fight against corruption

Anna fast enters 5th day; awaits Govt call for dialogue

PTI Social activist Anna Hazare offers water to a kid during his fast at Ramlila Maidan in New Delhi on Friday.

Anna Hazare’s fast demanding a strong Lokpal entered the fifth day on Saturday with his Team saying they were ready to talk to the government but no such communication channels have been opened.

Mr. Hazare came to the podium at around 10 a.m. as supporters started pouring in Ramlila Maidan where he launched his protest on Friday after coming out of Tihar Jail.

The 73-year-old anti-corruption crusader alleged the funds in government treasuries were being threatened not by thieves but from those guard it and the country is being threatened by these traitors.

“Why should we fight? The funds in government treasuries are ours. The treasuries are not threatened by thieves but by those who guards it. The country is not betrayed by enemies but by these traitors,” the social activist said.

He said he has lost three-and-half kg in the last four days. “I feel a little weak. But there is nothing to worry about it. The fight will go on till we get a strong Lokpal,” Mr. Hazare said in his brief address to the gathering.

'Ready to talk to Govt'

His close associate Arvind Kejriwal and Manish Sisodia said the Team was ready to talk to the government on the issue of Lokpal Bill but no one has approached them.

“We are ready to talk to the government but there is no communication from their side. Where should we go to talk and whom should we talk to?” Mr. Kejriwal and Mr. Sisodia said.

Mr. Hazare had on Friday raised the political stakes by giving a deadline to the government to pass the Jan Lokpal bill by August 30 failing which he would continue his fast “till my last breath”.

On deadline

On the deadline, former Law Minister Shanti Bhushan said the government can pass it within days if it has a “strong will” to do it.

“It can happen. I have been a Union Law Minister and I know how things happen in government,” he told the gathering.

Asked whether the deadline was a little impractical, Mr. Kejriwal told reporters, “If the government desires, it can pass 15 bills in five minutes. But for the anti-corruption bill, they are taking more than 42 years. So we want to know how many more years will they take?”

The government version encourages corruption and saves the corrupt, Mr. Kejriwal alleged and demanded that the Lokpal Bill introduced in Parliament be “rejected completely” and the Jan Lokpal Bill be replaced by it.

'Waste of time'

Reacting to the newspaper advertisements seeking suggestions from public on Lokpal Bill, Mr. Kejriwal said it appeared to be an exercise which will waste the time of people and Parliamentarians.

“We appeared before the Standing Committee earlier and told them that the present bill is actually for promotion of corruption and save the corrupt people. It ends up in targeting those who complain against corruption,” he said.

Mr. Kejriwal said they had urged the Standing Committee to reject the bill and send it back to Parliament. “It is wasting precious time on a wrong and faulty bill,” he said.

“This seeking of feedback is basically to divert attention,” he said.

Asked about some MPs, including BJP’s Varun Gandhi, planning to introducing Jan Lokpal Bill as private bills, he said private bills do not achieve much.

Earlier in the morning, police conducted extensive searches in the Maidan to ensure that no suspicious objects were planted there. 

supporters:

 

in ahmedabad

 car carying anna to ramlila maidan

 

 supporters in mumbai

‘Anna to come out only if allowed to fast without conditions’

PTI

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PTI Supporters of social activist Anna Hazare protest at the gate of the Tihar Jail in New Delhi on Wednesday.

Anna Hazare and his team were in discussions with the government and police on Wednesday over the venue of his fast after he comes out of Tihar.

After meeting Mr. Hazare, lawyer Prashant Bhushan told the crowd of supporters outside the jail that the Gandhian would come out of jail only if he is allowed to fast without conditions.

Mr. Bhushan said government and police were discussing with Mr. Hazare and his aides options of fast venue — J.P. Park or Ramlila Maidan — where he could launch his fight for a strong Lokpal Bill.

He said if conditions are imposed, then Mr. Hazare will continue with his fast inside the jail.

He also told the crowd that people of Delhi have been asked to come to India Gate for a march to Jantar Mantar in support of Jan Lokpal and fight against corruption.

