Chapter 8: Hydraulic Systems Overview and Applications | Môn Công nghệ cảm biến - Đại học Sư phạm Kỹ thuật Thành phố Hồ Chí Minh

lOMoAR cPSD| 58583460 H
o C h i M i n h C i t y U n i v e r s i t y o f T e c h n i c a l E d u c a t i on
Pneumatic & Hydraulic Technology Chapter 8: Hydraulic Introduction Instructor: Phan Thi Thu Thuy lOMoAR cPSD| 58583460 Higher
Engineering Education Alliance Program lOMoAR cPSD| 58583460 lOMoAR cPSD| 58583460 Objectives
1. Be able to list at least 5 applications of hydraulic
system within 5 minutes after attending the lecture.
2. Be able to caculate 100% correctly the work done
and power of hydraulic system in an appointed
particular case after attending the lecture.
3. Be able to demonstrate the working principle of 3
main types of hydraulic pumps and cylinders with 100% correctly. Definition lOMoAR cPSD| 58583460
❖ The main function of a hydraulic fluid in a hydraulic system
is to transfer forces and movements.
❖ The term fluid includes liquid, steam or gases. Air is also a
fluid when considered as a mixture of gases. As fluid power
is concerned with the mechanical characteristics of fluids,
we use the term: ✓Hydro-mechanics: dealing with liquids
✓Aeromechanics: dealing with air.
❖ Further tasks and characteristics are required of the
hydraulic fluid, due to the diverse range of applications and
installations of hydraulic drives. lOMoAR cPSD| 58583460 Types of energy transfer lOMoAR cPSD| 58583460 Fluid requirements
❖ Lubrication and anti-wear characteristics
❖ The fluid must be capable of covering all moving parts with a tenacious lubricating film.
❖ The lubricating film may be destroyed, as a result of high pressures,
insufficient oil delivery, low viscosity and either slow or very fast
sliding movements. This would result in WEAR due to fretting
(standard clearance tolerance e.g. in directional valves is 8 to 10 11m).
❖ Wear due to abrasion occurs between parts, which slide across each
other, when contaminated (with solid particles e.g. metal dust, slag,
sand, etc.) unfiltered or insufficiently filtered fluids are used. The
foreign particles carried along may also cause abrasion in the
devices at high fluid velocities. lOMoAR cPSD| 58583460 Viscosity
❖ Viscosity is the name given to the characteristic of a fluid,
where a fluid exerts a resistance to the laminar
movement of two neighbouring fluid layers against each other
❖ The viscosity of fluids changes as pressure increases.
This characteristic must be taken into account when
planning hydraulic systems which use pressures of more
than 200 bar. By approximately 400 bar, the viscosity has already been doubled. lOMoAR cPSD| 58583460
Viscosity / temperature diagram lOMoAR cPSD| 58583460
Fluid tmperature and viscosity ranges of required hydraulic components Example 1 Example 2
❖ Gear pump G4 (Fixed ❖ Vane pump V2 (Fixed
displacement pump) displacement pump)
✓ Fluid temperature range ❖ Fluid temperature range -15 to 800C -10 to 700C
✓ Viscosity range 10 to ❖ Viscosity range 16 to 300 mm2/s 160 mm2/s
From the component catalogue "RE 00 101" from Mannesmann Rexroth9 lOMoAR cPSD| 58583460 Range of applications lOMoAR cPSD| 58583460 Applications ❖Hydraulic truck cranes can lift thousands of pounds using the simple concept of transmitting forces from point to point through a fluid. lOMoAR cPSD| 58583460
Application: Lathe, Bending machine Tube bending lOMoAR cPSD| 58583460 Applications Application: Bulldozer lOMoAR cPSD| 58583460 Applications Video1 lOMoAR cPSD| 58583460 Application: Bulldozer
❖ Excavation machine for pushing materials; it is made up
of a crawler tractor, a blade and often a ripper.
http://visual.merriam-webster.com/transport-machinery/heavy-machinery/bulldozer. 15 php lOMoAR cPSD| 58583460 Application: wheel loader
❖ Excavation machine made up of a wheel tractor, a
backhoe and a front-end loader
http://visual.merriam-webster.com/transport-machinery/heavy-machinery/wheel-loader. 16 php lOMoAR cPSD| 58583460 Application: Hydraulic Shovel
❖ Machine made up of a pivot cab with a bucket attached for
moving various types of material.
http://visual.merriam-webster.com/transport-machinery/heavy-machinery/hydraulic-shovel.php 17 lOMoAR cPSD| 58583460 Application: Scraper
❖ Machine that uses a blade to scrape the ground or
roadbed and store the rubble in a bowl for disposal.
http://visual.merriam-webster.com/transport-machinery/heavy-machinery/scraper. 18 php lOMoAR cPSD| 58583460 Application: Dump truck
❖Truck equipped with a dump body; it is used for bulk transport.
http://visual.merriam-webster.com/transport-machinery/heavy-machinery/dump-truck. 19 php