Hi all, I’m designing a three points hitch and I know there is the ASAE S that imposes some geometric constraints. I don’t understand one. Buy ASAE S Agricultural Equipment – Three-point Free-link Attachment For Hitching Implements To Agricultural Wheel Tractors from SAI Global. Buy ASAE S THREE-POINT FREE-LINK ATTACHMENT FOR HITCHING IMPLEMENTS TO AGRICULTURAL WHEEL TRACTORS from SAI.
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Register now while it’s still free! Close this window and log in. Are you an Engineering professional? By joining you are opting s17 to receive e-mail. Promoting, selling, recruiting, coursework and thesis posting is forbidden. I don’t understand one constraint called “mast adjustment height”, it isn’t drawn on the standard. Does anyone know, what it is? I saw that there is a reference to ISO Appears that they are identical – so that doesn’t help.
Note that the “Mast adjustment height, lowest position” is the same as the “lower hitch point. The geometry is designed to kick the rear of the implement up at the high lift range to facilitate transport asaf long implements i.
Dear IceStationZebra, thanks a lot, with your explanation I have understood it perfectly. What a pity ISO didn’t provide any picture for it. Do companies have to design a three point hitch in according to this standard or not?
I haven’t found any refereces so far.
Their use by anyone engaged in industry or trade is entirely voluntary. Conformity does not ensure compliance with applicable ordinances, laws and regulations.
Prospective users are s2217 for protecting themselves against liability for infringement of patents. Realize that all of these organizations use people in the respective industries to come up with the standards that they will use.
What this basically means is that there is very little outside oversight, unless it concerns the public good. This is where homologation comes in. What you need to do is find out if the country where you want to sell your equipment makes them mandatory. Individual governments can make them mandatory, or go above and beyond!
The EU is a prime example. There are the “directives” that cover any machine sold in the EU. A few of the main ones are: Italy is a good example of this. And then there are countries like the USA where standards may not be required by law, but if someone gets injured and you don’t follow the “voluntary” safety standards you will loose a lot of money in court cases.
Hi IceStationZebra, thanks for your reply. In the directive you have mentioned, any ISO standard isn’t mentioned about the three point hitch, but few companies in their 2s17 datasheet write the three point hitch category, so it should mean the most of them don’t follow any standard, right?
It would help a lot if you told me which country saae countries you are interested in. They probably don’t mention it because it has been the standard so long that it is assumed, but as far as I know all the large tractor manufacturers in Europe, Australia and Americas follow the 3pt standard. In reality it is probably tough to meet all the 3pt requirements considering all the other options and tire choices that are offered in the various markets.
I wouldn’t be surprised if they cut corners a little, but you would s2177 to measure very carefully to find out. But isn’t a tractor sold with only one front and rear radius index? By the way for the dynamic radius index I mean the radius that it is used exclusively for the calculation of forward ground speed during homologation procedures.
OK, you are talking about the tire rolling radius.
ASABE Adopts ISO Standard for rear-mounted 3-point linkage.
I have never been involved with the homologation of a tractor, but my assumption is that you would have to take whatever the worst case is for the size of tires offered. Some aspects of homologation will be worse off with tall tires, others with short ones.
This is what I had to do for a articulated loaders. You also have to consider other options. Will you see different performance with a “quick hitch”?
What about two wheel drive vs. Some tractors have multiple holes for the top link, meant to increase the tipping action with long implements like plows. Many tractor chassis also come with different classes of 3 pt. For example, it is very common in North America to find tractors with class 3 and 4 narrow. Hi IceStationZebra, thanks for your reply, does the rolling radius change on the several configuration for a specific tractor?
There of course will be minute changes due to gross vehicle weight differences, but they will be minor. Different tire configurations will alter the pitch of the tractor. Some tractors have both and rpm PTO shafts, at slightly different heights.
Three-Point Free-Link Attachment for Hitching Implements to Agricultural Wheel Tractors
As far as tipping action goes, I am specifically talking about how the geometry tips the implement forward as it is raised.
If you have a long implement like a 6 bottom plow you may want to increase the tipping action to increase road clearance for the last bottom during transport. Thanks IceStationZebra, I got it.
It appears mainly so they could introduce the idea of adjustable lift rods. I wouldn’t be surprised if there were a few tractors without, but the vast majority have had at least one adjustable rod.
But what I was really getting at is that to define adjustable lift rods you first have to define what a lift rod is. Hi IceStationZebra, I was again on holiday. Btw the lift rod regulation was introduced in order to enchance the three point hitch connectivity, right?
I think the main reason for adjustable lift rods is so you have some adjustment when plowing with one wheel in the furrow.
I have never used it for any other reason. I guess you would probably use it on any implement that is nonsymetrical. Thanks for your reply. Regarding to the three point hitch design, I have found this paper, https: In the three point hitch design I think it is also necessary to take into account the lifting perfomance measured in according of the OECD code.
There I created a tool to design a TPH. Would it be useful for designers to take into account to design a three point hitch? I have another doubt regarding the three point hitch. I’m looking to nebraska test report of some tractors and I noticed the three point hitch can lift a load higher than the tractor stability limit.
This sounds weird to me, since it’s not a safe working condition. Why are three point hitch designed to develop so high lifting loads? I have seen the test done with a bare tractor frame with no engine or tires bolted to the floor. There are no stability limits in the testing so the tractor manufactures keep pushing the limit so they can claim to have the strongest tractor. Which, like you pointed out can get silly. In reality you don’t want a lack of lifting force to be lowest limit in your system.
ASABE Adopts ISO Standard for rear-mounted 3-point linkage.
This will make customers think you have a weak tractor. Farmers will add weight to the front of the tractor to offset the lack of stability. On the negative side this is stressful to the tractor structure, adds to soil compaction, and burns extra fuel.
I noticed all companies are set up to a similar lifting force for the same tractor type. I was wondering why just that lifting force was choiced by producers. I think somehow it’s the force necessary to lift the implement at a specific vertical acceleration. Do you think it’s a good argument? They are usually fairly abrupt. I’m not suprised that similar tractors from different manufacturers have similar lifting forces.
As customers compare specifications nobody wants to appear lacking. I got the point. So when designers design a asar point hitch, what do they take into account?
I found an old paper, where it’s written it is necessary do apply two times the gravity force of an implement to remove it out from the ground. Taking into account the heaviest implementI get the same order of size of the maximum lifting force for a specific tractor size.
Therefore in normal working condition the lifting force is lower than the one measured with the OECD test. What do you think about it? One has to realize that these standards are created by representatives from the companies who are selling these products, not independant engineers or scientists.
And as such they all have an interest in making their products look good. They could have chosen a distance that was farther back, but then the number would be smaller and infer less strength. Sometimes the standards come from a group that already has a standardized process, maybe has done some comparative testing, and the others just agree to adopt it.