You need balast or you will trash your front axle!!!! really?

[s219]

Doesn't the horizontal distance forward of the front axle change as the height increases?

Of course, but that's geometry, not physics. When you derive the physics equations, it comes down only to horizontal distance. Measure it with a ruler wherever the bucket sits.

 

[ovrszd]

Of course, but that's geometry, not physics. When you derive the physics equations, it comes down only to horizontal distance. Measure it with a ruler wherever the bucket sits.

Bear with my ignorance.

Then the physics equation changes as the height increases because the horizontal distance is changed?

If so, then the vertical height does in fact change everything??

 

[CobyRupert]

Bear with my ignorance.

Then the physics equation changes as the height increases because the horizontal distance is changed?

If so, then the vertical height does in fact change everything??

Yes. It also adds lateral leverage if you're not on completely flat ground to tip you over sideways.
Hey, speaking of tipping over sideways have we started arguing about the role of the front axle pivoting yet?!

 

[RaydaKub]

Doesn't the horizontal distance forward of the front axle change as the height increases?

Yes it does, but to calculate the forces and leverage at a given static point, the vertical is not a factor. But how often are we in a static situation?

 

[AxleHub]

Glade, it would seem 2 other numbers effect the weight shift change percentage and efficiency to your calculation:

1. How far forward of the front axle is the load.

2. How high is the load (thus effecting cog)

The reason I presented these two points is the following:

1. Glade uses distance assumptions for distance of weight behind the rear axle. But the efficiency of the calculation also relates to the weight transfer from the front axle it would seem. Front weight close to the front axle would be much more efficient than if its 2 or 3 feet forward of that front axle it would seem. Using only wheelbase assumes the weight is directly over the front axle it would seem instead of leveraged weight.

2. Point two about how high the front weight is located is an issue of two things . . . a change in center of gravity for side to side effect as well as a repositioning of cog front to back. High weight has an impact on the "weight shift" back to the rear because it is closer to weight being directly over the front axle AND high at the same time. We all know high weight makes a tractor less stable and more prone to tip or weight shift either side to side or front to back. That also effects calculations for efficiency of weight transfer it would seem.

Yet Glade hasn't considered either of these points in his calculations. Wheelbase is only part of the formula needed because leverage positioning and gravity's pull (or the "ease to create shift") are involved it would seem.

But lets hear from the physics folks on their viewpoint . . as I contend that geometry and physics are linked or relational when physics is discussed.

 

[ovrszd]

Yes. It also adds lateral leverage if you're not on completely flat ground to tip you over sideways.
Hey, speaking of tipping over sideways have we started arguing about the role of the front axle pivoting yet?!

Well, it appears this thread has the maturity to add the side topic of axle oscillation. Folks tend to have some very strong beliefs about that.

I'll ask the inevitable question to get this started. Is a wide front axle tractor more stable than a narrow (tricycle) front axle tractor? If your answer is yes, please explain why??

 

[ovrszd]

The reason I presented these two points is the following:

1. Glade uses distance assumptions for distance of weight behind the rear axle. But the efficiency of the calculation also relates to the weight transfer from the front axle it would seem. Front weight close to the front axle would be much more efficient than if its 2 or 3 feet forward of that front axle it would seem. Using only wheelbase asdumes the weight is directly over the front axle it would seem instead of leveraged weight.

2. Point two about how higj the front weight is located is an isdue of two things . . . a change in center of gravity for side to side effect as well as a repositioning of cog front to back. High weight has an impact on the "weight shift" back to the rear because it is closer to weight being directly over the front axle AND high at the same time. We all know high wright makes a tractor lessvstable and more prone to tip or weught shift either side to side or front to back. That also effects calculations for efficiency of weight transfer it would seem.

Yet Glade hasn't considered either of these points in his calculations. Wheelbase is only part of the formula needed because leverage positioning and gravity's pull (or the "ease to create shift") are involved it would seem.

But lets hear from the physics folks on their viewpoint . . as I contend that geometry and physics are linked or relational when physics is discussed.

Not to side track your statements here because I want to hear the technical responses. When I've got a heavy load on the FEL and I raise it to a very high level I can feel in the seat of my pants the weight transferring from the front axle to the rear axle.

 

[RaydaKub]

Bear with my ignorance.

Then the physics equation changes as the height increases because the horizontal distance is changed?

If so, then the vertical height does in fact change everything??

Exactly! The calculation is all about weight and leverage, doesn't matter if it is a tractor or seesaw. The fact that the vertical changes the horizontal on your tractor is merely an implementation detail.

 

[jenkinsph]

Yes. It also adds lateral leverage if you're not on completely flat ground to tip you over sideways.
Hey, speaking of tipping over sideways have we started arguing about the role of the front axle pivoting yet?!

Some of these guys are having enough trouble understanding the static loading. Dynamic loads are a whole new ball game.

 

[ovrszd]

Some of these guys are having enough trouble understanding the static loading. Dynamic loads are a whole new ball game.

HEY, I resemble that remark!!!!

 

[jenkinsph]

Exactly! The calculation is all about weight and leverage, doesn't matter if it is a tractor or seesaw. The fact that the vertical changes the horizontal on your tractor is merely an implementation detail.

Yes, a fork lift with the mast set plumb would not change the loading as it is raised. A fel raises its load in an arc and moves the load rearward as it rises. It still needs to be calculated at the lowest starting point to make sense as you need to make the numbers work from start to finish.

 

[ovrszd]

Yes, a fork lift with the mast set plumb would not change the loading as it is raised. A fel raises its load in an arc and moves the load rearward as it rises. It still needs to be calculated at the lowest starting point to make sense as you need to make the numbers work from start to finish.

