A harmonic damper is a device fitted to the free (accessory drive) end of the crankshaft of an enclosed combustion engine to counter torsional and resonance vibrations from the crankshaft. This device must be interference suitable for the crankshaft to work effectively. An interference fit ensures the device moves in perfect step with the crankshaft. It’s essential on engines with long crankshafts (such as straight-6, straight-8 engines) and V8 engines with cross-plane cranks. Harmonics and torsional vibrations can greatly reduce crankshaft life, or cause instantaneous failure if the crankshaft runs at or through an amplified resonance. Dampers are designed with a particular weight (mass) and diameter, which are addicted to the damping material/method used, to scale back mechanical Q factor, or damp, crankshaft resonances.
A harmonic balancer (sometimes crankshaft damper, torsional damper, or vibration damper) is that the same thing as a harmonic damper except that the balancer includes a counterweight to externally balance the rotating assembly. The harmonic balancer often is a pulley for the accessory drive belts turning the alternator, water pump, and other crankshaft-driven devices.
Why do we need a Harmonic Damper?
Need of Harmonic Damper:
The need for a damper will rely on the age of the engine design, its manufacture, strength of components, usable powerband, rev range, and, most significantly, the standard of the engine’s tune. The engine’s tune especially in computer-controlled applications can have a dramatic effect on durability, the aggressiveness of the tune puts the engine in danger of detonation which may be catastrophic to all or any rotating assembly components.
Modern (roughly 1988+) DOHC, SOHC flat 4, I4, flat 6, I6, V6, flat 8, and flat-plane V8 don’t need this device. With or without the presence of a damper, a crankshaft will act as a torsional spring to some extent. Impulses applied to the crankshaft by the connecting rods will “wind” this spring, which can respond (as a spring-mass system) by unwinding and re-winding in the wrong way. This crankshaft winding will usually be damped out naturally.
However, at certain crankshaft rotational speeds, such winding can overlap with the crankshaft’s natural resonant frequency, thereby increasing the frequency’s amplitude and possibly resulting in crankshaft damage.
What does a harmonic balancer do?
Harmonic Balancer Does This:
A harmonic balancer feels like an important part of a spaceship in some pulpy 1950s sci-fi story, or something you wish so you’ll be able to play music with hobos when you’re ridin’ the rails. However, it’s a crucial part of your engine that helps your crankshaft last as long as possible.
As the cylinders in your engine fire, they move up and down, generating torque that’s transferred into the crankshaft. As you’ll already know, the crankshaft is what converts the engine’s power into rotational movement, eventually turning the wheels of the car.
But consider for a second the forces that are engaged on the crankshaft — they’re tremendous. On every occasion a cylinder fires, a force acts upon the crankshaft, causing it to twist. But this force also causes vibrations in the crankshaft, and at certain frequencies, the shaft can resonate, which makes the vibrations even worse.
These vibrations from the engine can become an excessive amount for the crankshaft, in reality, causing it to fail. And when that happens, your car won’t run and you may be facing some expensive repairs.
This is where the harmonic balancer comes in. The circular device, manufactured from rubber and metal, is bolted at the side of the crankshaft to assist absorb vibrations. It has always connected to the crank pulley, which drives accessories just like the cooling system. The rubber inside the pulley is what absorbs the vibrations and keeps them at a secure level. In essence, the device is meant to assist prevent crankshaft failure. It is also sometimes called a “dampener.”
However, the rubber material can deteriorate over time. So if your harmonic balancer goes bad, you may get rough engine vibrations, a cracked crankshaft, or maybe a serpentine belt that gets thrown off its track. Replacing one is great preventative maintenance, and that is exactly what we’ll speak about next.
How do I replace my Harmonic Balancer?
Replacing Harmonic Balancer:
So you would like to interchange your harmonic balancer, huh? There’s excellent news and bad news. First, the great news: Installing a brand new balancer is a relatively easy task. And now the bad news: Getting the old one off the crankshaft isn’t. It could involve the mutilation of a number of your car’s body parts, just like the front fender or bumper, and possibly even the radiator.
Every engine is different, so if you wish to alter the harmonic balancer on your car, you will need to go looking around various car forums and internet sites to determine how it’s done on your specific model. Generally, you will need to get rid of the belt from the crankshaft pulley so take the harmonic balancer mounting bolt off with a socket and ratchet. From there, you’ll use the puller tool you only bought to require the balancer itself off the crankshaft.
