Air Filter

Air filter is a device that is used to remove airborne contaminants such as dust, pollen, etc. We all are aware that we should change our car’s air filter regularly.

Why is it necessary to have air filter?

The air must be cleaned before it is sent to the combustion chamber. If not, we run the risk of sending dust and debris that will affect engine performance. If the debris has any sharp and abrasive material, it will wear the engine parts such as piston and cylinder.

Types of air filter:

There are various types of air filters that offer different life expectancy.

·         Paper Filter: They are the most cost effective air filter. They are also efficient and easy to service. They have to be replaced every 5000 to 8000 miles.

·         Gauze Filter: The biggest benefit of gauze filter is that they can last the entire life of the vehicle. However, they need regular cleaning with the proper air filter cleaning kit. Cotton is usually used as the gauze material. There are 2 types: oil based and dry gauze air filter. Oil based filters are more effective in filtration but will require oil, whereas dry gauze filters will not be that effective in filtration. Overall gauze filters provide a better air flow than the paper filters.

·         Foam Filter: Polyurethane foam material is used in foam filters. The foam filters can last the entire life, provided it is cleaned regularly. Just like the oil based gauze filter, foam filter requires oil. They offer minimal air flow restriction and also high dirt capacity. The high dirt capacity makes it a popular choice in off road vehicles.

·         Stainless Steel Mesh: This type allows a better air flow. Stainless steel filters provided by Hurricane is one of the best in the market. It has uniform microscopic holes to ensure consistent filtration and air flow. The main advantage of stainless steel filters is that no oiling is required and it can be cleaned by simply washing it in water.

Seat Belt Working

Seat belts are also known as safety belts which are designed to safeguard a passenger from getting seriously injured in the event of a collision. The basic idea is to prevent the occupant from being thrown towards the windshield or dashboard.

Law of motion:

Newton’s first law of motion states that “Every object in a state of uniform motion tends to remain in that state of motion unless an external force is applied to it.” This means that when we (as passengers) are travelling in a car at a particular speed, then we will continue to move forward at that same speed even after brakes are applied due to the momentum our body gains. The momentum is higher if there is a collision and hence our body is thrown in front and we get seriously injured.

If a car is travelling at 60 kmph, then everything in the car is in inertia. If the car hits a pole on the road, then the car abruptly stops, but the occupants in the car will be hurdled in front due to the inertia that they carry. Seat belts act against this inertia to slow us down.

Three Point Retractable Lap and Shoulder Seat Belts:

This is the most commonly used seat belt system for passenger cars worldwide.

Seat Belts Working (Retractor mechanism):

This is the most commonly used mechanism in seat belts. The retractor mechanism uses a spool as its central element. The spool is attached to one end of the webbing. A spring is available inside the retractor that provides a rotational force.

When we pull the webbing (fabric belt) out, the spool rotates in anti-clockwise direction. The rotation of spool also rotates the attached spring in the same direction. The spring will resist the twisting motion and will want to return to the original shape. As soon as we release the webbing, the spring untwists itself in clockwise direction and therefore the spool also rotates in clockwise direction until there is no more slack in the webbing.

The Retractor Locking Mechanism:

In the event of a collision, the retractor has a locking mechanism that stops the spool from rotating. The basic idea of a locking system is to lock the spool from rotating in order to prevent the occupant from being thrown towards the dashboard.

The locking mechanism nowadays uses two sensors to lock the spool. The first is the vehicle deceleration sensor that detects any sudden deceleration in the vehicle and the second is the webbing sensor to detect any violent pull outs of the webbing.  

A centrifugal clutch system is used to lock the spool. When the spool rotates slowly, the centrifugal lever doesn’t pivot at all. When there is a violent rotation of the spool, the lever’s centrifugal force overcomes the spring force and the clutches get locked with the teeth of the spool. The video will clearly show you how this works.

         

Pretensioners:

A conventional seat belt locking mechanism will only lock the rotation of the spool. A pretensioner will actually pull the belt in once the car comes to an abrupt stop. Therefore, it helps move the occupants in the opposite direction of the momentum that tends to carry them forward.

Modern day pretensioners use pyrotechnics to pull in the belt. It consists of a separate gas chamber with an igniter material. When the sensor detects collision, the igniter material is ignited by passing electric current through it. The collision is detected by a central processor which then sends the electric current to the igniter. The ignition releases gases at a huge pressure which pushes the piston upwards. A rack gear is provided at the top of the piston which moves up and engages with the spool gear and rotates the spool forcefully to pull the belt inside.  

