THE BIG MOVERS – HYDRAULICS

 HOME MADE EXCAVATOR USING SYRINGES AS HYDRAULICS

HOME MADE EXCAVATOR USING SYRINGES AS HYDRAULICS

Most machines that move very large objects use a hydraulic system.

HYDRAULIC SYSTEM:

System that uses a liquid under pressure to move loads.

  • works according to Pascal’s Law.

Before hydraulic systems most construction was done by hand

            Ex) Pyramids, castles, great wall of china

Remember : Pneumatic systems use gases while hydraulic systems use liquids!


PRESSURE IN FLUIDS

 PISTONS OF AN ENGINE

PISTONS OF AN ENGINE

PRESSURE:

Measure of the amount of force applied to a given area.

                        Pressure  (Pa) = Force (N)/Area (m²)

PASCAL’S LAW:

Pressure applied to an enclosed fluid is transmitted equally in all directions through out the fluid.

*this means fluids do not become compressed, unlike gases.

A PISTON CREATES PRESSURE

Hydraulic systems work because of pistons.

PISTON:

A disk that fits tightly inside a cylinder.

  • As the disk moves it either pushes fluid out or draws a fluid in
  • Size can vary

 

Hydraulic system is a combination of 2 pistons attached by a flexible pipe.

 

Small Piston Pressure = Large Piston Pressure

So... We can say that:

Force of the Small Piston / Area of the small piston = Force of the Large Piston / Area of the large piston

Re-written we express it as such: 

F (small)/A (small) = F (large)/A (large) 

 

INPUT PISTON:

Used to apply force to the fluid.

OUTPUT PISTON:

Transfers the force to the load

 

PRESSURE EXERTED EQUALLY IN THE FLUID PROVIDES THE MECHANICAL ADVANTAGE.

Mechanical Advantage (MA) =  Output Force/Input Force

HYDRAULICS QUESTIONS


EVALUATING MECHANICAL DEVICES

Evaluate a mechanical device based on the following criteria:

  • Function
  • Design
  • Effectiveness
  • Efficiency
  • Consider the environment it is being used in
  • Consider if it has potential for development

Evaluate 2 different mechanical devices using the criteria given. 


CSA :

A non-government association that tests and approves a wide range of products to ensure they are safe for use by the consumer. CSA stands for Canadian Standards Association. 


Technological advances and mechanical devices

Technology and devices have come a long way since the invention of simple machines. Advances in technology can have broad implications on human society:

  • Changes in society
  • Changes in the environment
  • Changes in production capacity
  • Changes in human behaviour

Watch the following video and write down all the different changes in society, human behaviour, environment, and production capacity.