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. ...
CONSTANT MESH GEAR BOX -
• CONSTRUCTION:- The gear A mounted on the clutch shaft. The gear E , F , G and H are mounted on on the lay shaft. In this type , the gear E is always meshed with gear A. There is splined main shaft which is in alignment with gear box - shaft.
The gear B, C and D rotate freely on the main shaft. There is an idle shaft Gear I is mounted on it.
The gear B is always mesh with gear F and gear C is always mesh with gear G. The gear D is called reverse gear is always mesh with gear I which is mesh with gear H. There are two dog clutch D1 & D2 is mounted on main shaft which help in gear shifting.
WORKING:- In this the gear C is called a First gear , and Gear B is called a second gear and gear D is called a reverse gear.
FIRST GEAR - In this , the dog clutch D2 is slided on main shaft in such a way that the teeth of dog clutch are in contact with gear C. That means dog clutch D2 is engaged with gear C. The power of engine is transmitted through dog clutch D2 with gears A,E,G,C to main shaft.
SECOND GEAR -In this the dog Clutch D¹ is slided on main Shaft toword right such that the teeth of dog Clutch are - engaged with the teeth of gear B.
Top Gear - in this, the dog Clutch if slided toward left are such that its teeth are engaged with the teeth of gear A.
Reverse Gear - in this, the dog Clutch D2 is slided on the main shaft and it's teeth are engaged with of gear D. Then idler gear I reverse the direction of rotation of main shaft.