Mr. Hazare had earlier sought permission from Tihar Jail authorities for a meeting with some of his top associates to plan his strategy.

The meeting was attended by Mr. Bhushan, Kiran Bedi, Medha Patkar, Manish Sisodia and Swami Agnivesh. Deputy Commissioner of Police (Crime) Ashok Chand was also present at the meeting.

Mr. Hazare also met Sri Sri Ravishankar and yoga guru Baba Ramdev in the prison.

Mr. Hazare, who was ordered to be released on Tuesday night after a day-long detention before he was to begin his fast demanding a strong Lokpal, had refused to come out of the prison unless he was allowed to protest from J.P. Park without conditions.

Earlier, Ms. Bedi and Swami Agnivesh announced to the hundreds of supporters waiting since last night that the 74-year-old Gandhian was about to come out of the prison anytime now.

“The government has bowed down. We will have to be prepared to go to J.P. Park in a peaceful manner,” Swami Agnivesh said.

Solidarity with Anna

Ms. Bedi, Swami Agnivesh and Ms. Patkar joined hundreds of protestors on Wednesday expressing solidarity with Mr. Hazare outside Tihar while a large number of the Gandhian’s supporters took out marches across the city.

Mr. Hazare’s supporters in huge numbers also gathered outside Chhatrasal Stadium, which was converted into a special detention area on Wednesday morning and shouted anti-corruption slogans demanding that the Gandhian be allowed to protest at J.P. Park.

Ms. Bedi, who was detained on Tuesday and released later, and Swami Agnivesh arrived outside Tihar at around 11.30 a.m. where a swarm of protestors had gathered since Tuesday night to express solidarity with Mr. Hazare.

Ms. Patkar, who reached the protest spot early in the day, was granted permission to meet Mr. Hazare after being initially refused to enter the premises.

Ms. Patkar approached jail authorities seeking permission to meet Mr. Hazare, who was lodged in the administrative block after he refused to be released, but was initially denied. However, later the authorities changed their stand and allowed her.

After the permission was denied, Ms. Patkar claimed that jail authorities told her that Mr. Hazare was not in their custody and could not allow her to meet him. “It was a right to meet a man in jail. They told me that he is not in their custody and he is not a jail bird. Nobody could be given permission. This is a conspiracy of the government. They are not tolerating any basic rights,” she said addressing the protestors gathered outside Tihar Jail.

At Chhatrasal Stadium, scores of people holding tricolour marched on the tracks while others lent support to them from outside. 

Ramdev, Sri Sri Ravishankar join protesters at Tihar jail:

Yoga guru Ramdev and the Art of Living Foundation head Sri Sri Ravishankar on Wednesday joined protestors expressing solidarity with Anna Hazare outside Tihar Jail.

Baba Ramdev, with whom Mr. Hazare and his associates have differences due to his alleged links with Hindutva elements, reached Tihar Jail on Wednesday afternoon.

Earlier, Baba Ramdev submitted a memorandum against Mr. Hazare’s arrest to President Pratibha Patil.

Addressing protesters, Baba Ramdev termed Mr. Hazare’s arrest as a “conspiracy in the name of democracy”.

“Anna is fighting for a strong Lokpal and his dream will be fulfilled. The whole country and all patriotic countrymen are with him in this struggle,” he said.

Activists Kiran Bedi, Swami Agnivesh and Medha Patkar had earlier joined hundreds of protestors while a large number of the Gandhian’s supporters took out marches across the city.

Hazare refuses to leave jail, opposes time limit on fast

PTI STANDS FIRM: Social activist Anna Hazare continues his fast in the Tihar Jail in New Delhi on Wednesday.

Police agreeable to shifting venue to Ramlila Grounds, lift all but one condition

Faced with nationwide protests and slammed by a united Opposition in Parliament over the detention of social activist Anna Hazare, the government went into damage control mode on Wednesday, agreeing to lift all but one condition for the anti-corruption crusader's fast on the Lokpal Bill issue. The condition — restriction on the number of days of fast — remained a stumbling block to Mr. Hazare coming out of jail. Late in the evening a doctor visited him for a check-up, now that he had been on fast for almost two days.

