Point of mechanical engineering "balance"

[Lionelgee]

Hello All,

What is the point of balance called when something round and dynamic - such as a car tyre, is put into a "balancing machine" and weights are added to it until it is "balanced". Or in the case of a flywheel metal is removed until the fly wheel is balanced or runs "true". Other than "balanced" or "True" what is the term used in mechanical engineering parlance?

Is it the point of equilibrium? Or is it known by another name? For instance, in the example of a balance beam with two uneven weights located at opposing ends - a pivot can be repositioned under the beam until a point of equilibrium is reached and the beam is horizontal.

What is the term used when a disk is revolving from a central point and the disk is adjusted until it reaches a point of being in balance?

Thanks

Kind Regards
Lionel

[jonesfam]

I believe the technical term is:

'Not Wobbly"

Jonesfam

[Lionelgee]

I believe the technical term is:

'Not Wobbly"

Jonesfam


Hello Jonesfarm,

Northern Queensland humour :clap2::clap2::clap2:

Kind Regards
Lionel

[Don 130]

'Balance' might just be the term

https://en.wikipedia.org/wiki/Balancing_of_rotating_masses

Dynamic Balancing International Balancing Standards Industrial (http://www.precisionbalancing.com.au/industrial-balancing-standards.html)

https://www.freestudy.co.uk/dynamics/balancing.pdf

Don.

[rangieman]

I believe the technical term is:

'Not Wobbly"

Jonesfam

Yep x2 if it wobbles go to a tyre place and let them so called pimple faced drips sort it out:angel:

[Ferret]

...What is the term used when a disk is revolving from a central point and the disk is adjusted until it reaches a point of being in balance?

a dynamic balance or a centrifugal balance - my guess.

[shanegtr]

We just refer to it as balance at work

[Lionelgee]

Hello All,

Thank you for your replies. I thought that there might be a longer physics based term for "balance".

I remember reading an article in an Australian motorbike magazine back in the 1980s. The article had an extensive written description and accompanying diagrams about what combination of forces - such as centrifugal force, plus about three other types of "forces", need to come together for a motorcycle to remain on two wheels while cornering.

There was some point where the forces came together to allow "balance" and forward momentum to continue while cornering. So two rotating disks moving forward while balanced. Go beyond that point of "balance" and things get dire very quickly.

P.S. Two Wheels Magazine ... plus Gyroscopic Force ...

Kind Regards
Lionel

[Eevo]

https://www.youtube.com/watch?v=dq6T5BojXc8

[bee utey]

Balanced, Like, It's Seriously Smoooooth = BLISS :p

[Pedro_The_Swift]

https://www.aulro.com/afvb/images/imported/2017/02/632.jpg

[V8Ian]

https://www.aulro.com/afvb/images/imported/2017/02/632.jpg
TD5? :D

[pop058]

TD5? :D

You wish :D

[ramblingboy42]

it is called dynamically balanced.

[BigBlackDog]

On helicopters our engineers do a static balance when attaching new blades, then dynamic firstly on the ground, then hover then forward flight at various speeds, so the blade is balanced both horizontally, with weights, and vertically, with aerodynamics. And yes, it does take ages to get right some days

[pop058]

On helicopters our engineers do a static balance when attaching new blades, then dynamic firstly on the ground, then hover then forward flight at various speeds, so the blade is balanced both horizontally, with weights, and vertically, with aerodynamics. And yes, it does take ages to get right some days

In your line of work, I would imagine balance would be relatively important :D

[Lionelgee]

Hello Big Black Dog and Rambling Boy

Do you mean something like this ... Accessed February 4th 2017 from

https://www.youtube.com/watch?v=8BnES4T1RDk

An oldy and a goodie with really advanced graphics ..... for its time.


Accessed February 4th 2017 from https://www.youtube.com/watch?v=Wm5OmBITBt0

Kind Regards
Lionel

[Old Farang]

On helicopters our engineers do a static balance when attaching new blades, then dynamic firstly on the ground, then hover then forward flight at various speeds, so the blade is balanced both horizontally, with weights, and vertically, with aerodynamics. And yes, it does take ages to get right some days
Depending on the type of rotor system, what is more difficult to achieve is blade tracking, even when the blades may be both statically and dynamically balanced.

And what is shown in the video with the Chinook is "ground resonance", not out of balance blades.

[ramblingboy42]

I used to use an accelerometer coupled to an interrupter on the main mast with a pair of reflectors on the rotor tips. This was connected to a strobe which flashed in sync to the reflectors. I used a pair of "3's" , one reversed and my goal was to form an 8 when the disc was flying correctly.

Biggest problem was the bloody pilots would try to fly to the rotors so I started putting the reflectors out over my shoulder(by shifting the interruptor) so he couldnt see it....that ****ed them off.

yes Old Farang you are correct.

[BigBlackDog]

Depending on the type of rotor system, what is more difficult to achieve is blade tracking, even when the blades may be both statically and dynamically balanced.

Yeah tracking is what I meant by vertical balance, just keeping it simple. :)
Or hint more frustrating to track something in the wind, think it's pretty good only to fly next day in the calm with passengers and get the life beaten out of you in the vertical. Bell and their big 2 blades...

