double acting hydraulic cylinder acts as pressureintensifier to increase pressure higher than pump pressure for lifting the

load.

Comments

1- Normal circuit can't operate at 25 bar. This is the relief pressure.2- Velocities of lowering and lifting weight will be smaller than

normal circuit.

3- This circuit will operate at a pressure that is lower than 25 bar.

Pressure(bar) Load rising

10 No

12 No

16 Yes

25 bar

16thJune, 2013

Experiment (4)


8/13

8 | P a g e

Pilot operated check valve

Load fixation

Objective

Hold and locking the load at a desired position during stroke with no

fear of leaking circuit components.

16thJune, 2013

Experiment (5)


9/13

9 | P a g e

Hydraulic motor

Objective

Measuring flowrate at different

P.

Results

Flow rate (l/min) Downstream P (bar) Upstream P (bar)

0 0 60

1 0 60

4.5 2 58

10 8 50

In this experimentwe shall connect the pump with motor to make hydro-

motor circuit with its safety devices andmeasuring the fluid quantity at

different pressures.

16thJune, 2013

Experiment (6)


10/13

10 | P a g e

Accumulator

Objective

For the first simple circuit determine the time of the extension/retrac-tion of the cylinder with/without the hydraulic accumulator.

Results

Without ACC. With ACC.

t extension 2.66 1.57

t retraction 1.53 1.14

Comments

1- The cylinder is fasterwhile engaging theaccumulator.

2- The center position must be tandem to chargeaccumulator.

16thJune, 2013

Experiment (7)


11/13

11 | P a g e

Pilot operated check valve

Objective

constructing a hydraulic circuit with pilot operated check valve & trylowering & raising the load with shut off valve slightly by repeatingthe process until the valve fully opening.

Comments

In this circuit the hydraulic cylinder cannot be moved downward by the

pump pressure until the pressure signal open the pilot operated check

valve to open the check valve in reverse direction to make the cylinder

extend.

16thJune, 2013

Experiment (8)


12/13

12 | P a g e

Electro-Hydraulics

Simple circuit

Objective

Constructing an electric circuit to control the hydraulic circuit.

16thJune, 2013

Experiment (9)


13/13

13 | P a g e

Comments

1- Pressure switches which it normally closed and open are used.

2- They sense pressure signal to cut out the electric signal to the

solenoid.

3- The solenoid actuated all time during two stroke by using

another bush button in parallel.

16thJune, 2013

Experiment (10)

Documents

Hydraulic Circuits - 2 Backup