1. Hydraulic & Pneumatic Systems
Pascal’s Principle

2. Pascal’s Principle
“The pressure applied to an enclosed liquid is transmitted equally to every part of the liquid and to the walls of the container.”
In other words, pressure is constant throughout a closed system.

3. Hydraulic Lifts
Used a lot by mechanics to lift cars, hydraulic lifts demonstrate Pascal’s Principle:
So what does this mean?
The larger the area, the larger the applied force.
*Using Pascal’s Principle
*Using P = F / A S L

4. Example #1
A force of 30 N is applied to the end of a small cylinder with an area of 25 cm2 attached to a closed hydraulic system. What is the force on the large cylinder if it has an area of 1 m2?

5. Example #2
What force must be applied to a small cylinder with a radius of 30 cm to lift a car with mass 500kg positioned over a large cylinder with a radius of 1.5m?

6. Hydraulic Brakes (Car)
Another example of Pascal’s Principle:
Brake applies a force to a small cylinder of fluid, increasing pressure.
This pressure is transferred to two large cylinders surrounding a brake disc.
The pads on the end of the cylinders squeeze the disc with a large force until car stops.

7. Homework
P.252 #1-5