Chapter 9 :Hydraulics and Pneumatics

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Chapter 9 Hydraulics and Pneumatics
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What we will learn this chapter

• Hydraulic systems are systems that use a liquid
  under pressure to transmit a force and do work.

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Liquids cannot be compressed because the
particles are already close together
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This means that liquids can be used to send
forces from one place to another in hydraulic
systems
Liquids cannot be compressed because the
particles are already close together
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Liquids and Compression

• Liquids CANNOT be compressed by ordinary means.
• When pressure is applied to liquid in a pipe ,
  the force can be transmitted over a distance.
• Example A long hose is connected to a water tap
  from the side of a building. Pressure is
  transmitted along the hose and forces the water
  out the other end of the hose.

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Using Pascals Principle

• Hydraulic devices

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Hydraulic systems

• Use liquids to transmit pressure in a confined
  fluid
• A hydraulic system multiplies force by applying
  the force to a small surface area. The increase
  in pressure is then transmitted to another part
  of the confined fluid, which pushes on a larger
  surface area

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Basic Hydraulic System

• 1) a pump, which creates pressure for the system,
  and
• 2) a rotor or cylinder, which transfers the
  hydraulic energy back into mechanical energy in
  the form of rotary or linear motion.

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Hydraulic systems
Force 20N
Force 10N
Y
X
Area 10cm2
pressure
force
Area 40cm2
area
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Examples

• Car brakes
• Dump truck lift
• Hydraulic lifts raise cars off the ground
• Video

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• Why is a leak in a hydraulic system a problem?
• Answer In order for pressure to be transmitted
  in a fluid, the fluid must be confined. If the
  hydraulic system is leaking, the fluid is not
  confined.

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• Hydraulic brakes
• The brake system multiplies the force, so a
  person can stop a large car with only a light
  push on the brake pedal

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Pneumatic Systems

• Pneumatic system a system that uses a gas,
  usually air, under pressure to transmit a
• force.
• In order for a gas to be put to work in a
  fluid system, it must be compressed

• Examples
• Bus ramps
• Bus doors
• Dentist drill
• Nail gun
• Lungs
• Scuba gear
• Video