Following daylong negotiations, the Delhi Police lifted the restriction on the number of protesters and cars, and allowed use of loudspeakers till 10 p.m. at the protest site. It also agreed to the shifting of the fast venue to the Ramlila Grounds that can accommodate huge numbers.

The police initially allowed a seven-day agitation, which was later extended to three weeks. This condition was rejected by Mr. Hazare and his team of negotiators, including Arvind Kejriwal, Prashant Bhushan, Swami Agnivesh, Kiran Bedi and Medha Patkar. Having declared an indefinite fast, Mr. Hazare wanted no time frame.

Team Anna is agitating for a revised, effective and comprehensive Lokpal Bill that will provide for setting up Lokayuktas in States, and cover the lower bureaucracy, the Prime Minister, the higher judiciary and public grievances to deal with day-to-day corruption.

“The huge outpouring of public support has made the government see sense in at least allowing the fast to be held at a larger venue. They have realised that the Jayaprakash Narayan Park cannot accommodate so many people and have agreed to shift the venue to the Ramlila Grounds,” Mr. Bhushan told The Hindu.

The damage control exercise began early in the day with Union Home Secretary R.K. Singh announcing that Mr. Hazare was free to go anywhere but he must discuss his fast programme with the Delhi Police. Since then there had been hourly reports of the activist coming out of jail but that did not happen.

The issue was discussed in both Houses after Prime Minister Manmohan Singh explained the government's point of view in a statement.

People of all hues thronged the gates of the Tihar jail that became an impromptu venue of the agitation. Baba Ramdev and Sri Sri Ravi Shankar visited Mr. Hazare in jail. They reported that he was continuing with his fast and was cheerful.

By evening, responding to a call by Team Anna, hundreds of people, predominantly students, marched from India Gate to Jantar Mantar here. Large-scale protests were reported from Mumbai, Bangalore, Secunderabad, Indore, Bhubaneswar and Chennai.

basic science: circular motion

Circular Motion


Rotation Vs. Revolution

Reasons for Seasons

Because the Earth is tilted on its internal axis, as the Earth rotates tropical areas (close to Equator) receive direct sun rays. If the northern hemisphere of the Earth is tilted away from the sun, then it will receive indirect sun rays and will be cooler.....winter.

As Earth, which is tilted about its internal axis of rotation, revolves around the Sun (external axis of revolution of the Earth) seasons are changed.

Reason for Seasons explained link: Science U Website

Velocity Vectors in Circular Motion

Acceleration in Circular Motion

An accelerating object is an object which is changing its velocity. And since velocity is a vector which has both magnitude and direction, a change in either the magnitude or the direction constitutes a change in the velocity.

An object moving in a circle at constant speed is indeed accelerating. It is accelerating because its velocity is changing its directions.

Acceleration in Circular Motion

Acceleration is the rate at which velocity changes. vi represents the initial velocity and vf represents the final velocity after some time of t. The numerator of the equation is found by subtracting one vector (vi) from a second vector (vf).

The addition and subtraction of vectors from each other is done in a manner much different than the addition and subtraction of scalar quantities. Consider the case of an object moving in a circle about point C as shown in the diagram below. In a time of t seconds, the object has moved from point A to point B. In this time, the velocity has changed from vi to vf. The process of subtracting vi from vf is shown in the vector diagram; this process yields the change in velocity.

Note in the diagram below that there is a velocity change for an object moving in a circle with a constant speed. Furthermore, note that this velocity change vector is directed towards the center. An object moving in a circle at a constant speed from A to B experiences a velocity change and therefore an acceleration; this acceleration is directed towards point C - the center of the circle.

Velocity & Acceleration Vectors in Circular Motion

For questions #1-#4: An object is moving in a clockwise direction around a circle at constant speed. Use your understanding of the concepts of velocity and acceleration to answer the next four questions. Use the diagram shown at the right.
1. Which vector below represents the direction of the velocity vector when the object is located at point B on the circle?
2. Which vector below represents the direction of the acceleration vector when the object is located at point C on the circle?
3. Which vector below represents the direction of the velocity vector when the object is located at point C on the circle?
4. Which vector below represents the direction of the acceleration vector when the object is located at point A on the circle?
5. Make up your own questions.