I agree with this theory. Not to doubt, just filling in the blanks in my empty theoretical mind. Isn't the farthest point of the arc from the front axle a few feet off the ground? Doesn't the bucket get closer to the tractor when it's sitting on the ground than up a little??

 

[sd455dan]

Some of these guys are having enough trouble understanding the static loading. Dynamic loads are a whole new ball game.

If that doesn't cloud things enough, lets also Add in efficiency in static loads?????

I always thought (efficiency) was used in dynamic calculations of work/time
not static load equations??:confused3:

 

[jenkinsph]

I agree with this theory. Not to doubt, just filling in the blanks in my empty theoretical mind. Isn't the farthest point of the arc from the front axle a few feet off the ground? Doesn't the bucket get closer to the tractor when it's sitting on the ground than up a little??

Yes if the bucket is below horizontal mounting of the pins on the loader arm. So you are correct. Raising the load you would have to meet this requirement as you raise the fel through this arc.

 

[jenkinsph]

I am sure that some would think that having the fel bucket close to the axle would be best. Anyone who has to load a dump truck knows how important dump clearance is too. You need clearance between the front end to prevent bumping into the side of the truck.

 

[Snowback]

Yes. It also adds lateral leverage if you're not on completely flat ground to tip you over sideways.
Hey, speaking of tipping over sideways have we started arguing about the role of the front axle pivoting yet?!

Great example of front pivot doing its thing when not enough counter weight is used. It's a fun short video to watch at this link: https://www.youtube.com/watch?v=mRus_-ipbUo

 

[CobyRupert]

Yes, a fork lift with the mast set plumb would not change the loading as it is raised.

Interesting.
...but as soon as you move the forklift backwards, doesn't Newton's First law say you're much more likely to tip the fork truck off it's rear wheels (that is: the horizontal force required to move the raised load backwards has a torque effect about the front axle that is multiplied by this raised height?)

 

[s219]

I know that a lot of you want to link the vertical position of the front bucket load into this, but all that does is add another layer that obscures the pure physics. Generally, when deriving the equations you want to keep driving things simpler and simpler, not get more complex.

An equation I posted back in #39, was:

F * LF = R * LR

This equation has to hold in order for no additional load to be applied to the front axle. In other words, you can think of this as a way to calculate the required rear counterweight so that no added load is placed on the front axle.

Here:

F is the load on the front loader
LF is the horizontal distance from the front loader's load to the rear axle
R is the load on the three point
LR is the horizontal distance from the three point's load to the rear axle

That tells us that the rear counterbalance load must be:

R = (F * LF)/LR

So that gets it down to forces and horizontal distances, and you cannot get it simpler than that.

Now, of course LF is geometrically related to the angle of the loader, so I could rewrite it as:

LF = LA + R * cos(theta)

Where: LA is the horizontal length from the rear axle to the front loader arm pivot, R is the "radius" that the front load arcs through, and theta is the angle from horizontal. With that, the equation would become:

R = (F * (LA + R * cos(theta)))/LR

If you instead want this in terms of the height of the bucket load H, it becomes:

R = (F * (LA +H /tan(theta)))/LR

All of these equations give the same result, just using different variables. But we had to pull geometry and complexity into this to express it in terms of something other than the horizontal lever arm. Complexity is the enemy of fundamental understanding. If you require complexity to understand the physics, you blew it!

Also note in this case we can use a single variable of horizontal distance, LF. But if we want to rework the equation to get away from that most fundamental form, we now back up to something that requires three variables, LA, vertical distance (H), and angle from horizontal (theta). We'll never be able to make this depend purely on the vertical distance, because it's not in the physics. If you want this to depend purely on a single length variable, that will have to be horizontal distance LF.

 

[s219]

I should add, in cases when using statics equations and summing moments, you should always look at the problem so that you are visualizing the lever arms perpendicular to the forces. Always. So in the case where all our loads come from gravity aiming straight down vertically, the lever arms are all going to be horizontal.

A good physicist can look at this problem and in their mind see those horizontal lever arms superimposed over the more complicated tractor. It's almost something that flashes in front of your eyes. What you are doing is immediately and viscerally simplifying the problem in front of you.

I think farmers, lumberjacks, riggers, and other practical folks who incorporate physics into their work (whether they know it or not) are doing the same thing without the equations or the physics. They can look at a practical problem and know the physics.

 

[CalG]

I should add, in cases when using statics equations and summing moments, you should always look at the problem so that you are visualizing the lever arms perpendicular to the forces. Always. So in the case where all our loads come from gravity aiming straight down vertically, the lever arms are all going to be horizontal.

A good physicist can look at this problem and in their mind see those horizontal lever arms superimposed over the more complicated tractor. It's almost something that flashes in front of your eyes. What you are doing is immediately and viscerally simplifying the problem in front of you.

I think farmers, lumberjacks, riggers, and other practical folks who incorporate physics into their work (whether they know it or not) are doing the same thing without the equations or the physics. They can look at a practical problem and know the physics.

Well put s219!

All forces (loads if you will) can be resolved into equivalent horizontal and vertical components. A start towards understanding a system through Vector Analysis.
Cranes and gin poles lift sizable weights without a lot of counterbalance by directing the lions share of the "tipping moment" into a vertical component.

The arc of a loader arm moving the CoG of the filled bucket is an unnecessary complication. The masted fork lift is a perfect example of why height should not enter into the original topic discussion. It may lead to other aspects however. The inertia aspect of moving off with a high load is an ENTIRELY different discussion. Considering the way this thread has gone, I suggest NOT going into that. ;-)