Another angle of the pre-tensioner

Load Limiter:

In very violent crashes, seat belts can incur serious damages on the occupants, especially the old people who cannot take much load on their rib cages. The harder the impact of collision, the harder will be the force of the seat belt to stop the occupant.

The basic idea of introducing a load limiter is to limit the force of the pretensioner on the occupants. Load limiter allows the belt or webbing to extend a bit more when a great deal of impact is applied on it. The best way to achieve this is by integrating a torsion bar with the retractor mechanism. The torsion bar is attached to the locking mechanism on one end and the spool on the other end.

When the impact force is less, the torsion bar will be steady and will allow the spool to be locked along with the locking mechanism. When the impact is very high, then the force will twist the torsion bar slightly, thus allowing the spool to rotate and extend the webbing a bit more.

Seat belts work in combination with the airbags and hence it is necessary that the airbags deploy in order to save the occupant from injuries.

Learn about airbags in this link:

• Airbags

Airbags

Newton’s first law of motion states that “Every object in a state of uniform motion tends to remain in that state of motion unless an external force is applied to it.” This means that when we (as passengers) are travelling in a car at a particular speed, then we will continue to move forward at that same speed even after brakes are applied due to the momentum our body gains. The momentum is higher if there is a collision and hence our body is thrown in front and we get seriously injured. Air bags provide a cushion to our body in the event of a collision to prevent any serious injury.

Air bag is a safety device used in vehicles that consists of a flexible fabric bag that inflates instantaneously in the event of a collision to protect the driver and passengers from serious injury to their head, face and chest. Air bags are like a soft pillow to land against in the event of a crash. The purpose of an air bag is to slow the forward motion of the passenger in a fraction of a second.  

Air bags were first introduced commercially for automobiles in 1980. Looking at the reduction in fatalities, U.S made it mandatory for all cars to be installed in cars since 1998.

Where is air bag installed?

Typically air bags are installed in the steering wheel for driver and in the instrument panel for the front passenger. Apart from that, in high end luxury models, door mounted side air bags and seat mounted air bags are also installed.

Working of an air bag:

The air bag consists of a thin nylon bag which is folded inside the steering wheel or dashboard. There is a crash sensor that detects any crash when the vehicle collides. The crash sensor signals the inflator to inflate the air bag when necessary.

Air bags will inflate only if the vehicle achieves a minimum speed of 16 to 14 kmph. When crash occurs, accelerometer sends the information to the crash sensor. The crash sensor then actuates the inflation system. The inflation system in older air bags sets off a chemical reaction between sodium azide (NaN₃), potassium nitrate (KNO₃) and silicion dioxide (SiO₂) to form nitrogen gas. The hot blast of nitrogen gas inflates the nylon bag. The bag is covered with talcum powder for its lubrication and to help it inflate smoothly.

Solid propellant inflators:

Solid propellant inflation systems are used to rapidly produce nitrogen gas in huge amount to inflate the nylon bag. The airbag circuit passes the current to the heating element. The heating element heats up sodium azide (NaN₃) which acts as an explosive.

2 NaN₃     →    2 Na + 3 N₂

10 Na + 2 KNO₃     →     K₂O + 5 Na₂O + N₂

K₂O + Na₂O + SiO₂     →     Na₂K₂SiO₄ (alkaline silicate glass)

Sodium azide decomposes at 300°C to form sodium and nitrogen gas.  The highly reactive Na metal is removed by KNO₃ and SiO₂ and in turn produces nitrogen gas. The K₂O and Na₂O formed suring second reaction is highly reactive and reacts with SiO₂ in the third reaction to form silicate glass which is harmless and stable.

The gas travels at more than 300 kmph and inflates the bag completely in 60 to 80 milliseconds from point of collision. The bag has small pores which lets the nitrogen gas to escape after few seconds of inflation.

Safety Concerns with Airbags:

Airbags best work as a supplement to seat belts. Hence, it is also known as Supplement Restraint System (SRS). The force of an airbag can also hurt if the driver is sitting too close to the steering wheel. It is recommended to be at least 10 inches away from the air bag or steering wheel.

