1. CAN YOU HANDLE THE PRESSURE?

2. MOVING THINGS WITH PRESSURE
What is Hydraulics?
The science of transporting of liquids through pipes, especially as motive (motion) power. Nowadays we push fluid through piston and
Pipes to help us do work.
What is Pneumatics?
The science of of transporting of gas/air through pipes, especially as motive (motion) power. Nowadays we push gas/air through piston and

3. HYDRAULIC SYSTEM
A Simple hydraulic system consisting of two pistons and an oil-filled pipe connecting them.

4. FLUID PRESSURE FLUIDS: Materials that flow like liquids & gases
PRESSURE ~ FORCE
FLUID PRESSURE: Exerted in all directions equally
CONFINED FLUIDS: Any fluid in a closed system.
The fluids can move around within the system, but cannot leave or enter the system.
EXAMPLES: Blood moving through the body,
Air moving in a balloon
Pascal discovered that “ the pressure put upon an enclosed fluid is transmitted equally in all directions without loss and acts with an equal intensity upon equal surfaces.”

5. Monica Moreno:
HANDS ON => A great way to experience this is to fill and put two different sized syringes together and press one at a time. It is easy to push the water from a small syringe into a larger one, but much harder the other way! (That’s because force equals pressure times the area, F = P X A). Since the area of the big syringe is larger, the force is multiplied – (the pressure of the water is the same between the two syringes). Take out some syringes and try it!
The larger syringe doesn’t move much though, so while the force is stronger, the movement is less.
FLUID PRESSURE Cont …
The small syringe is easier to push, but it doesn’t
Make much movement in the other one!
The force applied to the small piston produces a greater
Force in a larger piston, but with less movement.
Force on the fluid in a small cylinder (usually supplied by an air compressor) is greatly increased in the “slave” cylinder since the diameter is larger. The only drawback is that the distance the small cylinder must go is greater and
the slave cylinder moves only a short distance.
Small force can move a car!

6. DIFFERENCE BETWEEN HYDRAULICS & PNEUMATICS
Monica Moreno:
HANDS ON => take a syringe, fill it with air, and then cover the open end with your finger.  Show that the air can be compressed by pushing down on the plunger.  Let the students do this, so that they see it is not some sort of trick.  Then fill in the syringe with water. Again covering the end with your finger, show that now you cannot compress the water with all your might.  Try very very hard to make sure they see your effort.  Get students to replicate this.  This also makes for a great whole class experiment / activity.  Make sure you think of some interesting questions and then get the students to experiment / fool around with syringes filled with air and water.  Watch out, because when I did this, lots of the time, the students ended up having a water fight with the syringes - not really a big deal if contained to the classroom though)
DIFFERENCE BETWEEN HYDRAULICS & PNEUMATICS
Hydraulics uses water and pneumatics uses air.
Gases - Very compressible - Gas particles are very spread out
Liquids - Not compressible - Particles in a liquid are not as spread out as in a gas
Monica Moreno: QUESTIONS: If you fill in the syringe with 20mL of air, to what volume can you compress it?             If you fill in the syringe with 20mL of water, to what volume can you compress it?              What is the difference between compressing air and water?              Attach two syringes with some tubing with air in the confined system.  What happens when you press on the plunger? Attach two syringes with some tubing with water in the confined system.  What happens when you press on the plunger?
HOW CAN WE CONTROL THE FLOW OF FLUID? WHAT DIRECTION IT GOES? INTRODUCE VALVES.
Attach two syringes with some tubing and a valve.  What happens when you press on one plunger?        (Lots of things happening here.  The students start getting a feel for hydraulics and pneumatics.  They realize that in hydraulics there is no delay, and the force is passed on instantly to the other syringe, while in pneumatics there is a delay of action because of the compressiblity of gases.  Then you can introduce the valves - T intersection, one way valve, etc. This shows the children different ways of controlling the flow of fluids.  Make sure you relate the valves to something they are familiar with, like a tap in a bathtub, etc.)
Cannot push down on a liquid, cannot compress the liquid.

7. PNEUMATICS
Confined pressurized systems that use moving air or other gases
Because gases can be compressed, there is a delay in the movement, the force
Need for Compressor
HYDRAULICS
Confined pressurized systems that use moving liquids
Liquids are not very compressible, there is not delay in the movement
Hydraulic Fluid: liquid inside system
Cylinder: Container holding liquid
Piston: Plunger moving inside cylinder
Pumps – moves liquid in a specific direction (usually against gravity)
Valves – Controls the flow of direction (allows flow in one direction)

8. EXAMPLES Hydraulics in Everyday Use!
Robotic arms use hydraulics and small motors to make the same movements over and over.
Excavators can be fitted with a pneumatic jackhammer as well.
The arrows show the direction of movement of the pistons. The straight movement of the piston results in curved movement of the arm.
A scissor lift is used as a movable, elevating platform.

9. This simple parallel lifter lifts the platform horizontally.
EXAMPLES CONT …
This simple parallel lifter lifts the platform horizontally.
A scissor lift uses a hydraulic syringe in a different direction. By pushing the plunger, the syringe pushes sideways, this movement is transferred with a lever to an upward motion.
A really simple lifter using one syringe and a platform attached with string.
Simple excavator
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