Circular Motion on a level surface: 3 forces

A car moving in a horizontal circle on a level surface experiences 3 forces.
Applying the concept of a centripetal force requirement, we know that the net force acting upon the object is directed inwards.
	Since the car is positioned on the left side of the circle, the net force is directed rightward. An analysis of the situation would reveal that there are three forces acting upon the object - the force of gravity (acting downwards), the normal force of the pavement (acting upwards), and the force of friction (acting inwards or rightwards).
It is the friction force which supplies the centripetal force requirement for the car to move in a horizontal circle.
Without friction, the car would turn its wheels but would not move in a circle (as is the case on an icy surface).

The centripetal force (acting inwards) is the force of friction between the tires and the road

Centripetal Force Requirement An object moving in a circle is experiencing an acceleration. Even if moving around the perimeter of the circle with a constant speed, there is still a change in velocity and subsequently an acceleration. This acceleration is directed towards the center of the circle. And in accord with Newton's second law of motion, an object which experiences an acceleration must also be experiencing a net force; and the direction of the net force is in the same direction as the acceleration. So for an object moving in a circle, there must be an inward force acting upon it in order to cause its inward acceleration. This is sometimes referred to as the centripetal force requirement. The word "centripetal" (not to be confused with the F-word "centrifugal") means center-seeking. For object's moving in circular motion, there is a net force acting towards the center which causes the object to seek the center.

Without Centripetal Force	With Centripetal Force
Without a centripetal force, an object in motion continues along a straight line path.	With a centripetal force, an object in motion will be accelerated and change its direction.

According to Newton's first law of motion, it is the natural tendency of all moving objects to continue in motion in the same direction that they are moving ... unless some form of unbalanced force acts upon the object to deviate the its motion from its straight-line path. Objects will tend to naturally travel in straight lines; an unbalanced force is required to cause it to turn. The presence of the unbalanced force is required for objects to move in circles......unbalanced force is called.....centripetal force.

"Feeling Acceleration"

A Car Starts From Rest: You are a passenger in a stopped car. The drive "hits the gas". You "feel" as if you are moving (accelerating) backwards into the car seat.

As the wheels of the car spin to generate a forward force upon the car to cause a forward acceleration, your body tends to stay in place (Newton's 1st Law). It certainly might seem to you as though your body were experiencing a backwards force causing it to accelerate backwards; yet you would have a difficult time identifying such a backwards force on your body. Indeed there isn't one. The feeling of being thrown backwards is merely the tendency of your body to resist the acceleration and to remain in its state of rest. The car is accelerating out from under your body, leaving you with the false feeling of being thrown backwards.

A Car Traveling At A Constant Velocity In A Straight Line: Constant Motion: The driver hits the brakes. You "feel" as if you are moving (accelerating) forwards towards the dashboard.

Your body being in motion tends to continue in motion while the car is slowing to a stop. It certainly might seem to you as though your body were experiencing a forwards force causing it to accelerate forwards; yet you would once more have a difficult time identifying such a forwards force on your body. Indeed there is no physical object accelerating you forwards. The feeling of being thrown forwards is merely the tendency of your body to resist the deceleration and to remain in its state of forward motion.

In both scenarios: the direction which the passengers lean is opposite the direction of the acceleration. This is merely the result of the passenger's inertia - the tendency to resist acceleration (change in motion). The passengers lean is not an acceleration in itself but rather the tendency to maintain whatever state of motion they have while the car does the acceleration.

Centripetal Force

You are a passenger in a car making a left-hand turn on an off ramp maintaining a constant speed.

During the turn, the car travels in a circular-type path. The unbalanced force acting upon the turned wheels of the car cause an unbalanced force upon the car and a subsequent acceleration. The unbalanced force and the acceleration are both directed towards the center of the circle about which the car is turning.

Your body is in motion and tends to stay in motion. It is the inertia of your body - the tendency to resist acceleration - which causes it to continue in its forward motion. While the car is accelerating inward, you continue in a straight line. If you are sitting on the passenger side of the car, then eventually the outside door of the car will hit you as the car turns inward.