Learn about Seat belts by going to this link:

• Seat Belts

Leaf Springs

Leaf springs are commonly used for suspension in vehicles. It is one of the oldest forms of suspension and is used commonly in trucks and other heavy duty vehicles. Leaf springs are also available in most of the pickup trucks at the rear axle.

Design:

They are long and thin steel metal plates attached either above or below the axle. The metal plates are slightly curved and looks like a bow. The ends of the leaf springs are provided with eye-holes so that they can be attached to the vehicle body. Depending on the number of leaf and the number of eye holes, leaf springs can be divided into different types.

Based on the number of leaf:

·         Monoleaf Springs: These springs consist of only one steel plate in a curved shape. Such plates are thick at the center and get thinner on the edges. The shape is in the form of a semi-elliptical curve. They don’t offer good strength and suspension. Heavy duty vehicles require multileaf springs to provide the strength.

·         Multileaf Springs: It consists of various steel plates of different lengths stacked upon each other. The shortest leaf is kept at the bottom and the longest is kept at the top to give the same semi-elliptical shape that single leaf springs provide. Multiplate springs are provided with rebound clips to hold the plates together.

Based on the number of eye hole:

·         Double eye leaf springs: The longest steel plate in a leaf spring is provided with eye holes on both the sides so that it can be easily bolted to the body of the vehicle.

·         Open eye leaf spring: Only one end is provided with an eye hole. The other end is either flat or provided with a hook.

Purpose of U-bolts in a leaf spring:

Just by securing the eye holes of the spring to the hanger of the frame won’t be enough to steady the leaf springs. The leaf springs might be suspended or attached loosely to the axle of the vehicle. Such conditions lead to overslung and underslung. Overslung occurs when leaf spring is placed over the axle. Underslung occurs when the leaf spring is attached under the axle.

U-bolts are horse shoe shaped metal rods that avoid the overslung and underslung condition. A pair of U-bolts are fit around the axle and bolted to a metal plate that supports the leaf springs and also keeps the metal plates in the leaf spring intact without moving too much when carrying heavy load.

What makes leaf springs so strong?

The number and thickness of these leaves are what decide the spring rate and load capacity. The length of the leaves will decide the ride quality and the width decides the stability. Leaf springs are also known as progressive rate springs because of their tapered design. They grow stiffer when they are compressed which gives them the strength for carrying heavy loads.

Advantages of leaf spring:

·         It doesn’t require an anti-roll bar as leaf springs are twice as stiff in roll as it is in bump. Hence we can reduce weight and cost of extra material.

·         It provides great stability at high loads.

·         It is simple in design and easy to install.

·         The load distribution is even on both the sides of the axle. If a leaf spring is fitted with a shock absorber, then the load on the top of the shock absorber will be drastically reduced.

·         Leaf spring can be mounted in the centre, above or below the drive shaft without affecting the wheel movements. The advantage of this setup is that there will be no off-centre loads like we see in a coil spring.

Disadvantages:

·         Leaf springs are much heavier than coil springs. One leaf will weigh more than two coil springs combined together.

·         Takes up a lot of space.

·         Leaf springs cannot be tuned to adjust with the conditions. Coilovers have a modular design which makes it easy to adjust the ride height and spring rate.

·         Leaf springs are susceptible to noise.

·         Friction occurs between the contacting surfaces of the plates which wears out the leaves and can ultimately lead to a crack.

·         Life of leaf springs is lower than coilovers.

Cylinder Deactivation

Cylinder deactivation is a method of creating a variable displacement engine by means of deactivating one or more cylinders to provide better fuel economy. This method can supply full power at high loads where all the cylinders will be active and can also provide better fuel economy at low loads by deactivating cylinders.

The Purpose for Cylinder Deactivation:

The main purpose of a variable displacement engine is to reduce emissions and fuel consumption at low load conditions. In a conventional fixed displacement engine running at low load condition, the engine delivers only 30% of its power to the power train. The throttle valve is only partially open at low load condition which makes the engine utilize more power to draw the required air through the small opening. This condition is known as pumping loss. Therefore, driving a large capacity engine at low load will result in lower cylinder pressure and hence poor fuel economy.

By shutting down one or two cylinders at low loads, the number of cylinders drawing in air from the intake manifold will be less and hence helps in increasing the air pressure. Also the fuel will be supplied to only fewer cylinders, which will significantly increase the fuel economy. The fuel consumption can be reduced by 8% to 25% at low load conditions.