As far as reinstalling the new harmonic balancer goes, it’s just about the identical steps in reverse. Just make certain to match the old part and also the new part to create sure the bolt hole locations are identical. And do not forget to pay close attention to the right torque settings, too. If you’ll be able to start your engine and also the vibrations don’t jar your tooth fillings loose, you’ve done the work correctly.
First, you’ll likely have to venture out and buy a tool you may not have — a harmonic balancer puller. That’s a specialized tool that’s wont to safely remove harmonic balancers without damaging your vehicle, and it also works on things like gear pulleys and steering wheels. Search around to search out the proper puller for your needs. They’re usually around $25 roughly.
What are the Symptoms of a Bad or Failing Harmonic Balancer?
Symptoms of a Bad or Failing Harmonic Balancer:
The crankshaft harmonic balancer is a device connected to the front of an engine’s crankshaft, usually built into the crankshaft pulley. Its purpose is to soak up and reduce harmonic vibrations from the engine because the crankshaft rotates, as harmonic vibrations at high engine speeds can cause accelerated wear and damage to the components. they’re usually made from rubber and metal, which easily absorbs any harmonic vibrations that would harm the engine otherwise. Usually, an issue with the harmonic balancer will produce some symptoms that may alert the motive force of a possible problem that ought to be serviced.
One of the primary symptoms of a possible problem with the harmonic balancer is engine vibration. The harmonic balancer is specifically designed to soak up harmonic engine vibrations as engine speeds rise. If the harmonic balancer gets too old or fails and may now not properly absorb the harmonic vibrations, the engine will shake excessively. The shaking will become even more pronounced, and so dangerous to the engine at high speeds.
Misaligned timing marks:
Another symptom of a possible problem with the harmonic balancer is misaligned timing marks. The harmonic balancers found on many vehicles are constructed as two pieces of metal with a rubber layer in between to dampen the vibrations. If the layers separate or slip, the timing marks, which are usually stamped into the front of the pulley, can shift and thus throw off the position of the timing marks. This can make it difficult, if not impossible to properly time the engine with a timing light.
Separated harmonic balancer:
Another more serious symptom of a controversy with the harmonic balancer could be a separated harmonic balancer. If the rubber layer within the harmonic balancer dries or wears out, it can cause the whole harmonic balancer to completely fail by separating. If the harmonic balancer separates, the engine belts will usually come off and therefore the vehicle is going to be left without engine accessories.
What Happens When a Harmonic Balancer Fails?
When a Harmonic Balancer Fails:
Although the harmonic balancer could seem simple enough, if it fails, it can cause major problems. Without the balancer dampening unwanted crankshaft vibrations, engine failures, like worn rod bearings and a broken crankshaft, may result.
A faulty balancer can damage the belt and engine-driven accessories likewise. It’s also possible for the balancer to fly apart, leading to the destruction of a range of underhood components.
Without a doubt, you must always replace a faulty harmonic balancer straight away.
What is Centrifugal Pendulum Absorber and its Functions?
Centrifugal Pendulum Absorber:
A centrifugal pendulum absorber is a form of a Tuned mass damper. It reduces the amplitude of a Torsional vibration in drive trains that use a combustion engine.
The centrifugal pendulum absorber was first patented in 1937 by R. Sarazin and a special version by R. Chilton in 1938. Generally, both Sarazin and Chilton are credited with the invention. Sarazin’s work was used during war II by Pratt & Whitney for aircraft engines with increased power output. The ability increase caused a rise in torsional vibrations which threatened the sturdiness. This resulted in the Pratt & Whitney R-2800 engine that used pendulum weights attached to the crankshaft.
The use of centrifugal pendulum absorbers in land vehicles didn’t start until later. Although burning engines had always caused torsional vibrations within the drive train, the vibration amplitude was generally not high enough to affect durability or driver comfort. One application existed in tuned racing engines where torsional crankshaft vibrations could cause damage to the camshaft or valves. During this application, a centrifugal pendulum absorber, the Rattler absorber, is directly attached to the crankshaft. Although the planning differs from that of Sarazin or Chilton, the Rattler still follows the identical physical principle.
The function of a centrifugal pendulum absorber is like any tuned mass absorbers supported an absorption principle instead of a damping principle. Excellence is critical since dampers reduce the vibration amplitude by converting the vibration energy into heat. Absorbers store the energy and return it to the vibration system at an acceptable time. Centrifugal pendulum absorbers like tuned mass absorbers don’t seem to be a part of the force/torque flow.
The centrifugal pendulum absorber differs from the tuned mass absorber within the absorption range. It’s effective for a whole order rather than a narrow frequency range.
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