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March 31, 2021
 A flywheel is a rotating mechanical device that is used to store rotational energy. Flywheels have a significant moment of inertia and thus resist changes in rotational speed. The amount of energy stored in a flywheel is proportional to the square of its rotational speed. Energy is transferred to a flywheel by applying torque to it, thereby increasing its rotational speed, and hence its stored energy. Conversely, a flywheel releases stored energy by applying torque to a mechanical load, thereby decreasing its rotational speed.






Flywheel is a circular wheel (or Disc) made up of steel or cast iron (depends upon the application). It also acts as part of clutch mechanism and fluid drive unit. It has teeth on its outer edge which is meshed with the teeth of the electric cranking motor driven pinion and it used to crank (to rotate crankshaft) the engine during its starting.


Working of Flywheel

To understand that lets take an example of working of single cylinder four stroke engine. In four stroke engine we have four strokes i.e. suction, compression, power and exhaust stoke. Only in the power stroke we get power and in the rest of the strokes, the power is required to perform different process like suction, compression and exhaust process. So we need a device which can stores the power during power stroke and deliver that power to the remaining strokes when required. This could be done with the use of a flywheel. The flywheel stores the power during the expansion or power stroke and then imparts this power to the remaining strokes of the engine for its working.

The Flywheel is made of heavy steel or cast iron and it is attached to the rear end of the crankshaft. The weight of the flywheel depends upon the nature of the variation of the pressure, number of cylinder and design of engine.

The weight of the flywheel decreases with the increase in the number of cylinder. It means a two cylinder engine has lighter flywheel as compared with single cylinder engine.


Main Function of the Flywheel

  1. It provides constant power output where there is a fluctuation in the power is observed.
  2. It maintains the constant speed of the engine during all the strokes.
  3. It stores the mechanical energy (rotational energy) of the engine and deliver it  when required.


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March 25, 2021
 This is a smart type of fuel injector which is controlled electronically by the electronic control unit of the engine which is also known as brain of modern engines.

Electronically controlled fuel injectors consist of following parts –






  • Injector body- Same as the mechanically controlled fuel injector the body of this type of injector is a precisely designed hollow shell inside which all the other components are arranged.
  • Plunger- Same as the mechanically controlled fuel injector a plunger is used for the opening and closing of the nozzle but in electronically controlled fuel injector the opening of the nozzle is controlled electronically with the help of electromagnets.
  • Spring – Same as the mechanically controlled fuel injector a plunger spring is used to hold the plunger in its position in order to close the nozzle of the fuel injector when required.
  • Electromagnets – Unlike mechanically controlled fuel injector this type of injector is equipped with electromagnets just around the plunger which controls the opening of the nozzle by taking the electronic signal from the electronic control unit of the engine through the electronic plug or connection connecting the fuel injector with the electronic control unit of the engine.
  • Electronic plug/connection- At the top end of electronically controlled fuel injector a connection/plug is present through which the electronic signal from the electronic control unit of the engine is transferred to the electromagnets which in turn opens the nozzle in order to spray the fuel.

Working 

  • The fuel pump start pumping the fuel to the fuel injector and the timing, amount and pressure of the fuel entering the fuel injector is governed by the electronic control unit.
  • The electronic control unit sends the electronic signal to the fuel injector with the help of the electronic connection, due to these electronic signals from the ECU the electromagnets inside the fuel injector got activated which in turn pushes the plunger outward results in opening of the nozzle and finally the spray of the fuel takes place.
  • After completing this particular cycle the electronic signal from the ECU stops which in turn deactivates the electromagnets due to which the plunger returns to its initial position results in closing of the nozzle and the spray of the fuel stops.
  • The closing of the nozzle is maintained by the plunger spring.
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March 24, 2021

A Traction Control System ( TCS ), also known as Anti-Slip Regulation ( ASR ), is typically (but not necessarily) a secondary function of the anti-lock braking system on production vehicles , and is designed to prevent loss of traction of the driven road wheels, and therefore maintain the control of the vehicle when excessive throttle is applied by the driver and the condition of the road surface (due to varying factors) is unable to cope with the torque applied.






The basic idea behind the need of a traction control system is the difference between the slips of different wheels or an apparent loss of road grip that may result in loss of steering control over the vehicle.


