ROLE PARTS AND COMPONENTS PLAY IN PETROL AND DIESEL ENGINE

Engine design and components 

The engine is constructed from different parts. These parts are: bottom end, top end, front end, oil pan, valve cover, and front cover.

Bottom End (short block): The bottom end includes the cylinder block with all of its internal parts installed. The pistons, rods, crankshaft, and bearing would be in the block. The term short block is often used to mean the same thing as bottom end.

Long block: is a technician term that refers to the short block with just the heads installed. Parts like valve covers, front cover, flywheel, mounts, etc. are not included in the long block

Bare block: is a cylinder block with all parts removed. There would not be pistons, rods, a crankshaft, nor other parts in the block. 

Bottom (Lower) End Construction 

? Cylinder block deck: is a flat machined surface for the cylinder head. Bolt holes are drilled and tapped in the deck for head bolts. Coolant and oil passages allow fluids through the block, head gasket, and cylinder heads.

? Cylinders (cylinder walls): are large holes machined in the cylinder block for the pistons. An integral cylinder is part of the block.

? Cylinder block sleeves (liners): is a separate part pressed into the block. There are two basic types of cylinder sleeves: dry sleeves and wet sleeves.

? Cylinder bores: There are several bores in the block, lifter bores, cam bores, main bore.

? Main caps: they are blot to the bottom of the cylinder block and form one-half of the main bore. Large main cap bolts screw into holes in the block to secure the caps to the block

? Main bearings: snap-fit into the cylinder block and main caps to provide an operating surface for the crankshaft main journals.

? Crankshaft: It converts the reciprocating of the pistons into a rotating motion. The crankshaft fits into the main bore of the block The crankshaft has a crankshaft oil passages, counterweights, crankshaft flange with the pilot bearing in the center to support the manual transmission input shaft, and the crankshaft oil seals.

? Crank main journals: are precision machined and polished surfaces that ride on the main bearings.

? Crank rod journals: also terms crankpins are also machined and polished surfaces, but they are for the connecting rod bearings.

? Flywheel: is a large steel disc mounted on the rear flange of the crankshaft. The flywheel has a large ring gear that allows engine starting.

? Connecting rod: fastens the piston to the crankshaft.

? Connecting rod cap: bolts to the bottom of the connecting rod body. It can be removed to for disassembly of the engine.

? Connecting rod bearings: rid on the crankshaft rod journal.

? Piston pin: allows the piston to swing on the connecting rod. The pin fits through the hole in the piston and the connecting rod small end.

? Pistons: transfers the pressure f the combustion to the connecting rod and crankshaft. It must hold the piston rings and piston pin while operating in the cylinder.

? Piston rings: Automotive pistons normally use three rings- two compression rings and one oil ring.

? Balancer shafts: are used in some engines to reduce vibration. These counterweighted shafts are generally mounted in the left and right side of the engine block and are driven by a belt or chain. 

Top (Upper) End Construction

 * The cylinder head: bolts to the deck of the block and covers the top of the cylinders. A head gasket seals the block and head surfaces to prevent oil, coolant, and pressure leakage.

* Bare cylinder head: is a head casting, with all of its parts (valves, keepers, retainers, springs, seals, and rocker arms) removed. The cylinder head consists of combustion chambers, intakes ports, exhaust ports, oil passages, water jackets, intake deck, exhaust deck, and dowel holes.

* Valve guides: are small holes machined through the top of the head, do into the intake and exhaust ports. The two basic types of valve guides are the integral and pressed-in.

* Valve seats: are round, machined surfaces in the port openings to the combustion chambers. The valve seats can be part of the head or a separated pressed-in component.

* Valves: open and close to control flow in and out of the combustion chamber. 

* Valve seals: prevent oil from entering the cylinder head ports through the valve guides.

* Valve spring assembly: is used to close the valve. It basically consists of a valve spring, retainer, and two keepers.

* Camshaft: opens the engine valves at the right time during each stroke.

* Camshaft gear: a camshaft sometimes has a drive gear for operating the distributor and oil pump.

* Camshaft eccentric: An eccentric (oval) may be machined on the camshaft for a mechanical (engine driven) fuel pump.

* Camshaft bearings: are usually one-piece inserts pressed into the block of cylinder head.

* Valve lifters: also called tappets, ride on the cam lobes and transfer motion to the rest of the valve train.

* Push rods: transfer motion between the lifters and the rocker arms. They are needed when the camshaft is located in the cylinder block

* Rocker arms: can be used to transfer motion from the push rods to the valves. They can be used in both OHC and OHV engines. In any engine, the rockers mount on top of the cylinder head by various methods; rocker shaft, rocker stud, or rocker pedestal. There are two types of rocker arms; adjustable rocker arms, and nonadjustable rocker arms. Adjustable rocker arms provide a means of changing valve train clearance. Nonadjustable rocker arms provide no means of changing valve clearance. They are only used with some hydraulic lifters.

