Wheel Alignment: Compensation, Offset, Caster

Hi there.
Can anyone explain to me how the wheel imbalance compensation feature works on the VAG 1813 axle alignment system (manufactured by Beissbarth)?
Observation on the test stand: The vehicle is stationary on its wheels, and the mechanic is guided through a menu, wheel by wheel. He adjusts only the control on the measuring device attached to each wheel until 4 indicators per wheel turn green.
hg
Herbert.

I can only imagine that the distance to the rim (in the area of the bolt circle) is measured at a minimum of 3 points using sensors in order to determine the "zero point."

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The vehicle is stationary on its wheels, and the mechanic is guided through a menu, wheel by wheel, and only adjusts the setting on the measuring device attached to each wheel until 4 indicators per wheel turn green.

Okay, I don't have the 1813 model in front of me right now, but usually, the wheel is spun in the air!
If someone is too lazy or knows that the rim is bent, they might simply adjust the reading on the measurement device.

Of course, nothing is being compensated in that way.

although...

"Quote from Beissbarth:"

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VAG 1813 Radio - VAG 1995 Cable: Now with automated rim runout compensation

Perhaps they've come up with something new... I can't find any information quickly about what "automated rim impact compensation" means.
The device looks like the standard model.

Thank you -

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...but normally the wheel is rotated in the air!...

That's what I would have expected, unless there is an optical scanning of the rim.
hg
Herbert.

To conclude, I would like to summarize the results of my research and observations.
- When performed correctly, the rim runout compensation is carried out with the wheels raised, and each wheel is rotated through four positions. The measurement computer calculates the rim runout, including the tensioning device, based on deviations in the optical readings. The calculated compensation value is then displayed. If the value exceeds 50, the computer will not accept the compensation. If you are familiar with the condition of your wheels (e.g., after installing new tires), you may notice the first signs of an error during the measurement process. High values with good roundness can be attributed to installation errors in the tensioning device or a defect in the measurement head.
If things need to be done quickly, the mechanic uses pliers on the measuring head (probably the rotary angle sensor) and, of course, gets zero wheel imbalance.
- To measure toe and camber, the service brake must be locked in place. The calibrated sensors register the wheel rotation when the steering is turned +/- 20 degrees. The measurement computer then calculates the toe and camber based on this data. If the wheel can roll, it creates a counter-rotation, and especially the toe values will be measured too low. This is often not understood (...we've never done it before...), but the "aha" moment comes when the measurement with locked wheels yields different results.
I have changed the title to match the summary.
Sure, here's the translation:

"Best regards," or "Sincerely,".
Herbert.

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- When performed correctly, the rim runout compensation is carried out on raised wheels, and each individual wheel is rotated through four positions.

Just to be on the safe side, so you don't jump to conclusions and blame the mechanic right away:

In the meantime, there are Beissbarth Easy 3D test stands (see YouTube) that allow measurements to be taken "without lifting" the vehicle. With these systems, after the measurement heads are attached, the entire vehicle is moved forward and backward.

There are also devices that are clamped directly to the wheel hub via the rim. In these cases, the runout compensation may not be necessary.

Possible future applications: Sensors could measure the distance, for example, to the hub/brake disc.
And I thought that would already be a reality .

P.S.: It's impossible to adjust the measurement heads to simulate a rotating wheel for the computer. People who do things like that should be fired.

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In the meantime, there are Beissbarth Easy 3D test stands (see YouTube), where the measurement can be done "without lifting" the vehicle.

With these systems, after the measurement heads are installed, the entire vehicle is moved forward and backward.

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For this, the vehicle must roll for at least one full wheel revolution. I am not referring to such a test stand. Typically, workshops have stationary axle alignment systems.

Then there are also devices that are clamped directly to the wheel hub via the rim. In these cases, the run-out compensation may be omitted.