Difference in slip may occur due to turning of a vehicle or differently varying road conditions for different wheels. At high speeds, when a car tends to turn, its outer and inner wheels are subjected to different speed of rotation, that is conventionally controlled by using a differential.


Imagine you are accelerating from a stop on an icy road in a front-wheel drive vehicle without Traction Control. If you accelerate very gently, you might be OK, but if you press the gas pedal just a bit harder, one or both front wheels could lose traction and begin to spin on ice, so the vehicle would be very hard to control.


The Traction Control is designed to help in a situation like this. Once the Traction Control System senses that any of the drive wheel(s) starts slipping, it reduces the engine torque and shortly applies the brake to the slipping wheel(s) to slow it down just enough to regain traction, thus helping you to control your vehicle during acceleration.


Typical Traction Control system is based on vehicle's Anti-lock braking system (ABS) and uses many of ABS components. It utilizes the ABS wheel speed sensors to monitor the speed of all four wheels.


When Traction Control system senses that the wheel looses traction (begins to rotate faster) during acceleration, it applies the brakes to that wheel using the ABS hydraulic module and commands the Engine Control Module to reduce the engine power. When Traction Control system operates, you could probably feel that the engine power is reduced and hear some buzzing noise similar to that of ABS. The Traction Control light may also flash.


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March 08, 2021

 A compression ratio (CR) of an I C engine is the ratio of the total volume of the combustion chamber To the volume left after complete compression i.e. clearance volume. In simple words, it is the ratio between the total volume of the combustion chamber which is left when the piston is at its bottom dead center and the volume left inside the combustion chamber when the piston moves to its top dead center.






For example- Let’s consider an engine having 1000cc total volume out of which 900cc is the swept volume i.e. the volume covered by the piston when it moves from BDC to TDC, and having 100cc clearance volume i.e. the volume left inside the cylinder when the piston reached to its TDC. So the compression ratio of this engine will be 1000:100 or 10:1.

It is found that greater the compression ratio more will be the power output of the engine.

The compression ratio of diesel engine is much higher than that of petrol engine. i.e. for petrol engine the CR varies from 10:1 to 14:1 and for diesel engines, the CR varies from 18:1 to 23:1.


1. Petrol Engine-

If we talk about 4-stroke petrol engine the compression ratio has its own significance that are-

  • As we all know the in petrol engine air-fuel mixture enters the combustion chamber during the suction stroke and for proper mixing and for proper combustion of this air-fuel mixture compression of this mixture is required which is done by the engine in its compression stroke, so a good compression ratio of the petrol engine is required for proper combustion of the air-fuel mixture which in turn provides better thermal efficiency.
  • The pressure inside the cylinder increases during compression stroke which in turn raises the temperature of the air-fuel mixture that leads to complete or proper combustion of the fuel when the spark plug produces spark which in turn provides better fuel economy and also prevents the engine from various defects like knocking.
  • The petrol engine with proper CR provides a balanced amount of power and speed.
  • The petrol engine usually comes with 10:1 to 14:1 compression ratio depending upon the application and design requirement.





2. Diesel Engine-

When it comes to diesel engines the compression ratio has its greater significance as-

  • In diesel engine a high CR is required  as the diesel engine doesn’t  have any spark plug so the combustion of the fuel completely depends upon the compression of the air provided by the compression stroke of the diesel cycle because of which diesel engine is also known as compression ignition engine.
  • The diesel engine with high compression ratio provides the engine with high compression i.e. provides high pressure rise, which is required to increase the temperature of the compressing air to the extent of the auto ignition temperature of the fuel that is to be sprayed by the fuel injectors which in turn provide complete or proper combustion of fuel.
  • The diesel engines are known for providing high power output which is due to the high compression ratio of the diesel engine, as we know higher the CR higher will be the thermal efficiency or work output.
  • A diesel engine with high CR provides high fuel economy due to the higher thermal efficiency provided by the high compression combustion.
  • Diesel engines usually come with higher compression ratios varies from 18:1 to 23:1 depending upon the application and the design requirement.






