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machines and tools they help us to do work but do you know that many of these are pressure

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machines which use either the hydraulic system or the pneumatic system let's first look at the

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hydraulic system but in order to understand what a hydraulic system is and how it works we have to

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know two facts the first fact is that when a liquid is enclosed in a space and a pressure

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is applied to the liquid this pressure is transmitted equally to all parts of the liquid

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this principle is illustrated using this pressure syringe when the piston is pushed down water

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squirts out uniformly in all directions from the holes of the flask the second

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fact is that it is hard to compress a liquid if you try to squash a volume of

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liquid you still have that same volume however hard you try to compress it a

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hydraulic system is one that uses the pressure of a liquid to perform

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mechanical work let's look at this device two syringes a and B of equal

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size are connected by rubber tubing if pressure is exerted at syringe a the

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same pressure will be transmitted over to syringe B we also observed that the

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water from syringe a will move to syringe B as shown by the upward

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movement of the piston in syringe B this demonstrates the two facts which we have

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just discussed that is firstly when a liquid is enclosed in a space and a

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pressure is applied to the liquid this pressure is transmitted equally to all

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parts of the liquid and secondly liquid cannot be compressed the hydraulic

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system makes use of these two facts it can be shown mathematically that if we

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make one of the two pistons much larger than the other then the larger piston

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can raise a larger load the hydraulic system can therefore be considered as a

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force multiplier do you also notice that the small piston has to move a larger

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distance than the large piston in most cases oil is used as the hydraulic

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liquid as it can lubricate the moving parts of the machine as well the

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hydraulic principle is used in many devices like the hydraulic jet used for

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lifting cars at the service station notice that the serviceman has to exert a force on the piston

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many times before the car is raised by a small amount thanks to the hydraulic jack lifting a

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car for servicing is no longer a problem one of the most important components of a car is the

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brake system but do you know that the brake system of a car also works on

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hydraulics let's take a closer look at the brake system of a car when the

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driver presses on the brake pedal the oil in the brake system transmits this

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pressure and moves these pistons this will cause the brake pads to press

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against the rotating disc of the wheel.

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Hydraulics is also used in many heavy machinery in the construction industry, like this loader.

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Can you see the moving pistons in action?

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Machines using the hydraulic system are capable of moving very heavy loads.

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This is a dumper.

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It also works on hydraulics.

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The excavator is another hydraulic machine commonly found at construction sites.

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The hydraulic system will cause pistons to move a part of the machine back and forth.

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Imagine what it would be like if all this work had to be done without the help of these

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hydraulic machines.

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An accident?

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Thank goodness it's only a practice for the Civil Defence Officers.

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They're trying to rescue