Terminology problem - meaning of neutrally balanced - Page 4 - PeachParts Mercedes-Benz Forum

97 SL320 · #46 01-26-2012, 07:23 PM

"" Brian Carlton

A few points need to be corrected above.

There are two types of unbalance. "Static" and "Couple". Static unbalance is the unbalance generated at the CG of a component and is corrected with a single correction weight, preferably placed at the CG. ""

In order for a balance correction weight to do anything, it must be away from the CG because, the imbalance is being caused by unevenly distributed mass away from the CG. Please demonstrate how adding mass to my example will correct for the coins.

"" To fully correct dynamic unbalance requires the addition of weights in two separate (as far as possible) correction planes. ""

For the most part this matches the 2nd part of my example.

"" The more costly machines for this purpose do not utilize any stroboscopic pickup for angle reference and rely on a probe or a photocell to determine zero degrees. The balancing machine instrument then measures the difference in angle between the peak force and the zero degree position of the rotor. ""

Nothing new here, this was discussed in my example.

"" BTW, there is no term "imbalance". The proper term is "unbalance". ""

Gee, you are right, I found this link to support your claim.
Performance Tire Balancing | Yokohama Tire Corp.

whunter · #47 01-26-2012, 07:45 PM

Quote:

Originally Posted by Army

SAE standards are great as are standards set by the society of this or the institute of that...

The problem is that they are not made publicly available. These organizations are mostly exclusive organizations - we here, however, are inclusive. We don't charge money for our knowledge we give it freely to help each other out.

If "we" choose to go along with the same convention as the SAE then that's fine by me. We could have, however, just have easily decided to (do a rather silly thing and) make reference to every point on the car with reference to the position of Mecca!

Don't forget we are free men with a few free women here...

That was only for your information.
I try to avoid confusion.
Here is further data you may find interesting.

This is the standard for automotive mechanics in the US.
It is the only standard accepted by the US government.
Basic automotive training includes SAE orientation training, because test questions are written by a constantly changing group of SAE engineers drawn from most automotive manufacturers that sell/import to the US, and a few that want to.
Here are the study guides.
ASE - Download the Guides

Left and Right orientation/definition.

The reason for this definition is:
There is no other simple logical consistent basic orientation across the world for truck, bus, and car.

I am sad to inform you that at the time SAE implemented this convention, a shocking number of mechanics world wide had failed to complete primary education = rated as semiliterate.
Unfortunately the percentages are still extremely embarrassing.

.

Stretch · #48 01-27-2012, 02:42 AM

Quote:

Originally Posted by tangofox007

Here is what I do not understand:

A person will stand at the front of the car, facing aft, and, all of a sudden, left magically becomes right and right turns into left. If, however, you were to suggest to that person that the headlights just turned into tail lights, they would think you were off your rocker.

If one insists on engaging in asinine practices, at least be consistent about it.

Yep - we still talk about the engine turning clockwise - or never turn an OM617 anti-clockwise etc

Stretch · #49 01-27-2012, 02:48 AM

Quote:

Originally Posted by whunter

...
I am sad to inform you that at the time SAE implemented this convention, a shocking number of mechanics world wide had failed to complete primary education = rated as semiliterate.
Unfortunately the percentages are still extremely embarrassing.

.

Indeed - but these days the trend is to use the unskilled becasue they are cheap to employ - the computer tells you which huge and expensive car part to replace...

It is a sorry state of affairs - no relatively inteligent but poorly educated worker is going to get satisfaction from fault diagnosis like that. This approach to maintenance in my opinion just leads to poor customer service.

panZZer · #50 01-27-2012, 05:39 PM

Quote:

Originally Posted by t walgamuth

v6's with sixty degree angle are naturally balanced. if they are nintey degrees you are correct about needing shafts.

any flat engine is naturally balanced.

v12's with sixty degrees are naturally balanced too.

4.3 chevys --90 degree--do not have counterbalancing shafts--and they are pretty damn good engines. the 2.8 60 degree ones have always been considered pieces of excretement.

t walgamuth · #51 01-27-2012, 05:48 PM

We're not discussing quality or longivity just whether they have naturally "balanced" power pulses.

Brian Carlton · #52 01-27-2012, 06:26 PM

Quote:

Originally Posted by 97 SL320

In order for a balance correction weight to do anything, it must be away from the CG because, the imbalance is being caused by unevenly distributed mass away from the CG. Please demonstrate how adding mass to my example will correct for the coins.

Your making some generalizations without stating the type of unbalance. Your statement is true for couple unbalance...........false for static unbalance.

Quote:

Originally Posted by 97 SL320

Gee, you are right, I found this link to support your claim.

Gee, you think?

I've only been balancing jet engines for 25 years...........I might know as much a tire manufacturer.

tangofox007 · #53 01-27-2012, 07:30 PM

Quote:

Originally Posted by Army

Yep - we still talk about the engine turning clockwise - or never turn an OM617 anti-clockwise etc

We???
By SAE convention, anti-clockwise is precisely the way a 617 normally turns.

97 SL320 · #54 01-27-2012, 08:30 PM

" " Gee, you think?

I've only been balancing jet engines for 25 years...........I might know as much a tire manufacturer. ""

I guess you didn't click and read my link. . . . .Check . . .

. . . . And Check mate. . .

"" Better to keep your mouth shut and be thought a fool than to open it and remove all doubt ----- Mark Twain ""

Text from my link.

Balancing

The technical definition of balance is the uniform distribution of mass about an axis of rotation, where the center of gravity is in the same location as the center of rotation. A balanced tire is one where the mass of the tire when mounted on its wheel and the car's axle is uniformly distributed around the axle (its center of rotation). Balanced tires can spell the difference between a positive and negative driving experience. Drivers of high performance vehicles will be more sensitive to imbalance problems, but no driver is happy with an annoying vibration.

