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Suspension System

Suspension is the system of tires, tire air, springs, shock absorbers and linkages that connects a vehicle to its wheels and allows relative motion between the two.
Suspension systems serve a dual purpose — contributing to the vehicle's roadholding/handling and braking for good active safety and driving pleasure, and keeping vehicle occupants comfortable and a ride quality reasonably well isolated from road noise, bumps, and vibrations.

The components of the suspension consist of:
  • Tires
  • Wheels
  • Shock absorbers
  • Mcpherson struts
  • Springs
  • Sway bars
  • Torsion bars
  • A arms
  • Lower control arms
  • Axles
  • Alignment
  • Tire pressure
The various components of the suspension systems of every vehicle are designed to counteraffect the forces of gravity and inertia! Even though every car is different, every system accomplishes the same objective:-
  •  Keeping tires on the road surface. Engineers call this "road holding". It's important for the tires to stay in contact at all times, because friction between the tires and the ground is what lets the car accelerate, stop and corner. The suspension keeps the weight centered to maintain the grip.
  • Stable steering and handling. The suspension keeps the car or truck body from tipping or rolling in a corner.
  • Passenger comfort. Keeps the cabin isolated from the bumps on the road. Suspensions absorb that up-and-down energy and disperse it without too many bobbles.
     How does the Suspension System work?

The suspension system connects your vehicle to its wheels. It is designed to counteract the forces of gravity, propulsion and inertia that are applied to your vehicle as you accelerate, slow down or stop in such a way that all four wheels remain on the ground!

The tires - which are mounted on your vehicle’s wheels (or rims) - are the most important and visible components of the system. They transfer the power of the engine to the ground when your vehicle moves and they counter that motion when it stops.

As you drive over a bumpy road, shocks are absorbed by the combined work of a shock absorber (or damper) and a coil or leaf spring mounted on each wheel. The spring is a device that stores energy in order to supply it later on. It is actually the spring that handles the abuse of the road by allowing the wheel to move up and down with respect to the frame of the vehicle. In return, the shock absorber softens the suspension moves entailed by the spring by “absorbing the shocks”. The shock absorber is a steel or aluminum hydraulic cylinder filled with oil and pressurized with nitrogen. As the suspension moves, a piston is forced to move through the oil-filled cylinder. The energy produced from the motion of the piston is dissipated as heat which in turn is absorbed by the oil.

     Types of suspension system for independent system
  • MacPherson strut type
  • Double wishbone type
  • Semi trailing arm type
MacPherson strut type :
This system is usually use for most widely in independent suspension system for small and medium sized cars.These type are so popular so in FF(Front engine and front wheel transmission)type of car,used as the rear suspension.
Characteristic for MacPherson: The construction of the suspension is relatively simple. MacPherson type,have small number of parts,so when it component is less,then less weight.The effects is unsprung can be reduce.

The space for the suspension is small,the usable space in the engine compartment can be increased. Since the distance between suspension support point is great,there is a little disturbance of the front wheel allingment due to installation error or part manufacturing error.Therefore, except for toe-in,allingment adjustment ordinarily unnecessary.

Double wishbone type:
This is usually used for front suspension for small trucks and for front and rear suspension for passenger cars. Characteristic for double wishbone: Wheels are mounted to the body via upper and lower arm. Suspension geometry can be designed as desired according to the length of the upper and lower arm and their mounting angles.

For example if upper and lower arm are parallel and have equal length,the tread and the tire-toe ground camber of the tire will change.As a result,it is not possible to obtain adequate conering performance.In addition, in the tread will cause excessive tire wear.

To solve this a design is normally employed in which the upper arm is made shorter than the lower arm so that the tread and the tire-to-ground camber of the tire fluctuate less.

Semi trailing arm type:-

Is used for the rear suspension in a few models.With this suspension,the amount by which the toe angle and camber change(due to the up-and-down motion of the wheels) can be controlled at the design stage, in order to determined the handling characteristics of the vehicle.

