How much power, force ......

[loves80z]

BHD
The estimate of the pdf I found was 87% of pto hp for drawbar hp. That matches well enough with the numbers u posted.....on concrete. On firm soil it is 72% or 44hp.

 

[loves80z]

To generalize i size a shear pin for a little over BHD's drawbar force or 87% pto hp, size the width of implement based on the 72% of pto hp for firm soil i think i should be good. Anyone thoughts?

 

[RedNeckRacin]

Why not do some research on the dimensions of manufactured implements Instead of reinventing the wheel. I dunno what you other engineers LearNed I school but I learned to K.I.S.S. problems.

 

[SPYDERLK]

The max steady force you can apply is very near the weight the tires carry, if AGs. Getting brought up short will spike it higher.

 

[loves80z]

Thank you for the reverse engineer question. My thoughts: What size implement for my tractor? Do i need the heavy duty or the standard? My soil. What i have seen when i look at this is people listing what worked for them in their situation. I hope to define my situation then use that for a basis for all sizing. Sizing purchased, built, custom and revers engineering. I am much more cumfortable pointing to a chart and using it and some basic facts to make my selection as opposed to taking a pole and trying to figure out if i fit a situation and rely on an individuals opinion of what worked well for him. That being said the reason i am posting is that i value the opinion of the members here. I know that the situation is organ8c and cannot be completely defined with calculations without a lifelong effort and i want some impliments by spring. I need a baseline to start with. The pdf makes sense to me and will allow me to do some custome implements without the luxury of reverse engineering. That and the experience of people here to help me make sure i have not missed some factor i did not anticipate in my inexperience.

 

[jb92563]

I agree with KISS and also like that Nomogram in the PDF so perhaps the simple answer lays there.

Once worst case I can think of is when the box blade gets hung up on a root, rock etc you have the pull of the tractor to consider and you will want to know the fully ballasted weight, not just the factory spec, and of course your speed when the blade gets hung up.

We want to consider the strength of the drawbar or 3 pt elements so as not to break or bend the arms off. A shear pin is a good idea to protect your tractors parts.

 

[RedNeckRacin]

While I like to geek out on calculations I think you are over thinking things. Many manufacturer's will rate their implements based on pto hp or weight of the machine. AS long as your generally within their specs you will be more than fine. There is a general rule of thumb for rotary mowers and plows. I cannot possibly think of anything that you are going to gain by going through this exercise. Designing something for a tractor to be the most "efficient" is not needed. There are entirely to many variables to take into consideration. That's precisely where the "rule of thumb" rules came from. There is also a bias between the older iron from the 70'sa nd 80's vs the lightweight stuff from the current suppliers.


The other thing is, if your trying to save pennies, look around for used implements. Your likely going to find a great deal on something that is slightly larger or smaller than your tractor would be optimized with. This is not a problem. Rather a challenge to learn to operate your tractor within those limitations. After all, we all enjoy tractor seat time!

 

[BHD]

the Nebraska tractor tests have been considered the Bible on tractor horse power, as they have done independent tests for nearly as long tractors have been made,

most implements will have a recomedated tractor HP, for example I have a 10 foot mower and a 90 hp rated tractor, 96% of the time I have horse power to spare, but there are times when I am in weeds and grass that is as tall as the rear tires, you have to gear down,

same as with a chisel, normally I pull a 16 foot JD 100 chisel in the field, but I made a 7 foot unit for breaking up ground so I can break up soil to make the speed mover, (a towed box blade) work better in dry and unbroken ground, in un worked ground the 7 foot unit can make the tractor grunt,

much is how you going to use the implement, for example the speed mover, mine is a 8 foot unit, if one is just working the drive way, a 30 hp tractor could do it, but there have been times I have spreading truck loads of soil or a old farmstead that was dug up and removed from existence, and all the foundations and building removed the concrete buried about 10 feet below the surface, was at times all most more than my tractor could handle, (back it up on a mound that was as tall as the tractor cab and pull off a full box load of soil and spread until flat as a pool table,)

 

[BHD]

one more thing if your pulling hard you want some tire slip, up to 10%,

type of tires can make a big difference, a radial tire vs a bias ply tire, the Ag rear: 13.6-38 that were factory should be a good choice, yes a wider or a radial tire will provide more traction, but it would be better for the tractor to have some slip.

 

[loves80z]

One thing that has been very confusing to me is the hp ratings from manufacturers. A rotary implement using pto and shear pin is easy. Now i look at a box blade and its far from clear. A 55 hp land pride says i can use a 5 ft to 8 ft. I've read lots of threads about sizing and still walk away scratching my head. If i can use the charts like in the pdf i posted, the answer is clear. It factors in many variables and quantifies them pretty well. It tells me what information is needed and gives me a procedure.

I have never been accused of overthinking before.......well at least not in a few weeks.