Principle of operation:

Cylinder deactivation is achieved by closing both the inlet and exhaust valves of a cylinder. This allows the throttle valve to open further to allow more air to flow in to create constant power. Better air flow reduces pumping loss on the piston. Hence, the cylinder pressure increases as the piston reaches the top dead centre (TDC). As a result, effective amount of power is unleashed to rotate the crankshaft.

When the intake and exhaust valves are kept closed, the exhaust gases are trapped inside the combustion chamber. The exhaust gases are compressed during the piston upstroke and expanded due to the piston down stroke movement. The compression and expansion of exhaust gases adds no extra load on the engine and this is also known as ‘air-spring’.

Methods of Cylinder Deactivation:

There are 2 methods to achieve cylinder deactivation:

·         Pushrod Design

·         Overhead Cam Displacement Design

Pushrod Design:

In this method, solenoid is used to alter the oil pressure supplied to the hydraulic valve lifters. When a cylinder is deactivated, the corresponding valve lifter is collapsed by cutting the oil pressure. Once collapsed, the lifters are provided with an internal mechanism which enables the lifter to telescope within itself when the oil pressure is cut off. The lifter won’t be able to lift the pushrods and therefore the rocker arms won’t be able to actuate the valves.

Overhead Cam Displacement Design:

The camshaft has longitudinal splines. Cam units are mounted on these splines which can be displaced axially. The cams can be axially displaced on both the intake and the exhaust sides. The cam units have 2 cam contours per valve. One contour has cam lobe which operates the valve. The other contour has a continuous circular base.

The cam units are displaced with the help of a double actuator. The actuator shifts the cam units so that the contour with the cam lobe is replaced by the contour with a continuous circular base. As a result, the rocker arm stays motionless and the valve remains closed.

   

                    

Dual Clutch Transmission

Dual clutch transmission (DCT) uses a set of two clutches to operate the odd and even gear sets separately. One clutch is used to operate even set of gears and the other clutch will operate the odd set of gears. It is also known as semi-automatic transmission.

Working Principle:

When we look at a conventional manual clutch transmission, a clutch pedal is used to first cut off the power supply from the engine to the gearbox and then gear stick shift is used to change the gear and then later on releasing the clutch pedal, the clutch is engaged with the flywheel and the power supply from the engine to the gearbox resumes. Therefore, there is no continuous flow of power from engine to wheels. This results in torque shifts and can result in the passengers thrown forward or backward as gears are changed by an unskilled driver.

In the case of DCT, there is no clutch pedal. The clutches are controlled by suitable electronics and hydraulics mechanism. One clutch will control the odd gear ratios (1, 3 and 5) and the other clutch will control the even gear ratios (2, 4). The trick behind this is to achieve lightning fast gear changes without interrupting the power supply from the engine.

Design of Dual Clutch Transmission:

A dual clutch transmission uses 2 multiplate clutch assemblies. Even single plate clutches can be used instead of multiplate clutches. There are 2 transmission shafts that carry the power from engine to the gearbox. The outer transmission shaft is connected to the outer clutch assembly.

The outer transmission shaft is hollow, which allows us to insert the inner transmission shaft and connect it to the inner clutch assembly. The outer transmission shaft is supplies power to the even gears (2 and 4) and the inner transmission shaft supplies power to the odd gears (1, 3 and 5).

Both the clutches are controlled hydraulically. It consists of a piston assembly placed against a stack of clutch plates and friction discs. When clutch is engaged, hydraulic pressure from the piston forces the clutch plates and friction discs to move against the pressure plate. The entire clutch assembly is locked and rotates together as a single unit. When the clutch is disengaged, the return springs help to pull the clutch plates and friction discs so that the transmission shaft rotates freely.

Working:

To understand the working in a better way, I suggest you to learn how a manual transmission works by clicking on the following link:

How manual transmission works?

The gear shifting is similar to a conventional manual transmission. Dog clutch and synchronizers are used to engage an individual gear to the output shaft.

1^st Gear:

The inner clutch assembly is engaged and the dog clutch engages itself with the 1^st gear on the output shaft. Make a note that the outer clutch will be disengaged during this process. Once we reach a high enough speed in the 1^st gear, the selector rod will automatically engage the dog clutch to the 2^nd gear on the output shaft. As soon as the outer clutch is engaged, the 2^nd gear is achieved in no time.

