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DIFFERENCE BETWEEN S.I AND C.I ENGINES

Criteria S.I. Engine (Petrol or Spark Ignition Engine) C.I. Engine (Diesel or Compression Ignition Engine) Working Cycle Works on Otto Cycle or Constant Volume Cycle. Works on Diesel Cycle. Mixture During Suction Stroke Takes a mixture of air and petrol during the suction stroke. Takes only air during the suction stroke. Fuel Used Uses petrol as fuel. Uses diesel as fuel. Compression Ratio Has a compression ratio that varies from 6 to 10. Has a compression ratio that varies from 16 to 20. Engine Weight and Cost S.I. engines are lighter and cheaper. C.I. engines are heavier and costlier. Initial Cost Initial cost is lower compared to C.I. engines. Initial cost is high due to high compression ratio. Starting Starting is easy. Starting is difficult, especially in cold conditions. ...

CLUTCH

CLUTCH - It is a mechanism which transfer rotary motion of one shaft to another shaft.

PARTS OF CLUTCH - 
• The driving unit
• The driven unit 
• The operating unit

FUNCTION OF CLUTCH
• To engage the engine power to Gear box
• To Disengage the engine power to Gear box.
• To help in shifting the Gear in Gear box.
• To provide a smooth and gradual operates to take up load without jerk.

TYPES OF CLUTCH - 



SINGLE PLATE CLUTCH:- It is a type of disc clutch. It uses a single disc called clutch plate.



CONSTRUCTION - 
•It consists of 3 main parts, Flywheel, clutch plate and pressure plate assembly. The flywheel is attached to engine shaft and actas driving member.
• The clutch plate is a steel disc. It is connected to splined hub through springs. The spleen shaft ,which is also a gear box shaft , slides in the hub. There is friction lining on both sides of the steel disc. The lining are either riveted or blinded on the steel disc.
• The pressure plate assembly consists of a pressure plate, coil springs or diaphragm springs , release lever and the cover.

WORKING - 
1.) When the clutch pedal is pressed, the release lever pedal pushes back the pressure plate. This the clutch plate is released. This is the Disengaged position of the clutch.
2.) When the pressure is removed from the clutch pedal, the spring again exerts the pressure on the pressure plate which in turn engage the clutch plate to the flywheel. 
The clutch plate is mounted on the splined shaft. So the splined shaft rotating which is connected to Gear box.

ADVANTAGES
• The pedal movement is less.
• Gear shifting is easy.

TYPES OF SINGLE PLATE CLUTCH:- 
• COIL SPRING
• DIAPHRAGM SPRING


MULTIPLATE CLUTCH - It consists of more than one clutch plate and driving plates. There are many clutch plate, the friction area is increased and hence the capacity of the clutch is increased.



CONSTRUCTION - There are two types of friction plates.

1.) One type have teeth or grooves on the outer surface. These grooves are fitted with flywheel and rotate with Flywheel.

2.) The other type have teeth or grooves in the inner side and these plates on spline shaft.
A pressure plate keeps the pressure on the friction plate with the help of springs.

WORKING - The outer teeth plates rotates with the flywheel. The inner plate having friction lining are fitted on the spline shaft.

• when the clutch pedal is pressed it pulls back the pressure plate and inner plate is released. Hence the clutch is Disengaged.
• when the pressure is removed from the clutche pedal, the spring pressure again come into play and clutch is engaged.

APPLICATION - It is used for heavy transport vehicles and Racing cars.

CONE CLUTCH - It consists frictional surfaces in the form of cones.
The male cone is mounted on splined clutch shafts, while the engine shaft consist of a female cone.


WORKING - When the clutch is engaged the frictional surfaces of male cone come in contact with the frictional surfaces of female cone due to action of spring force.
When the clutch pedal is pressed, the male cone slides against the spring force and the clutch gets Disengaged.

ADVANTAGES
• The normal force acting on the frictional surfaces is greater than the axial force as compare to single plate.

DISADVANTAGES
• Difficult to disengage is equal to axial force.
• A small amount of wear on the cone surfaces



SEMI CENTRIFUGAL CLUTCH - It is useful for High Torque.


CONSTRUCTION - There are three levers which act due to action of centrifugal force.
The flywheel, the clutch plate and pressure plate are arranged in the same manner as single plate clutch.
The levers are hinged on the pressure plate. The outer arm is called weight arm.
A weight is put on this arm.
There is an adjusting screw at the end of inner arm of the lever. This screw is used to adjust the pressure.

WORKING - When the clutch pedal is pressed, the clutch is Disengaged. After releasing the clutch pedal, the spring pressure plate and clutch plate is engaged.
The clutch starts working at the normal speed. When speed increases ,the centrifugal force moves the weight arm outward and inner arm start pressing the pressure plate. 
Due to this , the sufficient amount of is transmitted.



CENTRIFUGAL CLUTCH - It is an automatic clutch. In this no clutch pedal is required to control clutch operation. It is controlled by centrifugal forces 

CONSTRUCTION - In this bell crank lever is used with a mass M on the one side and other side in touch with an intermediate plate. There is spring between the intermediate plate and clutch plate.
The clutch plate has friction lining on it. No release lever is required as the clutch operation is automatic.

WORKING - 
• The bell crank lever rotates with Flywheel. When the speed of engine increases, the mass M falls outwards. This the lever presses the intermediate plate which pushes back the clutch plate with the help of spring. So the clutch plate is engaged with the flywheel.
• The pressure on the accelerator pedal is removed. When the engine speed is decreased and the mass M comes into its initial position. The pressure on the intermediate plate is removed and the clutch is in Disengaged position.


HYDRAULIC CLUTCH - It consists of a cylinder with piston, control valve, oil reservoir, pump and accumlator.
The piston is connected to the clutch with the help of linkage. The oil from reservoir is sent to accumlator tank with the help of pump. 
The accumlator tank is connected to the cylinder through control valve. The control valve is electrically controlled by switch in the gear lever.


WORKING - When the gear lever changes, the switch is operated which opens the control valve to entryof oil under pressure in cylinder.
Due to oil pressure, the piston moves and disengage the clutch.
When drivers leaves the gear lever, the switch is open which closes the control valve and clutch engaged.

















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