[Blknight.aus]

the point of engineering balance is a compromise.

its some where in between the point where the accountants gasp and whine about "it cost how much and you want us to pay for that , no way go do it cheaper I dont care if its going to fail early or be a ***** to work on thats not my problem just do it cheaper" and havign the mechanics liberally throw expletives around like punctuation and heartbeats while saying things like " when I find the engineer who designed this pile of rubbish I m going to feed him testicle first into a bench grinder ITs taken me hours of work and I still cant get to the bloody thing to pull it out or off and ITs going to cost a fortune to fix what some dumb ass accountant forced into and the customers going to gripe and whine about the cost because the parts only a few dollars but its " ..........

Mechanic balance is that thing that lets me get home on a push bike after a couple of cans of mechanics lubricant after taking nearly a day to fix something that some engineer failed to balance far enough in my favor when it comes to ease of repair and access.

[superquag]

Amen :mad::p:mad:

(And don't forget the use of unusual fasteners to fit into tiny spaces and their expensive/rare special tools to undo them...)

[Slunnie]

Hello All,

What is the point of balance called when something round and dynamic - such as a car tyre, is put into a "balancing machine" and weights are added to it until it is "balanced". Or in the case of a flywheel metal is removed until the fly wheel is balanced or runs "true". Other than "balanced" or "True" what is the term used in mechanical engineering parlance?

Is it the point of equilibrium? Or is it known by another name? For instance, in the example of a balance beam with two uneven weights located at opposing ends - a pivot can be repositioned under the beam until a point of equilibrium is reached and the beam is horizontal.

What is the term used when a disk is revolving from a central point and the disk is adjusted until it reaches a point of being in balance?

Thanks

Kind Regards
Lionel
You're not thinking centre of gravity?

[Old Farang]

What sometimes leads to confusion with balance is "resonance" or the mechanical resonant frequency of a moving mass.

A small example is the balance wheel in a clock, where it is used to advantage to regulate the movement to maintain the time as we known it.

Your Land Rover has an harmonic balancer, which if not working is likely to shake a lot of money out of your pocket!

Big ship marine diesel engines ALWAYS have a certain critical RPM, which if allowed to run at critical speed will rapidly destroy the engine. I am talking about slow speed diesels of around 100 to 120 RPM.

An extreme example of resonance is shown with the video of the Chinook helicopter. The type of rotor system used is prone to "ground resonance", no matter how well balanced the rotor system may be.

[shanegtr]

What sometimes leads to confusion with balance is "resonance" or the mechanical resonant frequency of a moving mass.

A small example is the balance wheel in a clock, where it is used to advantage to regulate the movement to maintain the time as we known it.

Your Land Rover has an harmonic balancer, which if not working is likely to shake a lot of money out of your pocket!

Big ship marine diesel engines ALWAYS have a certain critical RPM, which if allowed to run at critical speed will rapidly destroy the engine. I am talking about slow speed diesels of around 100 to 120 RPM.

An extreme example of resonance is shown with the video of the Chinook helicopter. The type of rotor system used is prone to "ground resonance", no matter how well balanced the rotor system may be.
High speed turbines also have critical speeds that need to be pushed past quickly during startup. They will often have 2 or 3 critical speeds on the way up to opertating speed. A good example of a critical speed is a bench grinder when its running down - starts to reduce speed nice and smoothly, then gets a point where is shakes itself around a fair bit and then smooth off again. Thats a critical speed and occurs when the rotating speed lines up with a resonate frequency - which then amplifies the machines vibration

[JDNSW]

One of the aircraft types I used to fly (can't remember which one) had the usual band of green ending in a red line on the tacho - with an orange band about 100rpm wide a few hundred rpm below the red line, and a placard warning you not to operate in that band.

Same thing.

John

[BigBlackDog]

One of the aircraft types I used to fly (can't remember which one) had the usual band of green ending in a red line on the tacho - with an orange band about 100rpm wide a few hundred rpm below the red line, and a placard warning you not to operate in that band.

Same thing.

John

Was it an arrow?

[JDNSW]

Yes, I think that would be right - an Arrow 180.

John

[Lionelgee]

Yes, I think that would be right - an Arrow 180.

John


G'day John & BBD,

One of these ... Accessed February 7, 2016 from,
Piper PA 28R Arrow aircraft history performance and specifications (http://www.pilotfriend.com/aircraft%20performance/Piper/17.htm)

Kind Regards
Lionel

[hodgo]

Hello All,

What is the point of balance called when something round and dynamic - such as a car tyre, is put into a "balancing machine" and weights are added to it until it is "balanced". Or in the case of a flywheel metal is removed until the fly wheel is balanced or runs "true". Other than "balanced" or "True" what is the term used in mechanical engineering parlance?

Is it the point of equilibrium? Or is it known by another name? For instance, in the example of a balance beam with two uneven weights located at opposing ends - a pivot can be repositioned under the beam until a point of equilibrium is reached and the beam is horizontal.

What is the term used when a disk is revolving from a central point and the disk is adjusted until it reaches a point of being in balance?

Thanks

Kind Regards
Lionel


There is a show on paid TV called the science of stupidity If you were to watch a couple of shows I am sure you would pick it up

[BigBlackDog]

G'day John & BBD,

One of these ... Accessed February 7, 2016 from,
Piper PA 28R Arrow aircraft history performance and specifications (http://www.pilotfriend.com/aircraft%20performance/Piper/17.htm)

Kind Regards
Lionel

Yeah that's the one.
A Bell Jetranger heli has a tail rotor vibration danger area to, it occurs at start at idle and you have to accelerate the RPM through that band.

Rod