This phenomenon might cause you to think that you were being accelerated outwards away from the center of the circle. In reality, you are continuing in your straight-line inertial path tangent to the circle while the car is accelerating out from under you. The sensation of an outward force and an outward acceleration is a false sensation. There is no physical object capable of pushing you outwards. You are merely experiencing the tendency of your body to continue in its path tangent to the circular path along which the car is turning.

Observe in the animation that the passenger (in blue) continues in a straight-line motion for a short period of time after the car begins to make its turn. In fact, the passenger follows a straight-line path until striking the shoulder of the driver (in red). Once striking the driver, a force is applied to the passenger to force the passenger to the right and thus complete the turn. An inward net force is required to make a turn in a circle. This inward net force requirement is known as a centripetal force requirement. In the absence of any net force, an object in motion (such as the passenger) continues in motion in a straight line at constant speed. This is Newton's first law of motion. While the car begins to make the turn, the passenger and the seat begin to edge rightward. As such, the car is beginning to slide out from under the passenger. Once striking the driver, the passenger can now turn with the car and experience some circle-like motion.

Centripetal Force Causes Circular Motion

As a car makes a turn, the force of friction acting upon the turned wheels of the car provide the centripetal force required for circular motion.	As a bucket of water is tied to a string and spun in a circle, the force of tension acting upon the bucket provides the centripetal force required for circular motion.	As the moon orbits the Earth, the force of gravity acting upon the moon provides the centripetal force required for circular motion.

Circular Motion Lab

Centripetal Force

Centripetal force keeps the planets in orbit. According to Newton’s 1st law, all masses have inertia and would like to move at constant speed in a straight line. Earth wants to move straight but it is prevented from doing so due to the sun’s gravity. The sun applies a centripetal force.

When you spin a bucket of water over your head without spilling a drop, you are also applying a centripetal force. If you let go of the bucket, it will move in a straight line.

Centripetal force pulls the plane toward the center of the circle. The plane’s inertia makes it want to fly straight.

While the coaster cars zoom around the loop, the track exerts a centripetal force toward the center of the loop.

If you whirl a ball attached to string around your head, it moves in a circular path around you because the string is always pulling the ball directly toward the hand grabbing the string. The ball wants to move in a straight line and the string is pulling it directly inward. The resulting deflection is a compromise: a circular path. The string is applying a centripetal force to the ball: an inward force. If you let go of the string, there is no centripetal force and the ball will fly off in a straight line because of its inertia.

Roller Coaster G-Forces from The Physics Classroom

A coaster rider is continuously altering her direction of motion while moving through the loop; at all times, the direction of motion could be described as being tangent to the loop. This change in direction is caused by the presence of unbalanced forces and results in an acceleration. Not only is there an acceleration, the magnitude and direction of the acceleration is continuously changing.

To understand the feelings of weightlessness and heaviness experienced while riding through a loop, it is important to think about the forces acting upon the riders.

The only forces exerted upon the riders are the force of gravity and the normal force (the force of the seat pushing up on the rider). The force of gravity is at all times directed downwards and the normal force is at all times directed perpendicular to the seat of the car. Since the orientation of the car on the track is continuously changing, the normal force is continously changing its direction. The magnitude and direction of these two forces during the motion through the loop are depicted in the animation below.

In order for an object to move through a circle, it is necessary that there be a net inward force acting upon the rider. This is commonly referred to as the centripetal force requirement. Thus, the net force acting upon the rider is always directed inwards (towards the center of the circle). Since the net force is the vector sum of all the forces, the head-to-tail addition of the normal force and the gravity force should sum to a resultant force which is directed inward.

The diagram below depicts the free-body diagrams for a rider at four locations along the loop. The diagram also shows that the vector sum of the two forces (i.e., the net force) points towards the center of the loop for each of the locations.