When the outer clutch is engaged, the inner clutch will be disengaged, hence cutting off the supply through 1^st gear.

2^nd Gear:

The outer clutch assembly is engaged now and since the dog clutch is already connected with the 2^nd gear, instantaneous acceleration is achieved. The inner clutch will be disengaged during this process.

3^rd Gear:

When the speed in the 2^nd gear is high enough, the dog clutch engages with the 3^rd gear in order to be ready to supply the power during gear shift. As soon as the inner clutch is engaged and outer clutch is disengaged again, the 3^rd gear is achieved. The inner and outer clutch engagement cycle continues for every odd and even gear shifting.

4^th and 5^th Gear:

The outer clutch is engaged to achieve 4^th gear and inner clutch is engaged to achieve 5^th gear.

Reverse Gear:

Reverse gear can be controlled by any one of the clutches. In this case, the outer clutch is used to achieve reverse gear. An idle gear ‘I’ is inserted to mesh between the gears ‘H’ and ‘R’ to reverse the rotation of the wheels.

Advantages of DCT:

·         Even with automatic engagement and disengagement of clutch, drivers can tell computers when to take action with the help of paddles or gearshift.

·         It provides smooth acceleration by avoiding torque shifts or gear shift shocks that are usually experienced in a car with manual transmission.

·         Fuel economy can be improved dramatically by up to 10%.

·         Can handle high torque demands of high performance cars.

The only main disadvantage of DCTs would be the manufacturing cost of it since they involve two clutches and two transmission shafts.

 Related topics:

• Continuously Variable Transmission (CVT)

• How manual transmission works

• Sliding Mesh Gearbox

• Multi Plate Clutch (Spring Type)

• Single Plate Clutch

• Front Wheel Drive (FWD)

• Things not to do in a manual transmission

How do gasoline engines differ from diesel engines?

Both gasoline and diesel engines are 4 stroke Internal Combustion Engines, but both work in a different way. These 2 engines can be distinguished by the way they ignite the fuel. While gasoline relies on spark plugs to ignite the fuel, diesel can be self ignited due to the high temperature and pressure inside the combustion chamber.

Another difference between the 2 engines in the compression ratio. The compression ratio of gasoline engines is in the range of 6:1 to 10:1, and it can go up to 12:1 for higher octane gasoline. Diesel engine's compression ratio is between 16:1 to 20:1.

Petrol engines are quick burn engines, which result in faster combustion of the fuel and hence more power is generated compared to diesel engines. Diesel engines are slow burn engines and hence more time is taken to burn the fuel, resulting in higher torque than gasoline engines.

Air-fuel mixture can be sent in the suction stroke of gasoline engines, which makes it a homogeneous mixture engine. Air and diesel don't mix well at room temperature and hence cannot be sent together in the suction stroke of diesel engine, hence it is called heterogeneous mixture engine.

To know more about the working of both petrol and diesel engines, click the link below:

Spark Ignition (S.I) engine

How Car Parts Work: Diesel Engine

Two Stroke Engine

How Car Parts Work: 6 stroke engine

Two Stroke Diesel Engines

Types of 6 Stroke Engines

Single Piston models:

·         The Bajulaz 6 Stroke Engine:

It was invented in 1989 by Roger Bajulaz of the Bajulaz S.A Company in Geneva, Switzerland. It is similar to a conventional engine with 2 additional fixed capacity chambers in the cylinder head. One of the two fixed capacity chambers is a combustion chamber and the other is an air pre-heating chamber. The combustion chamber receives a charge of heated air from the cylinder and simultaneously fuel is injected into it. Both air and fuel mix in the combustion chamber and is compressed and burnt to a high pressure. The high pressure gained is then sent to the cylinder to achieve the power stroke.

Meanwhile, the air pre-heating chamber heats the air to a high degree. The chamber is in the surrounding of the cylinder wall so that the air is heated due to the combustion process inside the cylinder. The heated air is sent to the cylinder during the 5^th stroke.

The fuel consumption can be reduced dramatically by up to 40% and also the pollution is significantly reduced.