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February 13, 2021



Ever wondered why some bikes are equipped with conventional telescopic forks while the others get upside down forks? First and foremost, let's get the differences out the way. A fork comprises of a spring and a damping unit inside. Here, the springs act as a compression unit while the dampers, with the help of oil, control its velocity. In essence, both telescopic forks and USD forks have almost similar working components. Despite this, the latter receives more preference over the former. The origin of USD forks dates back to the late 1980s when race teams turned the fork upside down to improve handling.

In a telescopic fork, the chrome part (stanchion) is positioned at the top and held together by a triple clamp while the slider (female portion) sits at the bottom. Turn the entire assembly over and you have an upside-down fork, where the slider sits up top, braced by the triple clamp, and the stanchion is positioned below. Needless to say, the section which undergoes the most amount of stress needs to be strong, and a fatter diameter fork is the best solution. A USD fork works perfectly well in this scenario. Since the fork assembly is essentially turned upside down, the slider now connects to the triple clamp. It’s also longer compared to conventional telescopic forks. As a result, it provides more support. It’s also less likely to flex under hard braking or turning speeds. Thanks to this, bikes with USD forks handle better and provide better feedback.

Additionally, damping cartridges on USDs are slightly better than the damping rod seen on telescopic forks as the damping or spring action is less progressive. The difference extends even further in terms of a fully adjustable USD fork which uses more complex internal parts. This enables the rider to adjust compression, rebound and damping by tinkering with the adjuster placed on top to suit his/her riding style. However, it does have its drawbacks as USD forks are a lot more tricky to work with and disassembling them is a task. On the contrary, conventional telescopic forks are easier to work with due to their basic architecture, be it changing the oil seals or just taking it all apart.

Telescopic Front Suspension

  • The telescopic suspension is cheaper to design and manufacture.
  • This conventional suspension is easy to repair if anything goes south with it.

So, Usually, the commuter motorcycle uses a telescopic suspension as they are not meant to be driven hard. Nor they have to suddenly change direction at high speed. Also, due to the lower cost telescopic suspension makes more sense at a low price. This suspension hampers the performance of high-end motorcycles.

Up-Side Down Suspension

This type of suspension is restricted to only high end and performance motorcycles. In the end, fast motorcycles are all about cornering speeds and lightning-fast direction changes. So, it is the USD fork that allows the rider to extract the most out of the motorcycle without any compromise in performance. This comes at a cost.

  • Exactly COST. USD front forks are way more expensive than conventional telescopic suspension.
  • However, these more advanced USD forks allow more bump absorption that makes the suspension more prone to damage.
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February 11, 2021
Crankshafts:

The crankshaft is an engine component that converts the linear (reciprocating) motion of the piston into rotary motion. The crankshaft is the main rotating component of an engine and is commonly made of ductile iron.




All major components of the engine like piston,connecting rod etc. are supported by this shaft.
Construction Of Crankshaft:

A crankshaft is simply the same as an eccentric, except the eccentric is a much smaller diameter than the shaft itself Crankshaft length mainly depends on number of cylinders are present in engine .Firing order also considered while designing the Crankshaft .





Location :  

Crankshaft is located in crank case . On Crankshaft, Connecting rods and pistons are mounted. The crankshaft rides on bearings which can wear down over time. The bearings support the crankshaft and also the rods which connect the pistons to the crankshaft.

Applications :

It actually part of an engine where the power is available , and this power is transferred in the form of torque to clutch and thereby  gearbox and wheels.The main function is to convert liner motion of the piston to useful rotary motion.


Camshafts:

Camshaft is a part of engine which is responsible for opening and closing of exhaust and inlet valves.As the engines work they need to breathe out exhaust gases and take in fresh air ( charge) for the next cycle to take place . All these processes need to take place at a designated time with respect to each other. These processes are timed through opening and closing of valves and actuation of fuel pumps through a actuating mechanism which is triggered by movement of the crankshaft. The camshaft comes into picture here. The Crankshaft drives through a belt or chain drive the camshaft on which the inlet,exhaust, fuel pump cams are fitted for each unit when the crankshaft rotates it in turn rotates the camshaft which precisely actuate the valve and fuel pumps.




Construction Of Camshafts:

 A camshaft is a long bar with egg-shaped eccentric lobes, one lobe for each valve and fuel injector.

