1. CYLINDER BLOCK- The engine block is the linchpin of vehicles which run on internal combustion, providing the powerhouse for the vehicle. EX: A General Motors in-line, 6-cylinder block- the entire unit is a one-piece casting of alloy cast iron. Transverse members provide rigidity and strength, ensuring alignment of the bores and bearings under all loads. Function- In the bore of cylinder the fresh charge of air-fuel mixture is ignited, compressed by piston and expanded to give power to piston. 2.
CYLINDER HEAD- It closes in the top of the cylinder, forming the combustion chamber. The head can also be a place to mount the valves, spark plugs, and fuel injectors. EX: Overhead Cam- valve train configurations place the engine camshaft within the cylinder heads, above the combustion chambers, and drive the valves or lifters in a more direct manner compared to overhead valves (OHV) and pushrods. Function-It carries inlet and exhaust valve. Fresh charge is admitted through inlet valve and burnt gases are exhausted from exhaust valve.
In case of petrol engine, a spark plug and in case of diesel engine, an injector is also mounted on cylinder head. 3. CONNECTING ROD- The load on the piston due to combustion of fuel in the combustion chamber is transmitted to crankshaft through the connecting rod. EX: Compound Rods- Many-cylinder multi-bank engines such as a V12 layout have little space available for many connecting rod journals on a limited length of crankshaft. Function-It changes the reciprocating motion of piston into rotary motion at crankshaft.
This way connecting rod transmits the power produced at piston to crankshaft. 4. SPARK PLUG- A device inserted in the head of an internal-combustion engine cylinder that ignites the fuel mixture by means of an electric spark. EX: Surface-discharge spark plug- A piston engine has a part of the combustion chamber that is always out of reach of the piston; and this zone is where the conventional spark plug is located. Function- This device is used in petrol engine only and ignite the charge of fuel for combustion. . CARBURETTOR- is a device that blends air and fuel for an internal combustion engine. EX: Accelerator pump- Liquid gasoline, being denser than air, is slower than air to react to a force applied to it. When the throttle is rapidly opened, airflow through the carburetor increases immediately, faster than the fuel flow rate can increase. Function-It converts petrol in fine spray and mixes with air in proper ratio as per requirement of the engine.