·         Velozeta 6 Stroke Engine:

In this type, air is injected at the end of exhaust stroke (4^th stroke) so that the air expands due to the heat in the chamber and provided a supplementary expansion stroke. It is more of a gas scavenging process to clean up the combustion chamber completely before next air-fuel intake stroke. This engine showed 40% reduction in fuel consumption and was developed in the year 2005 by a team of Mechanical engineering students from India; U Krishnaraj, Boby Sebastian, Arun Nair and Aaron Joseph from College of Enginnering located in Trivandrum.

·         Dyer 6 Stroke Engine:

It was invented in 1915 and it uses water as the working fluid after exhaust stroke. Water is injected into the combustion chamber after exhaust stroke which is instantaneously converted into steam. The steam expands and forces the piston down from TDC to BDC to provide an additional power stroke. Later in 2006, Bruce Crower applied a patent for an engine working on similar principle.

·         NIYKADO 6 Stroke Engine:

This engine was designed and patented by Chanayil Cleetus Anil of Kochi, India in 2012. The model works on air injection at the end of exhaust stroke and it claims to be 23% more fuel efficient than a conventional 4 stroke engine.

  

Opposed Piston Models:

·         Beare Head:

It was designed by Malcolm Beare of Australia. This design allows 2 opposing pistons to move in a single combustion chamber. One piston is used for 4 stroke operation at the bottom end and the other opposing piston moves at half the rate of the 4 stroke piston. The opposing piston replaces the valve mechanism by opening and closing the inlet and exhaust ports. It claims to increase the power by 9%.

6 stroke engine

A 6 stroke engine is an improvement over the current 4 stroke engine used in automobiles. Consider a 4 stroke engine with 4 strokes (intake, compression, power and exhaust); a 6 stroke engine provides an extra power and exhaust strokes. The heat of combustion which is leftover after the exhaust stroke (4^th stroke) is used to create an additional expansion stroke. Air or water can be used as the fuel for the 5^th stroke.

Working Principle of 6 Stroke Engines:

The principle of 6 stroke engines is to capture the waste heat from the 4 stroke Otto cycle or Diesel cycle and utilizing the waste heat to generate an additional power stroke and exhaust stroke. Air or water is used as the working fluid for the additional power stroke.

Design of 6 stroke engines:

The design is pretty much similar to a conventional 4 stroke internal combustion engine. The piston moves up and down the combustion chamber. Apart from the existing intake and exhaust valves, there are additional air suction valve and air exhaust valve for the 5^th and 6^th strokes respectively.

WORKING OF 6 STROKE ENGINES:

1^st Stroke (Intake stroke):

Consider a 6 stroke engine with Otto cycle; the intake valve opens and air-fuel mixture is sucked into the combustion chamber due to the piston movement from top dead centre (TDC) to bottom dead centre (BDC). The movement of piston from TDC to BDC creates negative pressure in the cylinder, which sucks in more air-fuel mixture.

2^nd Stroke (Compression stroke):

In the compression stroke, all 4 valves will remain closed. The air-fuel mixture is trapped inside the combustion chamber. Now the piston starts moving from BDC to TDC and compressed the air-fuel mixture inside the combustion chamber.

3^rd Stroke (Power stroke):

Just before the piston reaches the TDC in the combustion chamber, a spark plug ignites the compressed air-fuel mixture. This generates a lot of heat and the piston is forced to move down from TDC to BDC. The expansion of gases releases energy (horsepower) which is used to run the vehicle. All 4 valves remain closed during this operation.

4^th Stroke (Exhaust stroke):

The exhaust valve opens and the movement of piston from BDC to TDC pushes the exhaust gases out through the exhaust valve. Now we are quite familiar with these 4 strokes in a conventional 4 stroke engine. We also are aware of the fact that there is some leftover heat in the combustion chamber after the exhaust stroke. The leftover heat is used in the 5^th stroke.

5^th Stroke (Air Suction):

Fresh air from the atmosphere is sucked in through the air suction valve. The high temperature inside the combustion chamber heats the fresh air and this leads to expansion of air which forces the piston to move down from TDC to BDC to provide an additional power stroke. The air can also be pre-heated before being sent into the combustion chamber. Pre-heated air will result in better expansion.       

6^th Stroke (Air Exhaust):

The air exhaust valve opens and as the piston moves up from BDC to TDC, the expanded air is sent out through the exhaust. This provides better gas scavenging.

