VISHWESHWARAYYA ABHIYANTRIKI PADAVIKA MAHAVIDYALAYA, ALMALA

1. VISHWESHWARAYYA ABHIYANTRIKI PADAVIKA MAHAVIDYALAYA, ALMALA

2. MECHANICAL ENGINEERING A SEMINAR ON PISTON AND GEAR

3. CONTENTS:- GEAR:- 1) Introduction of gear 2)History of gear 3)Importance of gear 4)classification of gear 5)spur gear 6) helical gear 7)bevel gear 8)worm gear 9)racks(straight gear) 10)Application of gear PISTON:- 1)introduction of piston 2)history of piston 3)Importance of piston 4)construction of piston 5)construction of piston 6)Advantages 7)

4. GEARS INTRODUCTION:- • Gears are a means of changing the rate of rotation of a machinery shaft. They can also change the direction of the axis of rotation and can change rotary motion to linear motion. • Unfortunately, mechanical engineers sometimes shy away from the use of gears and rely on the advent of electronic controls and the availability of toothed belts, since robust gears for high-speed and/or high-power machinery are often very complex to design. However, for dedicated, high-speed machinery such as an automobile transmission, gears are the optimal medium for low energy loss, high accuracy and low play. • Gears are of several categories, and can be combined in a multitude of ways, some of which are illustrated in the following figures. GEARS: • A toothed wheel that works with others to alter the relation between the speed of a driving mechanism (such as the engine of a vehicle) and the speed of the driven parts (the wheels).

5. HISTORY OF GEAR:-

6. IMPORTANCE OF GEAR:- • Below is the importance of gears. • Theteeth of the gears help in preventing slipping. Slipping is when the transmission lags behind and at times when it occurs it’s usually very difficult to diagnose the problem.  • Another importance of gears is that, they add a mechanical advantage to the type of machine you are using. By this we mean that, when two gears with a number of teeth that is not equal are put together, that is when a mechanical advantage is produced. • Atlanta Drive Systems is one of the leading manufacturer industries in the world in the supply of helical gears. The gears made here are of a great quality and they stay for a long time without rusting. They supply all over the Tooth versions that a consumer wants from the cheapest to the most expensive of them all.

7. CLASSIFICATION OF GEAR Parallel Shaft Intersecting shaft Non parallel shaft Spur gear Helical gear Crossed helical gear Worm gear Hypoid gear Bevel gear Angular gear Crown gear Spiral gear C oni flex gear

8. Gears What we need to Know about them. Type of gears Terminologies or nomenclatures Forces transmitted Design of a gear box

9. Spur Gears Are used in transmitting torque between parallel shafts

10. Helical Gears Are used in transmitting torques between parallel or non parallel shafts, they are not as noisy as spur gears

11. Bevel Gears • Are used to transmit rotary motion between intersecting shafts Teeth are formed on conical surfaces, the teeth could be straight or spiral.

12. Worm Gears Are used for transmitting motion between non parallel and non transmitting shafts, Depending on the number of teeth engaged called single or double. Worm gear mostly used when speed ratio is quiet high, 3 or more

13. Gear Applications: • More so than most mechanical components, the performance and life of gears are directly effected by their surface characteristics. Most gear failures are closely linked to excessive stresses, inadequate lubrication or excessive pitch line velocities. • Gear systems offer a significant opportunity for improved performance through the application of Timken's Engineered Surfaces technology These processes are perfectly suited to gears, enabling equipment designers to upgrade the performance, capacity or life of gearboxes. • Because modification of the component surface creates only negligible dimensional changes, designers can realize these benefits with no need to redesign the entire system. 

14. PISTONS

15. INTRODUCTION:- • General: Piston rings in and compressors have three main functions: to seal the working chamber  • from the crankcase, to assist in the flow of heal from piston to cylinder wall and to control oil  • consumption.In order to achieve efficient sealing the piston ring should make a good fit with both the  • cylinder wall and either the top or bottom of the piston groove. The radial fit is achieved by the inherent  • Piston rings are also used in increasing numbers as metallic seals for rotating shafts PISTON: • A disc or short cylinder fitting closely within a tube in which it moves up and down against a liquid or gas, used in an internal-combustion engine to derive motion, or in a pump to impart motion. • A valve in a brass musical instrument in the form of a piston, depressed to alter the pitch of a note.

16. HISTORY OF PISTON:- • The development of the piston engine marked the beginning of the industrialization period in Europe, setting the stage for the mass production of steam engines, automobiles and airplanes. Piston engines provided lots of power without weighing down the machine, allowing planes, trains and cars to accelerate and reach speeds that no other mode of transport had ever achieved.

17. Piston Design Considerations • Pistons must: • Contain cylinder pressure • Transmit the pressure created by combustion to force on the connecting rod • Provide a place for oil control and compression rings to be located 1. The piston must have the strength to resist the impulse and inertia forces.2. Ability to disperse the heat of combustion and avoid thermal distortion.3. Sealing the gas and oil4. Sufficient bearing area to work for large number of reciprocating cyles5. Minimum weight6. Smooth noiseless operation7. Provide adequate support for piston pin

18. Piston Design Considerations • Pistons must: • Be rigid enough to not deform under the tremendous pressures and forces encountered • Be ductile enough to absorb pressure peaks and not shatter • Retain the proper shape under the extreme temperatures encountered

19. Piston Construction • Materials • Cast iron (used in very old engines) • Cast aluminum (most common) • Forged aluminum • Hypereutectic alloys (high silicon content aluminum) • Carbon Graphite (being tested)

20. Piston Construction • Piston head • Round • Approx. .040 undersized • Ring grooves • Ring lands • Drain holes and slots • Wrist pin boss

21. Pistons may have a dished, flat or domed design Piston Head Design

22. Advantages:- Potential advantages of the free-piston concept include Simple design with few moving parts, giving a compact engine with low maintenance costs and reduced frictional losses. The operational flexibility through the variable compression ratio allows operation optimization for all operating conditions and multi-fuel operation. The free-piston engine is further well suited for homogeneous charge compression ignition (HCCI) operation.High piston speed around top dead center(TDC) and a fast power stroke expansion enhances fuel-air mixing and reduces the time available for heat transfer losses and the formation of temperature-dependent emissions such as nitrogen oxides

23. thanks you !