Introduction Muhajir Ab. Rahim School of Mechatronic Engineering

Refresh All industrial process are based upon the use of energy to do work, in just 4 types of systems 1.Mechanical 2.Electrical 3.Hydraulic 4.Pneumatic

The system evolution Old days (mechanical + air, water- natural resources) Modern days (mechanical +fluid power- electrical) Future ??? “new ways of applying and controlling machines (mechanical)”

Substance characteristics God has created (and still creating) three forms of substance 1.Solid 2.Liquid 3.Gas “Capable to change form”

Solid Maintains both its shape and volume -has specific shape and volume (size) Not affected by the shape of a container

Liquid Maintains its volume and takes the shape of its container- has specific volume

Gas Takes on both shape and volume of its container- no specific shape or volume

System characteristics Mechanical systems use solid materials such as metal, wood, or plastic formed into shafts, gears, pulleys, levers, rods, cams and other parts to transmit power. Hydraulic systems use a liquid, usually oil, which is pumped into hydraulic cylinders or hydraulic motors and made to do work. Pneumatic systems use a gas, usually air, which is pressurized and then directed into pneumatic cylinders and made to do work.

Which is the best system? Need to consider advantages and disadvantages (system comparisons)

What is fluid power? Fluid power is an applied science dealing with ways of using pressurized gas or liquid for doing work When a gas (usually air) is used- pneumatic system When a liquid (usually oil) is used- hydraulic system

Evolution of Fluid Power Fields of hydraulic or pneumatic are concerned with either transporting a fluid from one place to another or using fluid to do work. Eg, canals, tunnels for carrying water for drinking, irrigation, washing, floating vessels.. Water itself is needed, not its ability to transmit and use energy

The applications in which fluid was used to do work is such as windmills, sails, water wheel, hydroelectric power plant. It is called as open system because the air or water used was not confined, and it was weight or inertia that provided the force needed. Require large amounts of moving fluid at low pressures to accomplish their purpose.

The first closed fluid power system was invented by Joseph Bramah in the late 1700s. He assembled the first hydraulic jack or press as shown in figure below.

Lets check what we have learned…

Advantages 1.pose little or no safety hazard when not operating 2.easy to troubleshoot and repair 3.reliable to harsh environment 4.many ready standardized parts available in market Disadvantages 1.heavy and adds inertia 2.need periodic lubrication and protection 3.power transmission is limited 4.must be made strong Mechanical System

Hydraulic System Advantages 1.high force level 2.amount of force can be controlled with high degree precision 3.motion can be reversed/started/stopped quickly 4.can be made portable and stored Disadvantages 1.must be totally enclosed 2.entire system must be located closed to the point of actual usage 3.always have potential of fire hazard 4.limited speed of operation

Pneumatic System Advantages 1.air is readily available 2.low pressure loss in air lines (single compressor can supply pressurized air to several machines place a great distance away) 3.motion can be reversed very quickly 4.can stored energy for reserve or emergency use Disadvantages 1.lack of precision control 2.when air is compressed, heat is produced 3.air taken from atmosphere need to be filtered and dried 4.leaks can produce high pitch noise (hazardous to hearing)

Things to ponder… Why speed of operation is limited in hydraulic systems? If hydraulic oil flows to fast, it becomes turbulent and losses pressure. Why motion can be reversed very quickly in hydraulic and pneumatic systems? Little inertia