* Solenoid-operated rockers: are used on variable displacement (size) engines. The solenoids can be turned on or off to deactivate or activate some of the engine valves.

* Variable Valve Timing: alter valve timing as engine speed changes. This is done to optimize engine power and efficiency at all operating speeds. 

Front End Construction 

Camshaft drive mechanism also called timing mechanism, must turn the camshaft and keep it in time with the engine crankshaft and pistons. Sometimes, it must also power other units (balancer shaft, oil pump, distributor, etc.) There are three basic types of camshaft drives: gear drive, chain drive, and belt drive.

? Gear drive: Timing gears are two helical gears on the front of engine that operate the engine camshaft.

? Timing chain and two sprockets: the timing chain transfers power from the crank sprockets to the cam sprockets. A crankshaft key is used to lock the crankshaft sprocket to the shaft. A camshaft key or dowel is used to secure the cam shaft sprocket on the cam, and assures that the sprocket does not spin on the camshaft and go out of time. A chain tensioner can be used to take up excess slack as the chain and sprockets wear. A chain guide may be needed to prevent chain slap. Auxiliary chain and sprocketsmay be used to drive the engine oil pump, balancer shafts, and other units on the engine. Oil slinger helps spray oil on the timing chain to prevent wear. Engine front cover, also called timing chain or timing gear cover, is a metal housing that bolts on the front of the engine. It encloses the timing chain or gears to keep oil from spraying out. The cover holds the crankshaft oil seal.

? Timing belt: Teeth axe formed in the inside of the belt. They mesh with the teeth on the outside of the crank and cam sprockets. A belt sprocket normally has square teeth. Timing belt tensioner is a wheel that keeps the timing belt tight on its sprockets. Timing belt sensors detects excessive tensioner extension and timing belt wear and stretch. When the sensor detects belt stretch, an indicator of possible belt failure, it signals the ECU. The ECU can then illuminate a dash light to warn the driver of the problem. An auxiliary belt sprocket, also termed intermediate sprocket, can be used to operate the oil pump, water pump, distributor, etc. The timing belt simply extends around this extra sprocket. A timing belt cover is simply a sheet of metal or plastic shroud around the cam drive belt.

* Crankshaft pulleys: are needed to operate the alternator, power steering pump, air conditioning compressor, air injection pump, and other devices.

* Engine balance shafts: are geared to the crankshaft or camshaft. The balance shaft has bob weights that spin in the opposite direction of crankshaft rotation. This cancels out torsional vibrations created by the crankshaft, providing a smoother engine idle.

* Intake manifolds: is a metal casting or plastic part casting that bolts over and covers intake ports on the cylinder head.

Exhaust manifold bolts to the cylinder head, over the exhaust ports. Valve cover also called rocker cover or cam cover on OHC engines, is a thin housing over the top of the cylinder head. It simply keeps valve train oil spray from leaking out if the engine. The cover is sealed by a gasket or sealant.

Engine gaskets prevent pressure, oil, coolant, and air leakage between engine components. They are; cylinder head gasket, valve cover gasket, oil pan gasket, front cover gasket, thermostat housing gaskets, intake and exhaust manifold gaskets, etc.

Oil pan and sump 

The oil pan, normally made of thin sheet of metal or aluminum, bolts to the bottom of the engine block. It holds an extra supply of oil for the lubrication system. The oil pan is fitted with screw-in drain plug for oil changes. The sump is the lowest area in the oil pan where oil collects. 

Single- and multi- cylinder engines 

Power/weight ratio:

The engine power varies as the square of the bore (that is, with the piston area) but the mass varies as the cube of the bore (that is, with the volume of material used). Increasing power by using a large cylinder therefore results in a low power/weight ratio, whereas increasing the number of cylinders maintains power and weight in the same proportions. 

Firing interval and torque fluctuation:

Since all the cylinders must fire in two revolutions of the four-stroke crankshaft, the firing intervals is 7200 divided by the number of cylinders. The effective power stroke occupies about 1350. With a. single cylinder the mass of a large flywheel is required to absorb torque fluctuations and provide energy for the crankshaft. As the number of cylinders increases, torque is smoother and less weight flywheel is needed, aiding acceleration. 

Balance and inertia loads:

The single-cylinder unit can only be imperfectly balanced and vibration will occur at certain engine speeds. Four-cylinder in-line units have small secondary out-of-balance forces, while horizontally opposed; six and eight-cylinder units can have entirely satisfactory balance. The reduced reciprocating mass of the multi-cylinder engine permits higher crankshaft speeds without inertia force problems. 