An Out-Of-Balance Tire And Wheel Assembly:

Sources of Imbalance
For the proper mounting of Yokohama tires, be sure to observe some basic precautions:

Degrades ride quality and driver comfort.
Shortens the life of tires, bearings, shock absorbers and other suspension components. Vibration is the most noticeable effect of imbalance. It is dependent on vehicle speed.
It often first becomes apparent between 40 and 45 mph and increases in magnitude with greater speeds.

Two sources of imbalance occur in tires:
heavy or light spots in the tire and radial or lateral run-out. Imbalance also can be caused by:

Variations within the wheel, such as thickness and welds.
Rotor and axle imbalances.

Heavy or Light Spot Imbalance

Heavy or Light Spot Balancing
There are two types of imbalance caused by heavy or light spots: static and dynamic.

Static imbalance:

Occurs when there is a heavy or light spot in the tire so that the tire won't roll evenly and the tire/wheel assembly undergoes an up-and-down movement.

Dynamic imbalance:

Occurs when there is unequal weight on both sides of the tire/wheel assembly enterline. The tire/wheel assembly has a side-to-side movement.
Achieved either statically or dynamically, depending on the type of imbalance that has occurred.

Static balance: Achieved with a bubble balancer but does not correct for dynamic imbalance.
Dynamic balance: Achieved with a spin balancer where the tire/wheel assembly is balanced both statically and dynamically.

Radial or Lateral Run-out Imbalance Run-out Balancing
This results from poor bead seating on the rim or the placement of components. Poor bead seating is usually the result of improper mounting or the use of improperly made wheels. A small degree of this imbalance is acceptable, but too great a run-out causes vibration and excessive tire wear.

Radial Run-out:

An "out-of-round" situation where vibrations are produced as the wheel spindle moves up and down.

Lateral Run-out:

A side-to-side or wobbling movement of the tire and wheel. It is less common than radial run-out. Sensitivity of a vehicle to vibration from radial run-out is four to eight times that of wobble from lateral run-out.
Depends on whether it is radial or lateral run-out.

Radial run-out balancing:

Achieved by rotating the wheel and tire assembly two stud positions on the hub, or by rotating the tire 180¡ on the wheel. If run-out is still over specification, check wheel run-out and mark the low point. Rotate to match the high point of the assembly run-out with the wheel low point. If the assembly run-out is still too high and the wheel is within specification, replace the tire.

Lateral run-out:

Achieved by using a run-out gauge to check both the tire and wheel. Chalk-mark the highest point of run-out on both the wheel and tire. Replace whichever (wheel, tire, or both) is out of specification

Brian Carlton · #55 01-27-2012, 10:45 PM

Quote:

Originally Posted by 97 SL320

I guess you didn't click and read my link. . . . .Check . . .

About the only thing you got right in the entire thread.

You did a cut and paste from people that know just a tad more than you do...........and they have a multitude of errors in their statements.

vstech · #56 01-28-2012, 07:29 PM

Quote:

Originally Posted by panZZer

4.3 chevys --90 degree--do not have counterbalancing shafts--and they are pretty damn good engines. the 2.8 60 degree ones have always been considered pieces of excretement.

the first generation 4.3's do not have balance shafts, but the newer ones do.

and afaik, the 2.8's only flaw is it's wimpyness. it's likely a very smooth running engine.

Diesel911 · #57 08-15-2012, 08:44 AM

Quote:

Originally Posted by 47dodge

the crank is normally checked for balance when spinning with "bob" wieghts to simulate a portion of the weight of the rods and pistons, and a strobe light. My crank balanced to within one gram on my 240d.

The flywheel is normally balanced statically as per fsm instructions. This is between two shafts with presision ball bearings. When the flywheel does not roll to any one point it is balanced. This all assumes what Tom has said and that the crank can be balanced without needing additional weight

Static Balancing is one method of balancing.

You can put a Flywheel on a Dynamic Balancing Machine and spin it as they do on Tires.

Either method can result in a Neutral Balance.

I think here in the US when an average Person is speaking of something being balanced that spins that are speaking Neutral Balance.

Diesel911 · #58 08-15-2012, 08:59 AM

Quote:

Originally Posted by Army

Yep - we still talk about the engine turning clockwise - or never turn an OM617 anti-clockwise etc

Army we speak a dialect of English here in the US.

Anticlockwise=counter clockwise
All in= all out
Bonnet= a type of Hat for Women
Spanner= is a special type of Wrench here

A funny one: "knocked up" in the US means to get someone pregnant or If I was in the UK and a Women was to say "Come knock me up sometime"; it would not mean what I would think it would mean; but simply to come and visit Her.
And, so on.

Is this thread worse than an Oil Thread?

Stretch · #59 08-15-2012, 09:26 AM

Quote:

Originally Posted by Diesel911

Army we speak a dialect of English here in the US.

Anticlockwise=counter clockwise
All in= all out
Bonnet= a type of Hat for Women
Spanner= is a special type of Wrench here

A funny one: "knocked up" in the US means to get someone pregnant or If I was in the UK and a Women was to say "Come knock me up sometime"; it would not mean what I would think it would mean; but simply to come and visit Her.
And, so on.

Is this thread worse than an Oil Thread?

The best one you missed out is "I could do with a fag"!

As far as I am aware being knocked up is the same as the US version now.

I often talk about wings whilst most people here talk about fenders though I get the impression that sometimes fender can also mean bumper...

...is this thread worse than an oil thread? I don't know - it could be - from now on let's keep on talking off topic stuff instead!