Signs of troubles related to the Suspension System:
  • Excessive tire wear
  • Poor steering control or off-center steering wheel
  • Excessive bouncing over road bumps
  • Loss of control during sudden stops
  • Excessive swerving while changing lanes
  • Front-end nose diving during quick stops
  • Vehicle sag in front or rear

How Magnetic Bearings Work

A magnetic bearing is a bearing that supports a load using magnetic levitation. Magnetic bearings support moving parts without physical contact.For instance, they are able to levitate a rotating shaft and permit relative motion with very low friction and no mechanical wear.Magnetic bearings support the highest speeds of all kinds of bearing and have no maximum relative speed.

How Magnetic Bearings Work :-


There are three key components in a magnetic bearing system that work together to achieve this new level of performance. First the magnetic bearing itself consists of stationary (stator) components as well as rotating (rotor) components.
  These components create the magnetic field that will support and control the rotor position. The second component is the position sensor. These sensors continuously monitor the position of the bearing rotor relative to the position of the bearing stator.

The third component is the Magnetic Bearing Controller (MBC). This is the ‘brains’ of the system, taking the data from the position sensors and determining how much power it should deliver to each magnetic bearing in order to keep the system stable and under control.

The magnetic bearing stator consists of a stack of steel laminations that are wound with copper wire to form an electromagnet. In operation, a current is supplied to each coil of wire to produce an attractive force that levitates the shaft inside the bearing.

The MBC applies the precise level of current to the coils determined by monitoring signals from the positioning sensors in order to keep the shaft at the desired position throughout the operating range of the machine. Depending on the application, there is typically a 0.5 to 1 mm air gap between the bearing rotor and stator.

 An active magnetic bearing

One if the motst common type of magnnetic bearing is active magnetic bearing (or AMB) is a type of bearing used in high speed rotating machinery that uses electromagnetic forces to levitate a rotating shaft in space, and maintains its position by actively controlling the electromagnets, leaving zero contact between the bearing and the rotating mass.
This magnetic levitation allows a no contact, friction-free operation, elimination of many machine components, and a clean, reliable and efficient machine.

A typical AMB is made up of the following elements:
  • Stator
  • Shaft
  • Sensors
  • Electromagnets
AMBs can be configured as either radial or thrust (axial) bearings.
These elements are shown in the diagram . Power amplifiers supply equal current to two pairs of electromagnets on opposite sides of a rotor.

This constant tug-of-war is mediated by the controller, which offsets the current by equal but opposite amounts of current as the rotor deviates by a small amount from its center position.
 Sensors provide information to the controller for exact rotor position allowing the controller to interpret and control the amount of current provided by the power amplifier.

The sensors are usually inductive in nature and sense in a differential mode. The power amplifiers in a modern commercial application are solid state devices which operate in a pulse width modulation (PWM) configuration. The controller is usually a microprocessor or DSP.

The Application of Magnetic Bearings

For centrifugal air blowers, few technologies can match the energy efficiency and reliability that’s possible with a permanent magnet motor (PMM), active magnetic bearings (AMB) and a variable speed drive (VSD). SKF has designed this advanced combination of components and technologies as a complete package solution that can help manufacturers streamline product design, development and assembly.

Permanent magnet motor
  • Low energy use and cooling requirements
  • High-speed capabilities in a compact design
  • 10%+ more energy efficient than conventional motors at full load and part load
  • Direct drive configuration eliminates gearbox and oil
  • Optimized shaft geometry accommodates large impellers with robust rotor dynamics
Active magnetic bearings
  • Accommodate instant and frequent start-ups and transient surge forces
  • Active control system provides vibration-free performance
  • Capable of speeds in excess of 40 000 rpm
  • Levitate rotating components for friction- and lubricant-free performance
  • Unitized radial and axial bearing modules enable compact packaging and robust performance
Magnetic bearing controller
  • Tracks and registers rotor position up to 15 000 times per second
  • Controls rotor position to within a micron-sized orbit
  • Continuously corrects rotor position by adjusting the power supplied to each electromagnet
  • Instrumentation for integration into the blower control system