The relationship between the rotation of the camshaft and the rotation of the crankshaft is of critical importance. Since the valves control the flow of the air/fuel mixture intake and exhaust gases, they must be opened and closed at the appropriate time during the stroke of the piston. For this reason, the camshaft is connected to the crankshaft either directly, via a gear mechanism, or indirectly via a belt or chain called a timing belt or timing chain.





Location : 

Depending on the location of the camshaft, the cam operates the valves either directly or through a linkage of pushrods and rockers. Direct operation involves a simpler mechanism and leads to fewer failures, but requires the camshaft to be positioned at the top of the cylinders.

Applications :

This shaft receives the power from crankshaft  (1:2) and operates the engine valves through cam and follower mechanism(generally mushroom headed follower is used to reduce friction b/w cam and follower). 

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February 08, 2021


Slipper Clutch – How Does it Work?

The actual difference between the slipper clutch and normal clutch is the clutch hub. The base of clutch is on the right side and the hub of clutch is on the left side. You can see ball and ramp in the clutch base and ramp and engagement dogs in clutch hub (It may come with or without ball bearings, this one is without ball bearing). In normal operation, when the engine is trying to turn the rear wheel, the flat engagement dogs push on each other, and the clutch drives the motorcycle forward like a normal clutch operation.

During massive deceleration or hard breaking the torque forces the ramps together. To absorb engine braking force the ramps slide up on each other. This action lifts the hub up from the base, in the direction of pressure plate. It slides until the entire braking force is absorbed and then act like a normal clutch. This mechanism is called “spring loaded ball sliding up ramp”. The above process absorbs the engine braking force and partially disengages the clutch from the engine.





When you are riding at high speeds and suddenly you encounter a sharp corner – the obvious reaction would be to slow down by applying the brakes and shifting in lower gear. But what if you have lesser time and you want to shift 2-3 gears at a time? And when you do this, you do it at the cost of damaging the gear box and putting your safety at risk which arises due to engine braking force. As a mechanism to reduce these issues, Slipper Clutch (also known as back torque limiter clutch) was introduced. Slipper Clutch helps by allowing the clutch to partially slip until the engine speed matches your own speed.

In normal clutches, the engine braking force is transmitted to rear wheel via chain drive (or shaft drive) which causes rear wheel to shake, jump or lose traction. This is the main concept behind slipper clutch – to control rear wheel under hard braking and downshifting that causes the rear wheel to lose traction. It is particularly helpful especially on higher displacement bikes where the engine braking force is massive and may cause the motorcycle to go out of control, resulting in a high-speed collision/accident!

Clutch Stake height:

Clutch stack height is more critical in a slipper clutch than in a normal clutch. The slipper clutch tends to work the best with a clutch stack height that is about 1 mm more than the distance between the clutch hub base and the pressure plate.

Clutch Plate:

Clutch plate order for slipper clutches may vary from the original method due to the clutch hub lifting off of the base. Some clutch plates include special friction plate and judder spring apart from steel plate and friction plate to engage the clutch smoother. In such conditions the first plate which is closest to the engine should be a friction plate. The second plate is a steel plate after, followed by special friction and judder spring.

Slipper Clutch Advantages

The following are the advantages of slipper clutch over normal clutch…

  1. Slipper clutch reduces sudden forces on the inside of the transmission and hence, reduces wear and tear on the transmission
  2. Correctly installed slipper clutch improves performance.
  3. It can prevent disastrous rear wheel lock up in case of engine seizure or transmission failure.
  4. It also reduces work of suspension by absorbing engine braking force hence less bumpy ride while cornering.
  5. The rider does not need to concentrate on clutch operation which allows him to concentrate on other things such as body posture, braking etc while cornering.

Slipper Clutch Disadvantages

Practically there are no disadvantages of slipper clutch but hypothetically there are a few, such as…

  • It’s mechanically complex. Some slipper clutches are really complex to install and deal with (not many of them).
  • They are expensive (not against the saving they make by reducing wear and tear of transmission, less suspension movement and increased rider safety).
  • Sometimes you really need the engine braking force to slow down the bike (but how many times?) which can work against the concept and investment on slipper clutch.
  • Slipper clutch can’t give desired results if not adjusted according to requirements.
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