1. Hydraulic Power © 2012 Project Lead The Way, Inc.Principles of Engineering

2. Hydraulic Power Hydraulic power Hydraulics vs. pneumatics Early hydraulic uses Hydrodynamic systems Hydrostatic systems Liquid flow Mechanical advantage Bernoulli's principle Viscosity Common hydraulic system components Emerging hydraulic application example

3. Hydraulic Power Hydraulics –The use of a liquid flowing under pressure to transmit power from one location to another Liquid in a hydraulic system behaves like a solid since it compresses very little

4. Hydraulic Power

5. Hydraulics vs. Pneumatics Hydraulic Systems Use a relatively incompressible liquid Have a slower, smoother motion Are generally more precise Lubricate naturally Are not as clean as pneumatics when leakage occurs Often operate at pressures of 500–5000 psi Generally produce more power

6. Early Hydraulic Uses Water Wheels Create rotational motion Descriptions exist as early as 1st century BC Several examples in ancient China Grist mill is pictured

7. Early Hydraulic Uses Roman Aqueducts Delivered water to buildings, agricultural fields, and fountains Used gravity to create flow Fountains were decorative and used by people to collect water for practical use

8. Hydrodynamic Systems Fluid is in motion Force and energy are transmitted by flow Water Turbine Propeller

9. National Fluid Power Association & Fluid Power Distributors Association Hydrostatic Systems Fluid does not flow quickly or continuously Fluid is pressurized Force and energy transmitted by pressure Most common in industrial settings

10. Hydrostatic Systems Click the arrows to activate the hydraulic press. Pascal’s Law Pressure exerted by a confined fluid acts undiminished equally in all directions

11. Liquid Flow Flow Rate The volume of fluid that moves through a system in a given period of time Flow Velocity The distance the fluid travels through a system in a given period of time SymbolDefinitionExample Units Q Flow Rategpm or gal/min (gallons per minute) in. 3 / min v Flow Velocityfps or ft/s (feet per second) in. / min A Areain. 2

12. Liquid Flow Example Float Q = 15 gal/min d = 2 in. v = ? Convert 15 gal/min to in. 3 /min 1 gal = 231 in. 3 Reprinted with permission from Introduction to Fluid Power, by James L. Johnson. Copyright © 2002 Thomson Delmar Learning. A flow meter attached to the main line in a hydraulic system measures the flow rate at 15 gpm. The line has an inside diameter of 2 in. What is the flow velocity in the meter?

13. Liquid Flow Example A flow meter attached to the main line in a hydraulic system measures the flow rate at 15 gpm. The line has an inside diameter of 2 in. What is the flow velocity in the meter? Q = 3465 in. 3 /mind = 2 in.v = ?

14. Mechanical Advantage National Fluid Power Association & Fluid Power Distributors Association

15. Mechanical Advantage Example A force of 100. lbf is applied to the input cylinder of the hydraulic press seen below. What is the pressure in the system? How much force can the output cylinder lift? What is the mechanical advantage of the system? d in = 4.0 in. d out = 12.0 in. F in = 100. lbf F in = 100. lbf F out = ? d in = 4.0 in. d out = 12.0 in. A in = ? A out = ? p = ? MA = ?

16. Mechanical Advantage Example F in =100. lb F out =? R in =2.0 in. R out =6.00 in. A in =? A out =? p=? MA=? Find the area of each cylinder.

17. F in =100. lb F out =? R in =2.0 in. R out =6.00 in. A in =12.57 in. 2 A out =113.10 in. 2 p=? MA=? Find the pressure in the system. Mechanical Advantage Example

18. F in =100. lb F out =? R in =2.0 in. R out =6.00 in. A in =12.57 in. 2 A out =113.10 in. 2 p=7.955 lb/in. 2 MA=? Find the force that the output cylinder can lift. Mechanical Advantage Example

19. F in =100. lb F out =900.28 lb R in =2.0 in. R out =6.00 in. A in =12.57 in. 2 A out =113.10 in. 2 p=7.96 lb/in. 2 MA=? Find the mechanical advantage of the system. Mechanical Advantage Example

20. Conservation of Energy: An increase in velocity results in a decrease in pressure. Likewise, a decrease in velocity results in an increase in pressure. Bernoulli’s Principle

21. Viscosity The measure of a fluid’s thickness or resistance to flow Crucial for lubricating a system Measured in slugs/sec-ft (US) or centistokes (metric) –Hydraulic oil is usually around 1.4 slugs/sec-ft Decreases as temperature increases

22. Common Hydraulic System Components National Fluid Power Association & Fluid Power Distributors Association Cylinder Transmission Lines Directional Control Valve Pump Reservoir Filter

23. Click the lever on the valve to extend and retract the cylinder. Reservoir Pump Cylinder Valve Common Hydraulic System Components

24. Image Resources Johnson, J.L. (2002). Introduction to fluid power. United States: Thomson Learning, Inc. Microsoft, Inc. (2008). Clip Art. Retrieved January 10, 2008, from http://office.microsoft.com/en-us/clipart/default.aspx http://office.microsoft.com/en-us/clipart/default.aspx National Fluid Power Association. (2008). What is fluid power. Retrieved February 15, 2008, from http://www.nfpa.com/OurIndustry/OurInd_AboutFP_WhatIsFluidPower.asp National Fluid Power Association & Fluid Power Distributors Association. (n.d.). Fluid power: The active partner in motion control technology. [Brochure]. Milwaukee, WI: Author.