How spark plug works

A spark plug  is an electrical device that fits into the cylinder head of some internal combustion engines and ignites compressed aerosol gasoline by means of an electric spark.
Spark plugs have an insulated center electrode which is connected by a heavily insulated wire to an ignition coil or magneto circuit on the outside, forming, with a grounded terminal on the base of the plug, a spark gap inside the cylinder.
Internal combustion engines can be divided into spark-ignition engines, which require spark plugs to begin combustion, and compression-ignition engines (diesel engines), which compress the air and then inject diesel fuel into the heated compressed air mixture where it autoignites. Compression-ignition engines may use glow plugs to improve cold start characteristics

 Spark Plugs and Spark Plug Wires

Spark Plugs deliver electric current from the ignition system to the engine to ignite the engine’s fuel and air mixture.
Bad spark plugs can cause a car hesitates, jerks, or shakes during acceleration or driving. If the spark plugs are new but you see incomplete electric spark, check on the spark plug wires

Ignition System

If both the spark plugs and spark plug wires are working properly. You may have to check on the ignition system.
For car equipped with mechanically timed ignition (usually is older car), check on the distributor, ignition coil, both battery connectors, and all wires.

 Plug Types:-

Some cars require a hot plug. This type of plug is designed with a ceramic insert that has a smaller contact area with the metal part of the plug. This reduces the heat transfer from the ceramic, making it run hotter and thus burn away more deposits. Cold plugs are designed with more contact area, so they run cooler
The carmaker will select the right temperature plug for each car. Some cars with high-performance engines naturally generate more heat, so they need colder plugs.
If the spark plug gets too hot, it could ignite the fuel before the spark fires; so it is important to stick with the right type of plug for your car.

Spark Plugs and Spark Plug Wires

How Four Stroke Cycle Engine Works

Four Stroke Cycle Engine :-

A four-stroke cycle engine is an internal combustion engine that utilizes four distinct piston strokes (intake, compression, power, and exhaust) to complete one operating cycle. The piston make two complete passes in the cylinder to complete one operating cycle. An operating cycle requires two revolutions (720°) of the crankshaft. The four-stroke cycle engine is the most common type of small engine. A four-stroke cycle engine completes five Strokes in one operating cycle, including intake, compression, ignition, power, and exhaust Strokes.

Intake Stroke:-

The intake event is when the air-fuel mixture is introduced to fill the combustion chamber. The intake event occurs when the piston moves from TDC to BDC and the intake valve is open. The movement of the piston toward BDC creates a low pressure in the cylinder. Ambient atmospheric pressure forces the air-fuel mixture through the open intake valve into the cylinder to fill the low pressure area created by the piston movement. 
The cylinder continues to fill slightly past BDC as the air-fuel mixture continues to flow by its own inertia while the piston begins to change direction. The intake valve remains open a few degrees of crankshaft rotation after BDC. Depending on engine design. The intake valve then closes and the air-fuel mixture is sealed inside the cylinder.

Compression Stroke:-

The compression stroke is when the trapped air-fuel mixture is compressed inside the cylinder. The combustion chamber is sealed to form the charge. The charge is the volume of compressed air-fuel mixture trapped inside the combustion chamber ready for ignition. Compressing the air-fuel mixture allows more energy to be released when the charge is ignited. Intake and exhaust valves must be closed to ensure that the cylinder is sealed to provide compression. Compression is the process of reducing or squeezing a charge from a large volume to a smaller volume in the combustion chamber. The flywheel helps to maintain the momentum necessary to compress the charge.

When the piston of an engine compresses the charge, an increase in compressive force supplied by work being done by the piston causes heat to be generated. The compression and heating of the air-fuel vapor in the charge results in an increase in charge temperature and an increase in fuel vaporization. The increase in charge temperature occurs uniformly throughout the combustion chamber to produce faster combustion (fuel oxidation) after ignition.

