Weight calculations........

[hillbill]

The fact that i didnt listen at school 20some years ago has eventually caught up with me. So, essentially i need to find the formula to calculate the load gain on the tractor 3 pount linkage, by adding a extra furrow on the plough. If the extra furrow and disc weigh, hypothetically, 250kg, what extra load in kg would there be on the tractor end?
Cheers in advance.....

 

[Farmer_Joe]

It will depend on length of plough, the longer it is the higher the loading will be as it get exponentially more the further away it is.

same principle as booming a fixed weight out on a loadall the fourth out it goes the more weight force on the machine

 

[hillbill]

It will depend on length of plough, the longer it is the higher the loading will be as it get exponentially more the further away it is.

same principle as booming a fixed weight out on a loadall the fourth out it goes the more weight force on the machine

Yeah i understand that, but there'll be a calculation to take into consideration, length from the point of lift and weigh of the item fastened to the lever as it were....

 

[Drillman]

Hang 3 or 4 tractor weights on back of existing plow if tractor picks it up without issue order the extra furrow.

 

[Sharny dubs]

Force × distance from pivot. And remember the pivot will be the lower link pins on the tractor, not the headstock of the plough.

 

[Exfarmer]

If you are looking to calculate the difference in the force, you will need to know the pivot point of the plough( roughly the mid point of the plough) . The distance of this from the top link of the tractor X the weight.
then you need to do the same for the plough in the new configuration.
but in general terms if you take the weight ofnthe new furrow attachment , times The length from the top link plus half the extra added you will have the extra force, but you will actually overestimate as the front of the plough is heavier than the back end

 

[mo!]

Surely this is only useful if you know what the current load is? I think I'd be ringing the manufacturer's technical rep rather than trying to calculate.

 

[Boohoo]

Don't most plough manufacturers list the lift requirements for their various models?

 

[Zebbedee]

The fact that i didnt listen at school 20some years ago has eventually caught up with me. So, essentially i need to find the formula to calculate the load gain on the tractor 3 pount linkage, by adding a extra furrow on the plough. If the extra furrow and disc weigh, hypothetically, 250kg, what extra load in kg would there be on the tractor end?
Cheers in advance.....

Be easier telling us what tractor and what Plough you are talking about? The calculations you are talking about were never taught in school or certainly not mine,,,,,,

 

[Mur Huwcun]

Be easier telling us what tractor and what Plough you are talking about? The calculations you are talking about were never taught in school or certainly not mine,,,,,,

Not once did any maths teacher tell us that angles and pythogaras and algebra and Sin Cos and tan could be used for usefull calculations such as roof pitch and designing machinery or half of us would of actually listened!!!

 

[JWL]

My boy was well impressed with me when he was doing his maths at GCSE and some of his A level maths as I could keep up and match his knowledge and explain some of the formulas into real world situations. I've allways found it amazing how much I use the likes of Pythagoras especially the 3,4,5 triangle rule

 

[bitwrx]

You can work this out exactly with two trips to a weighbridge to take some axle weights (one with current plough, one without), and by knowing the weight of the additional furrow.

If it was me, id be seeing how much weight I could remove from the front of the tractor with the current setup before it feels iffy, then asking myself if I'd be happy to add at least that much weight on top of what was already there. If so, then go for it.

 

[Exfarmer]

My boy was well impressed with me when he was doing his maths at GCSE and some of his A level maths as I could keep up and match his knowledge and explain some of the formulas into real world situations. I've allways found it amazing how much I use the likes of Pythagoras especially the 3,4,5 triangle rule

I get very angry when I hear some prat saying how little use maths is apart from basic Arithmetic. I have used maths all my life when farming and this applies to a huge number of professions.
I cannot remember any situation when Shakespeare has had any use at all, yet kids spend years studying this Tudor playwright, just to make a quote in an end of year exam.