Diesel Engine Main Parts - Rudolf Diesel, maybe that name sounds strange to ours. But he is the one behind the invention of diesel engines. The diesel engine is an internal combustion engine that utilizes diesel fuel to perform the combustion process. The working principle of the diesel engine is almost the same as gasoline engine, but there is little difference in step effort this machine.

How about the components ? is there any different ? of course there is a difference between diesel and gasoline engines. This difference arises because the diesel engine is have harder duty cycle, so the material used must also be adjusted. But in general 4 stroke diesel engine components are not nearly the same as 4-stroke gasoline engine. If we discuss, there will be hundreds of components on a 4 stroke diesel engine. These components certainly have their own duties and functions.

For now we will only discuss the main parts of 4 stroke diesel engine and their functions. The main component of a diesel engine is all the components that are directly related to the 4 stroke diesel fuel cycle. While other components that are not directly related like altenator or starter motor we will discuss in another article. So, what is the name of the main components of diesel engine 4 stroke? refer to the article below

1.Cylinder Block Asyembly

Cylinder block is the main component of internal combustion engine both 2 stroke and 4 stroke. This component becomes a primary component to place various engine compartments that support the working process of the machine. As we can see in the picture above, the shape of the cylinder block of each machine is generally the same but the details will be different. That's because the details of the cylinder block are adjusted with all components that will stick to this block.

Cylinder block made of cast iron which has a high degree of precision. Generally on a block cylinder has several components

• Cylinder / main linner. This component will serve as a place up and down the piston.The components is made of iron and aluminum alloy located inside of engine block using press methode, so it will be difficult to detach.
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• Water jacket. Water jacket is a cooling water sheath located inside the engine block. The goal for the engine cooling process takes place. hole-shaped water jacket inside the cylinder block that surrounds the linner.
• Oil feed lines. The oil hole on the cylinder block serves to create the engine oil line from the cylinder head to the crankcase. This hole will support the engine oil circulation process to all diesel engine parts.

Cylinder Head Asyembly

The second component unit is located on the top of the engine. Similar to cylinder block, this component is also made of cast material. Currently aluminum head cylinder seems to be an option, because it is lighter and stronger. This unit consists of valve & spring, camshaft, rocker arm, and combustion chamber.

• Valve & spring. This component becomes the door that will open and close the intake and exhaust channels on the combustion room. While spring will keep the valve close.

The valve which allows mixture into the cylinder is the inlet valve; the one through which the spent gases escape is the exhaust valve. They are designed to open and close at precise moments, to allow the engine to run efficiently at all speeds.

The operation is controlled by pear-shaped lobes, called cams, on a rotating shaft, the camshaft, driven by a chain, a belt, or a set of gears from the crankshaft.

Where the camshaft is mounted in the engine block, small metal cylinders tappets sit in channels above each cam, and from the tappets metal pushrod extend up into the cylinder head. The top of each pushrod meets a rocker arm which bears against the stem of a valve, which is held in a raised (closed) position by a strong coiled spring the valve spring.

As the pushrod rises on the cam it pivots the rocker arm, which pushes the valve down (open) against the pressure of its spring. As the cam lobe rotates further, the valve spring acts to close the valve. This is called an overhead-valve (OHV) system.

Some engines have no pushrods; the valves are operated more directly by single or double camshafts in the cylinder head itself the overhead-cam system.

As there are fewer moving parts between the camshaft and the valve, the overhead-cam (OHC) method is more efficient and produces more power for a given engine capacity than an engine with pushrods, because it can operate at higher speeds. With either system, there must be some free play in the operating gear, so that the valve can still close completely when parts have expanded through heat.

A pre-set gap tappet clearance is essential between the valve stem and the rocker arm or cam, to allow for expansion. Tappet clearances vary widely on different cars, and faulty adjustment can have serious effects.

If the gap is too large, the valves open late and close early, reducing power and increasing engine noise.

Too small a clearance prevents the valves from closing properly, with a consequent loss of compression.

Some engines have self-adjusting tappets, which are hydraulically operated by the engine oil pressure.

Camshaft with pushrods

Camshaft with pushrods

When the camshaft is mounted in the engine block, long pushrods operate the rocker arms which in turn open the valves. This overhead-valve (OHV) system is less efficient than an overhead camshaft because the number of moving parts limits the speed at which the engine can run safely.

The overhead valve system (OHV) system, operated by pushrods, has the crankshaft adjacent and parallel to the crankshaft in the cylinder block.

As the crankshaft rotates, each valve is opened by means of a tappet, pushrod and rocker arm. The valve is closed by spring pressure.

The camshaft drive-chain sprocket has twice as many teeth as the crankshaft sprocket, so that the camshaft rotates at half engine speed.