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Nein. Damit wird weder ein Schlag der Nabe erkannt, noch ungleiche Haltekrallen, noch ein Montagefehler. Abgesehen davon, daß die Nabe in der Bremsscheibe steckt, nach einigen Betriebsjahren sind Nabe und Scheibe rostig und uneben. What then? The only clean method is to center it on the axis of rotation.

For the future, it is conceivable that sensors could measure the distance, for example, to the hub/brake disc.
And I thought that would already be a reality

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. Yes? And what happens if there is a delay?

P.S.: It's impossible to adjust the measurement heads to make the computer believe it's seeing a rotating wheel. } People who do that should be fired. Just saying.
hg
Herbert.

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Quote: In the meantime, there are Beissbarth Easy 3D test stands (see YouTube), where the measurement can be done "without lifting" the vehicle. Quote: With these systems, after the measurement heads are installed, the entire vehicle is moved forward and backward. For this, the vehicle must roll for at least one full wheel rotation. I am not referring to a measurement taken from such a setup. Typically, workshops have stationary axle measurement stands.

Like the modified post title, this is intended for the general public and for the sake of completeness, and not specifically for this particular measurement, in order to avoid misunderstandings between the workshop and the customer.

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Quote: Then there are also devices that are clamped directly to the wheel hub via the rim. In these cases, the runout compensation can be omitted. Quote: Nein. Damit wird weder ein Schlag der Nabe erkannt, noch ungleiche Haltekrallen, noch ein Montagefehler. Abgesehen davon, daß die Nabe in der Bremsscheibe steckt, nach einigen Betriebsjahren sind Nabe und Scheibe rostig und uneben. What then? The only clean method is to center it on the axis of rotation.

However (unfortunately), that is the case, although I personally don't think much of it.

Are you looking at "just for example" here: http://www.eichstaedt-elektronik.de/kfz_werkstatt/eingestellte_achsmessgeraete/ccd_2800_www.pdf

and here: http://www.kfztech.de/kfztechnik/fahrwerk/achsvermessung/achsvermessung2.htm

http://www.beissbarth.com/Center/pdf/Docs/OEM%20MB%20Sammelprospekt%20DE%202009%2005%2014.pdf

The rest can be found in the respective regional legal framework.

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Quote: In the meantime, there are Beissbarth Easy 3D test stands (see YouTube), where the measurement can be done "without lifting" the vehicle.

With these systems, after the measurement heads are mounted, the entire vehicle is moved forward and backward.

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For this, the vehicle must roll for at least one full wheel revolution. I am not referring to a measurement taken from such a setup. Typically, workshops have stationary axle measurement stands. }

"With our Hunter Hawkeye, the vehicle needs to be moved back about a quarter of a wheel revolution and then forward... and that's enough."
It couldn't be any closer, because otherwise the (horizontally mounted) brackets for the sensors would get pinched between the tire and the lifting platform.

Hello there,
All the devices you mentioned measure rim runout or misalignment of the measurement heads based on wheel rotation. Beissbart does this using only the measurement heads, which is why the wheel or axle needs to be lifted. Hawkeye uses external cameras.
The accuracy of the measurement likely also depends on the range of rotational angles of the wheel being measured, but that might be a purely academic point.
What surprises me about the Hawkeye measurement is that the turntable is lowered to compensate for something???
I'm not bringing this whole thing up in the forum for no reason ( https://community.dieselschrauber.org/en/viewtopic.php?t=26520 ). The rim runout compensation was strange, and the expansion values were garbage because the brake wasn't properly checked.
A subsequent measurement, performed as a courtesy on the same vehicle two months later, revealed a nearly uncompensable wheel imbalance of 50' on the front right wheel, and a camber angle that was out of specification by a similar amount. The only change was the installation of new tires, which are running perfectly on the balancing machine and on the vehicle. When measured with a spirit level, both wheels have a camber of approximately 40'.
The spread values changed remarkably from approximately 2° to approximately 12° between the initial and final measurements, as predicted by the geometry, after I instructed the application of the brake.
Conclusion: The measurement principle was not understood, and the measurement head is crooked on the right front.
hg
Herbert.