1. Hydraulics
Used in many applications in industry!

2. Hydraulics
An area of engineering science that deals with liquid flow and pressure
Use syringes to demonstrate the basic concept of hydraulic flow

3. Hydraulic Fluids Liquid pumped through a hydraulic system
Petroleum-based or synthetic oil
Serve four major functions:
1. Power transmission
2. Lubrication of moving parts
3. Sealing of spaces between moving parts
4. Heat removal
Relatively Incompressible!
Four major functions:
Power transmission:
Pumps apply pressure to hydraulic fluids, which causes the fluid to move (since they can’t be compressed). This movement causes components connected to the hydraulic system to move. Thus, power is transmitted.
Lubrication of moving parts:
Hydraulic systems provide their own lubrication!
Sealing of spaces between moving parts:
Hydraulic pressure between moving parts (e.g. piston) makes a seal between those parts.
Heat removal:
Hydraulic fluids move passed hot components and then carry that heat away via conduction mechanisms.

4. Two Types or Conditions of Hydraulic Systems
Hydrostatic
Hydrodynamic
Four major functions:
Power transmission:
Pumps apply pressure to hydraulic fluids, which causes the fluid to move (since they can’t be compressed). This movement causes components connected to the hydraulic system to move. Thus, power is transmitted.
Lubrication of moving parts:
Hydraulic systems provide their own lubrication!
Sealing of spaces between moving parts:
Hydraulic pressure between moving parts (e.g. piston) makes a seal between those parts.
Heat removal:
Hydraulic fluids move passed hot components and then carry that heat away via conduction mechanisms.

5. Hydrostatics - a “No Flow” Scenario
“Static” means “stationary” or “non flowing” in a hydraulic system
Hydraulic systems are considered static when there is no flow
Pascal’s Law (for hydrostatics):
a pressure applied to a confined hydrostatic fluid is transmitted with equal intensity throughout the fluid
Same pressure throughout!

6. Hydrodynamics – a “Flow” scenario
“Dynamic” means “moving” or “flowing” in a hydraulic system
Hydraulic systems are considered dynamic when there is flow
Pascal’s Law does not apply!
Pressure does not have equal intensity in a flowing dynamic system
Pressure drops along the length of a hydraulic line in flowing systems

7. Flow and Pressure Flow, Q Pressure, P volume flow rate
amount of fluid moving through system per unit time
Pressure, P
force per unit area of fluid moving through a system

8. Mechanical Advantage Ideal Mechanical Advantage (IMA)
Assumes no frictional losses
Calculated as ratio of output force to input force

9. Ideal Mechanical Advantage

10. Mechanical Advantage Actual mechanical advantage (AMA)
always less than ideal
difficult to calculate

11. Application of Pascal’s Law in a Simple Hydrostatic System
In the schematic on the following slide:
How much force must you exert on piston A to lift a load on piston B of 500 lbs?

12. What is the ideal mechanical advantage of this system?

13. Problem Solving - Step 1 Known Unknown A = 500 in2 P=? F = 500 lb
Determine the pressure in the system using information about piston B
Known Unknown
A = 500 in P=?
F = 500 lb
Equation No algebra needed
Substitution & Solution

14. Step 2 Pressure units Known Unknown A = 1.0 in2 F=?
Use the pressure calculated in STEP 1 and information about piston A to calculate force:
Known Unknown
A = 1.0 in F=?

15. Step 2 = Algebraic solutions

16. Step 3 - Determine the IMA
Using information from STEPS 1 & 2
Known Unknown
F(input) = 1 lb IMA=?
F(output) = 500 lb
Equation No algebra needed

17. Step 4 - Substitution & Solution

18. A Hydraulic System

19. Tank/Reservoir
Storage device which is open and not pressurized
Filter

20. Pumps
Centrifugal pump (Vane Pump): no specific amount of fluid flow per rotation; flow depends on speed of blades
Positive displacement pump (Gear Pump): a specific amount of fluid passes through the pump for each rotation

21. Accumulators
Storage device which is closed and is under pressure

22. Valves
Check Valve
Directional Control

23. Use hydraulic power to move linearly
Linear Actuators
Use hydraulic power to move linearly
Single Acting Double Acting

24. Rotary Actuators
Use hydraulic power to rotate
Single-Vane Double-Vane

25. Applications Robotics Oil systems in vehicles (e.g. brakes) Presses
Heavy equipment
Wood splitter
Aircraft control systems

26. In-line Pressure Gauge Directional Control Valve
The Hydraulic Trainer
In-line Pressure Gauge
Supply line
Connections
Return line
Connections
Pressure Regulator
Return line
from reservoir
Flow Control Valve
Pressure line
Check Valve
Pump
Actuators
Motor
Inline-Tee
Directional Control Valve