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ACTIVITY 1:
To be able to describe how a hydraulic system works
[LO 1.3, 2.3]
Pneumatic and hydraulic systems are systems that exert control so that the input-output relationship changes in such a way that tasks can be done faster with less force.
There are two kinds of hydraulic systems:
An open hydraulic system contains a liquid that is placed under pressure, for example water and a garden hose with a pressure nozzle.The system can also contain water that flows in a pipe when there is a difference in pressure, between the two ends of the pipe. Just think of the great advantage this device offers to farmers.
A closed hydraulic system: This consists of a sealed unit containing two pistons that are connected to each other by means of a pipe or reservoir. An input force on the smaller piston is transmitted in all directions by the liquid and imparts an output force on the larger piston. Because the pressure is transmitted in all directions in the liquid, the larger piston can have a greater output because of its larger area. All hydraulic systems work according to this principle.
A syringe can also be used to illustrate the way in which a hydraulic system works.
The piston on which the pressure is exerted, is called the master, or input, piston and the syringe that experiences the effect, is called the server, or output, piston.
In your own words, describe how a hydraulic system works. Also give two examples of hydraulic systems that are commonly used.
ACTIVITY 2:
To examine the transmission of pressure in a hydraulic system and to be able to describe it
[LO 1.3, 2.3]
You need the following items for this research:
2 x 10 mℓ plastic syringes marked A and B
1 x plastic tube
Connect the cylinders as indicated in the figure and fill the system with water.
Wet both ends of the plastic tube and fix it to the syringes as indicated in the drawing.
1. Push the plunger of cylinder I in to a level of 2 cm deep. Make a note of your observation of the distance output in cylinder B.
2. Push the plunger of cylinder B in to a level of 2 cm deep. Make a note of the distance output in syringe A.
3. Has any mechanical advantage been observed?
4. Summary: The transmission of pressure in a hydraulic system.
ACTIVITY 3:
To examine the functioning of a pneumatic system and to compare it with that of a hydraulic system
[LO 1.3, 2.3]
Dry plastic syringes A and B and repeat the investigation done in Activity 2. This time draw up air into the cylinders instead of water.
1. What similarities exist between hydraulic and pneumatic systems?
2. What difference is there between the systems with regard to the effective transmission of the pressure?
ACTIVITY 4:
To examine the influence of the diameter of the piston disc on distance and power output and to be able to discuss it
[LO 1.3, 2.3]
You will need the following items for this investigation:
1 x 10 mℓ cylinder marked A
1 x 20 mℓ cylinder marked C
a tube
Connect the cylinders as indicated in the figure and fill the system with water.
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