Feelings of weightlessness and heaviness are associated with the normal force; they have little to do with the force of gravity. A person who feels weightless has not lost weight; the force of gravity acting upon the person is the same magnitude as it always is. Witness in the animation above that the force of gravity is everywhere the same. The normal force however has a small magnitude at the top of the loop (where the rider often feels weightless) and a large magnitude at the bottom of the loop (where the rider often feels heavy). The normal force is large at the bottom of the loop because in order for the net force to be directed inward, the normal force must be greater than the outward gravity force. At the top of the loop, the gravity force is directed inward and thus, there is no need for a large normal force in order to sustain the circular motion. The fact that a rider experiences a large force exerted by the seat upon her body when at the bottom of the loop is the explanation of why she feels heavy.

crank shaft balancing

 

 

 

 

 

 

 

Forces In Action

To better understand the mechanics of balancing, let’s look at the theory behind it. As everybody knows, a rotating object generates "centripetal force." Centripetal force is an actual force or load generated perpendicular to the direction of rotation. Tie a rope to a brick and twirl it around and you’ll feel the pull of centripetal force generated by the "unbalanced" weight of the brick. The faster you spin it, the harder it pulls. In fact, the magnitude of the force increases exponentially with speed. Double the speed and you quadruple the force.

The centripetal force created by a crankshaft imbalance will depend upon the amount of imbalance and distance from the axis of rotation (which is expressed in units of grams, ounces or ounce-inches). A crankshaft with only two ounce-inches of imbalance at 2,000 rpm will be subjected to a force of 14.2 lbs. At 4,000 rpm, the force grows to 56.8 lbs.! Double the speed again to 8,000 rpm and the force becomes 227.2 lbs.

This may not sound like much when you consider the torque loads placed upon the crankshaft by the forces of combustion. But centripetal imbalance is not torque twisting the crank. It is a sideways deflection force that tries to bend the crank with every revolution. Depending on the magnitude of the force, the back and forth flexing can eventually pound out the main bearings or induce stress cracks that can cause the crank to snap.

Centripetal force should not be confused with "centrifugal" force, which is the tendency of an object to continue in a straight trajectory when released while rotating. Let go of the rope while you’re twirling the brick and the brick will fly off in a straight line (we don’t recommend trying this because its difficult to control the trajectory of the brick).

Back to centripetal force. As long as the amount of centripetal force is offset by an equal force in the opposite direction, an object will rotate with no vibration. Tie a brick on each end of a yardstick and you can twirl it like a baton because the weight of one brick balances the other. If we’re talking about a flywheel, the flywheel will spin without wobbling as long as the weight is evenly distributed about the circumference. A heavy spot at any one point, however, will create a vibration because there’s no offsetting weight to balance out the centripetal force.

This brings us to another law of physics. Every object wants to rotate about its own center of gravity. Toss a chunk of irregular shaped metal into the air while giving it a spin and it will automatically rotate about its exact center of gravity. If the chunk of metal happens to be a flywheel, the center of gravity should be the the flywheel’s axis. As long as the center of gravity for the flywheel and the center of rotation on the crankshaft coincide, the flywheel will spin without vibrating.

But if there’s a heavy spot on the flywheel, or if the flywheel isn’t mounted dead center on the crank, the center of gravity and axis of rotation will be misaligned and the resulting imbalance will create a vibration.

Applied Physics

Okay, so how does all this scientific mumbo jumbo translate into the real world dynamics of a spinning crankshaft? A crankshaft, like a flywheel, is a heavy rotating object. What’s more, it also has a bunch of piston and rod assemblies reciprocating back and forth along its axis that greatly complicate the problem of keeping everything in balance.

With inline four and six cylinder engines, and flat horizontally opposed fours and sixes (like Porsche and Subaru), all pistons move back and forth in the same plane and are typically phased 180° apart so crankshaft counterweights are not needed to balance the reciprocating components. Balance can be achieved by carefully weighing all the pistons, rods, wrist pins, rings and bearings, then equalizing them to the lightest weight.

On V6, V8, V10 and V12 engines, it’s a different story because the pistons are moving in different planes. This requires crankshaft counterweights to offset the reciprocating weight of the pistons, rings, wrist pins and upper half of the connecting rods.