 

[Exfarmer]

You can work this out exactly with two trips to a weighbridge to take some axle weights (one with current plough, one without), and by knowing the weight of the additional furrow.

If it was me, id be seeing how much weight I could remove from the front of the tractor with the current setup before it feels iffy, then asking myself if I'd be happy to add at least that much weight on top of what was already there. If so, then go for it.

Sadly not correct, as the extra weight is at the far end of the plough so exerts a far greater force than simply bolting on another 200 kg. It also puts weight on the back axle by removing weight from the front.

 

[hutchy143211]

One thing that's worth knowing is a bit of structural engineering/mechanics and how to resolve forces and moments (granted I studied structural engineering) you can work out the forces at any point in a system. I've used it to design irregular gates and all sorts. The way to do it is look at the whole system and make virtual cuts wherever you need i.e. in this case the link arms. If you like I can find some examples/help if you want.

 

[Scrambler]

Do you want to know the extra force pulling on the top link (extra mass x distance from top link divided by the vertical distance from the lower lift arms to the top link mounting point on the plough) or the extra force needed at the end of the lift arms to lift the plough (difficult to calculate due to the fact the geometry of the 3 point linkage will have a large affect on this), or how much lighter the front axel will be (extra mass x distance from tractor rear axel divided by the tractor wheelbase).

I think.

 

[bitwrx]

Sadly not correct, as the extra weight is at the far end of the plough so exerts a far greater force than simply bolting on another 200 kg. It also puts weight on the back axle by removing weight from the front.

Snis correct.
It's a simple sum of moments around the back axle of the tractor.

Without knowing the current axle weights (no plough), you can't calculate the distance from the centre of mass of the tractor to the back axle, or the overall mass of the tractor.

Without knowing the current axle weights (with plough), you can't calculate the moment the current plough exerts.

As you correctly say, you need to know how far the new furrow is from the back axle, otherwise you can't calculate the new moment balance (i.e. the new axle weights on the tractor, otherwise known as whether you'll be pulling a wheelie at each headland!).

ETA: I've re-read the OP, and I think I'm answering the wrong question. I'm answering "will it wheelie?"; I think the OP was asking "will it lift it?". In which case I'd use a "work done" approach (force x distance), comparing the specified capacity at the ball ends with the new mass of the plough. But only if I was hell-bent on doing a calculation. In reality, I'd just do what @Andrew suggests below.

 

[bitwrx]

One thing that's worth knowing is a bit of structural engineering/mechanics and how to resolve forces and moments (granted I studied structural engineering) you can work out the forces at any point in a system. I've used it to design irregular gates and all sorts. The way to do it is look at the whole system and make virtual cuts wherever you need i.e. in this case the link arms. If you like I can find some examples/help if you want.

Indeed.
In fairness to everyone who is saying they wish they'd paid more attention at school, I don't remember being able to do this competently until my first year at university (mechanical engineering), although I suspect it was on the syllabus at A-level at least.

It's not tricky when you get your head round it, but getting your head round it can be tricky!

 

[Andrew]

There is a simple formula to calculate it, but getting the right information to put into the formula will be tricky.
Unless you are familiar with the equations then it’s too easy to make a mistake and then your result is worthless.

I would suggest hanging a weight, equivalent to the extra furrow, to the end of the plough and see if it’ll lift it.

 

[hutchy143211]

Indeed.
In fairness to everyone who is saying they wish they'd paid more attention at school, I don't remember being able to do this competently until my first year at university (mechanical engineering), although I suspect it was on the syllabus at A-level at least.

It's not tricky when you get your head round it, but getting your head round it can be tricky!

Very true, the maths part is the easy bit once you've figured out whats going on. The hard bit is simplifying the system to work it out and then working out which direction everything is going to get equilibrium. I remember it from A level but they never taught you to understand what was going on, just to punch it in a calculator and get an answer. Engineering makes you think whats going on and once you understand that like you say you can solve most things!