Engine with overhead camshaft

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Finger-operated OHC

In some designs the cams act directly on short levers, called fingers.

An overhead-cam (OHC) engine needs fewer parts to operate the valves. The cams act directly on bucket tappets or on short levers - known as fingers - which in turn act directly on the valve stems.

The system dispenses with the extra weight and mechanical complexity of pushrods and rocker arms.

A long chain is frequently used to drive the camshaft from a sprocket on the crankshaft, but such a long chain tends to 'whip'. The problem is overcome in some designs by fitting intermediate sprockets and two shorter drive chains, kept under tension.

• Another method uses a non-stretch oil-resistant, toothed rubber drive belt which engages with toothed sprockets on the camshaft and crankshaft.
• Camshaft. Camshaft is a component that have several cam, this cam have a fungtion to press the valve. Once valve pressed, the chanel of intake or exhaust port will open.
• Rocker arm. This component will press the valve when the nok touches the top of the rocker arm. So the in / ex channel can open. Generally rocker arm has valve gap adjustment system, either manual or automatic (Hydrolic Lash Adjuster).
• Combustion chamber. The combustion chamber is a small space used for combustion. the result is a blast of fire used to push the piston down. Usually this combustion chamber is found on indirect injection diesel engine.

Piston and connecting rod

Piston have a function to adjust the volume inside the cylinder. why the volume of the cylinder needs to be regulated? this is so that the working process of the 4 stroke engine can take place. In this case when the piston moves down the volume of the cylinder will enlarge, while when the piston moves up the volume of the cylinder will shrink. While connecting rod serves to continue the motion up and down the piston to flywheel. In general there are three core parts on the piston namely;

• Ring compression. This rings are elastic in function to prevent the occurrence of air leaks during the compression stroke. The way this ring works is to close the gap between the piston wall and the main linner.
• Oil ring. Ring printed under the compression ring serves to prevent engine oil from entering the combustion chamber.
• Pin pistons. A pin located inside the piston to connect the piston with the connecting rod. This pin is tubular, when connected to the small end it will function like a hinge.

Crankshaft

Crankshaft is a component made of cast iron which is used to turn the piston up and down motion into a rotary movement. The working principle of crankshaft is similar when we using a bicycle. Because it is related to the pressure of the piston, the crankshaft should not be supple or fracture when it gets pressure from the piston. For this component is made of special iron alloy that has high strength and anti-fastness. Some parts on the crankshaft are;

Crank pin. Crank pin is a pin that will connect to the big end on the connecting rod.

Crank journal. While the crank journal is a pin that serves as a shaft on the crankshaft in order to spin. Crank journaling will be attached to the cylinder block.

Weight balance. This component is located opposite the crank pin, its function as a counterweight as well as to drain the oil to the entire inside of the machine.

Oil Pan

Oil pan (Carter) is a special tub that serves to accommodate engine oil. Although only served as a container of engine oil, this component also can not be made carelessly. Generally these components are made of thin iron like zinc, but some cars have combined with thicker materials.

Timming Chain Asyembly

The timing chain is included in the valve mechanism system, its function to connect the crankshaft and camshaft rotation with a certain angle. The component of this chain is located on the front of the engine. This chain will connect the sprocket gear from the crankshaft with the sprocket gear of the camshaft.

Fly Wheel

Flywheel initially serves to balance the engine speed. This component is made of solid iron that can store torque, that's why this component can balancing the engine speed.

In addition, flywheel also serves to power the engine, this can be seen from the outside of the flywheel that has many gear. The gear will be connected with starter motor pinion to start the engine.

Balance Shaft

Balance shaft – a counterweighted engine shaft that offsets unwanted crankshaft vibrations by rotating in the opposite direction. In our Balance Shafts & Components section, we also offer related hardware such as shaft seals, individual counterweights, replacement sleeves, and more.

Bearing

Bearing – A curved metal piece that allows motion between components with minimum wear and friction. A bearing that surrounds a shaft may be circular in shape (camshaft bearing), or semi-circular (connecting rods, crankshaft), in which case it is also known as a bearing shell. Also see Main bearings and Rod bearings. In our section for Bearings & Components, we’ve got camshaft bearings, crankshaft main bearings, connecting rod bearings, balance shaft bearings, auxiliary shaft bearings, and much more.

Bearing Cap

Bearing cap – A retainer, held in place by nuts and bolts, which secures bearing shells in place.

Camshaft

Camshaft – A shaft in the engine connected to the crankshaft via gears, belts, or a chain, which contains a series of cams to open and close intake and exhaust valves. We also stock related camshaft hardware such as sleeves, bolt lock plates, end caps, dowel pins, o-rings, seals, oil line fittings, oiler control valves, retainer clips, thrust buttons & plates, and much more.