The increase in fuel vaporization occurs as small droplets of fuel become vaporized more completely from the heat generated. The increased droplet surface area exposed to the ignition flame allows more complete burning of the charge in the combustion chamber. Only gasoline vapor ignites. An increase in droplet surface area allows gasoline to release more vapor rather than remaining a liquid.

The more the charge vapor molecules are compressed, the more energy obtained from the combustion process. The energy needed to compress the charge is substantially less than the gain in force produced during the combustion process. For example, in a typical small engine, energy required to compress the charge is only one-fourth the amount of energy produced during combustion.

The compression ratio of an engine is a comparison of the volume of the combustion chamber with the piston at BDC to the volume of the combustion chamber with the piston at TDC. This area, combined with the design and style of combustion chamber, determines the compression ratio. Gasoline engines commonly have a compression ratio ranging from 6:1 - 10:1. The higher the compression ratio, the more fuel-efficient the engine.

 A higher compression ratio normally provides a substantial gain in combustion pressure or force on the piston. However, higher compression ratios increase operator effort required to start the engine. Some small engines feature a system to relieve pressure during the compression stroke to reduce operator effort required when starting the engine.

Power Stroke:-

The power stroke is an engine operation Stroke in which hot expanding gases force the piston head away from the cylinder head. Piston force and subsequent motion are transferred through the connecting rod to apply torque to the crankshaft. 
The torque applied initiates crankshaft rotation. The amount of torque produced is determined by the pressure on the piston, the size of the piston, and the throw of the engine. During the power Stroke, both valves are closed.

Exhaust Stroke:-

The exhaust stroke occurs whenspent gases are expelled from the combustion chamber and released to the atmosphere. The exhaust stroke is the final stroke and occurs when the exhaust valve is open and the intake valve is closed. Piston movement evacuates exhaust gases to the atmosphere.

As the piston reaches BDC during the power stroke combustion is complete and the cylinder is filled with exhaust gases. The exhaust valve opens, and inertia of the flywheel and other moving parts push the piston back to TDC, forcing the exhaust gases out through the open exhaust valve. At the end of the exhaust stroke, the piston is at TDC and one operating cycle has been completed.

2 Stroke Cycle Engine

A two-stroke, or two-cycle, engine is a type of internal combustion engine which completes a power cycle with two strokes (up and down movements) of the piston during only one crankshaft revolution. This is in contrast to a "four-stroke engine", which requires four strokes of the piston to complete a power cycle. In a two-stroke engine, the end of the combustion stroke and the beginning of the compression stroke happen simultaneously, with the intake and exhaust (or scavenging) functions occurring at the same time.
Two-stroke engines often have a high power-to-weight ratio, usually in a narrow range of rotational speeds called the "power band". Compared to four-stroke engines, two-stroke engines have a greatly reduced number of moving parts, and so can be more compact and significantly lighter................................................................................
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Four Stroke Engine

A four-stroke engine (also known as four-cycle) is an internal combustion engine in which the piston completes four separate strokes which constitute a single thermodynamic cycle. A stroke refers to the full travel of the piston along the cylinder, in either direction. The four separate strokes are termed:
  1. Intake: this stroke of the piston begins at top dead center. The piston descends from the top of the cylinder to the bottom of the cylinder, increasing the volume of the cylinder. A mixture of fuel and air is forced by atmospheric (or greater by some form of air pump) pressure into the cylinder through the intake port.
  2. Compression: with both intake and exhaust valves closed, the piston returns to the top of the cylinder compressing the air or fuel-air mixture into the cylinder head.
  3. Power: this is the start of the second revolution of the cycle. While the piston....................

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Types of Jet Engine

 Content :-

*History of Jet Engines.


*Parts Of Jet Engine.

*How A Jet Engine works.

*Types Of Jet Engine






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