With "internally balanced" engines, the counterweights themselves handle the job of offsetting the reciprocating mass of the pistons and rods. "Externally balanced" engines, on the other hand, have additional counterweights on the flywheel and/or harmonic damper to assist the crankshaft in maintaining balance. Some engines have to be externally balanced because there isn’t enough clearance inside the crankcase to handle counterweights of sufficient size to balance the engine. This is true of engines with longer strokes and/or large displacements.

If you’re rebuilding an engine that is internally balanced, the flywheel and damper have no effect on engine balance and can be balanced separately. But with externally balanced engines, the flywheel and damper must be mounted on the crank prior to balancing.

Customers should be told what type of engine balance they have (internal or external), and warned about indexing the position of the flywheel if they have to remove it later for resurfacing. Owners of externally balanced engines should also be warned about installing different flywheels or harmonic dampers and how it can upset balance.

Balance Shafts

In recent years, the auto makers have added balance shafts to many four and six cylinder engines to help cancel out crankshaft harmonics. The counter-rotating balance shaft helps offset vibrations in the crank created by the firing sequence of the engine.

On these motors, make sure the balance shaft is correctly "phased" or timed to the rotation of the crank. If the shaft is out of sync, it will amplify rather than diminish engine vibrations.

Balance shafts are not a substitute for normal engine balancing, nor do they reduce the vibration and stress the crankshaft itself experiences as it turns.

Balancing Act

The process of balancing begins by equalizing the reciprocating mass in each of the engine’s cylinders. This is done by weighing each piston on a sensitive digital scale to determine the lightest one in a set. The other pistons are then lightened to match that weight by milling or grinding metal off a non-stressed area such as the wrist pin boss. The degree of precision to which the pistons are balanced will vary from one engine builder to another, and depends to some extent on the application. But generally speaking pistons are balanced to within plus or minus 0.5 grams of one another.

Next the rods are weighed, but only one end at a time. A special support is used so that the big ends of all the rods can be weighed and compared, then the little ends. As with the pistons, weights are equalized by grinding away metal to within 0.5 grams. It’s important to note that the direction of grinding is important. Rods should always be ground in a direction perpendicular to the crankshaft and wrist pin, never parallel. If the grinding scratches are parallel to the crank, they may concentrate stress causing hairline cracks to form.

On V6 and V8 engines, the 60 or 90 degree angle between the cylinder banks requires the use of "bobweights" on the rod journals to simulate the reciprocating mass of the piston and rod assemblies. Inline four and six cylinder crankshafts do not require bobweights. To determine the correct weight for the bobweights, the full weight of a pair of rod bearings and the big end of the connecting rod, plus half the weight of the little end of the rod, piston, rings, wrist pin (and locks if full floating) plus a little oil are added together (100 percent of the rotating weight plus 50 percent of the reciprocating weight). The correct bobweights are then assembled and mounted on the crankshaft rod journals.

The crankshaft is then placed on the balancer and spun to determine the points where metal needs to be added or removed. The balancer indexes the crank and shows the exact position and weight to be added or subtracted. The electronic brain inside the balancer head does the calculations and displays the results. The latest machines have graphical displays that make it easy to see exactly where the corrections are needed.

If the crank is heavy, metal is removed by drilling or grinding the counterweights. Drilling is usually the preferred means of lightening counterweights, and a balancer that allows the crank to be drilled while still on the machine can be a real time saver.

If the crank is too light, which is usually the case on engines with stroker cranks or those that are being converted from externally balanced to internally balanced, heavy metal (a tungsten alloy that is 1.5 times as heavy as lead) is added to the counterweights. This is usually done by drilling the counterweights, then press fitting and welding the heavy metal plugs in place. An alternate technique is to tap the hole and thread a plug into place. Drilling the holes sideways through the counterweights parallel to the crank rather than perpendicular to the crank is a technique many prefer because it prevents the metal from being flung out at high rpm.

After drilling, the crankshaft is again spun on the balancer to determine if additional corrections are required. If the crank is for an externally balanced engine (such as a big block Chevy), the balancing will be done with the flywheel and damper installed. On internally balanced engines, the flywheel and damper can be balanced separately, or installed on the crank and balanced as an assembly once the crank itself has been balanced.