In some cases, even water can be injected inside the combustion chamber after 4^th stroke. The water is converted into steam due to heat and creates an auxiliary power stroke.

Advantages of 6 Stroke Engines:

·         Higher fuel economy up to 40%

·         No cooling system required as heat is carried away during 5^th and 6^th stroke

·         Significant reduction in emissions

·         Two power strokes for 6 strokes

·         Can run on multiple fuels, including LPG

Types of 6 Stroke Engines:

There are several designs of 6 stroke engines that work on different concepts to generate an additional power stroke and exhaust stroke.

Types of 6 stroke engines

  

      Related Topics:

• Spark Ignition Engines (Gasoline)

• Two Stroke Engine

• Diesel Engine

• Rotary Engines

• Engine Layouts

• Two stroke Diesel Engine

• Peugeot MCE-5 VCR Engine

• Variable Compression Ratio Engine

Things not to do in a manual transmission

In this article, I will talk about 5 bad habits that one may follow while driving a manual transmission vehicle. Not following these don’ts might affect the transmission and engine performance of the vehicle.

1.       Don’t rest your hand on the gearshift:

This habit is commonly seen among the experienced drivers who prefer to rest their hand on the gearshift and steer the vehicle with the other hand. We all know that during gear shift, selector fork engages the dog clutch to the respective gears.

If we rest our hand on the gearshift, we might apply unwanted pressure on the selector fork against the dog clutch. This can lead to wearing of the selector fork and the dog clutch. The scenario looks like forcing gear change without pressing on the clutch pedal which can damage the components.

The best way to deal with this situation is to use both the hands for steering. Gearshift should be touched only while changing the gear. Whenever you need a gearshift, press the clutch pedal, use your hand to shift the gear and then put your hand back on the steering wheel.

2.       Put the transmission on neutral at the stop light:

Drivers should have the practice of leaving the vehicle at neutral at stop lights instead of pressing on the clutch pedal and shifting to 1^st gear. The clutch assembly has a release bearing which presses against the diaphragm spring when the clutch pedal is pressed. This applies unnecessary pressure on both the release bearing and the diaphragm spring which leads to wearing.

The best thing to do is to bring the gearshift to neutral and release the clutch pedal to avoid any unnecessary wearing within the clutch.

3.       Never use clutch to hold the vehicle on a slope:

When you have halted your vehicle on a steep hill, there is always a tendency for the vehicle to roll back. In this scenario, we should never use the clutch to hold ourselves from rolling back, as the clutch plate and pressure plate would be rotating at different speeds and this would lead to the wearing of the friction material on the clutch plate.

Hand brakes come in handy under this situation. Apply hand brakes to prevent the vehicle from rolling back. When you want to move forward, press on the clutch pedal and shift the gear to 1^st gear. Then slowly start releasing the clutch pedal. As you feel a forward movement, quickly release the handbrake and then press on the accelerator to get the forward movement. With regular practice, one should be able to control it perfectly.

4.       Downshift the gear at lower vehicle speed:

On some occasions people get lazy to downshift the gear at a lower vehicle speed. In other words, we shouldn’t apply a lot of throttle when we are at a lower engine rpm. For example, if you are at 5^th gear and the vehicle is running at 40 kmph, it is not a good idea to press on the throttle because the engine will be at a huge gearing disadvantage. You are simply going to ask the engine to put more effort to accelerate the vehicle. This will affect the fuel economy.

So if you are running the car at a lower speed, it would be in your best interest to downshift to a lower gear for better and smoother acceleration.

5.       Don’t rest your foot on the clutch pedal:

Resting your foot on the clutch pedal can affect the power transmitted to the transmission because the clutch may not be fully engaged. In this situation, you might also be wearing the clutch disc due to slipping.

6.       Don’t start your vehicle at 2^nd gear:

This is again commonly seen among professional drivers who seem to have better control over clutch pedal. Moving the vehicle by up-shifting directly from neutral to 2^nd gear will lead to engine lugging. It simply means you are asking the engine to put more effort in accelerating your car which can be done quite easily at 1^st gear. We all know the fact that the transmission transmits maximum torque at 1^st gear; hence it is always desirable to launch the vehicle at 1^st gear.

       


Other Topics:

• Top 12 features of U.S President's car

• How manual transmission works

• Sliding Mesh Gearbox

• Multi Plate Clutch (Spring Type)

• Single Plate Clutch