Go Bottom3 point hitch position
 | gerard
Join Date: Mar 2004 Posts: 36 kentucky 
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2000-03-16 13808
I noticed the top link of my 3 point hitch has three positions, vertically aligned. Can anyone explain the pros/cons/reasons I would use the bottom position vs the top etc?? I know it will change the angle of the top link slightly I just don't see how this would help/hinder implement use other than allowing the top link to be slightly longer/shorter at full extension. Murf, Bird Senter, you out there??
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 | Murf
Join Date: Dec 1999 Posts: 7249 Toronto Area, Ontario, Canada 
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2000-03-16 13811
Gerard, without making a physics lecture out of this... The vertical position differences change the geomotry of the hitch. This changes the way the load is transfered to the tractor, which changes the traction, etc., of the tractor. If you look in your owner's manual there should be a listing of different implements and in which (top, bottom or middle) they should be attached to. In real world terms it really doesn't make a whole lot of 'seat of the pants' difference... However, as you pointed out, it is easier than wrestling with the lock-nut on the top link... ....
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| Joe Padavano
Join Date: Posts: 1
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2000-03-16 13814
It also changes the amount of lift at the implement. When viewed in profile, the linkages of a 3 PTH form what is known in the mechanical engineering world as a four bar link. Changing the location of the pivot points as well as changing the length of the links will change the motion of the linkage. For example, on my JD850 (which has four possible top link holes), without changing the length of the top link, the bottom hole provides significantly more lift at the implement than the top hole - but at the expense of tilting the back of the implement towards the tractor. As a rule of thumb, the upper holes will keep the implement more parallel as it lifts, but with less total lift. The lower holes will provide more lift, but with tilt. That latter situation was perfect for my 3 PTH mounted cement mixer, for example ....
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| gerard
Join Date: Mar 2004 Posts: 36 kentucky
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2000-03-16 13817
thanx for the quick response and info. Helps my understanding a little and why I haven't needed to change connection points yet as all I have is a box blade and york rake. Both lift with no problem and adjusting the length of my top link works for the angle on both. ....
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| Bird Senter
Join Date: Jun 1999 Posts: 962 
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2000-03-18 13875
My B7100 also had 3 mounting positions for the top link and I experimented with them a little at first, then quit ever changing it. Now my B2710 only has two positions and the manual says the top one "is standard" and the bottom one "is only used when there is some obstacle that prevents you from using the standard." I haven't ever used the bottom one. And of course I agree with the other reponses; if I ever need to tilt an implement forward more than I can by shortening the top link, then I'll use the other position. ....
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| Murf
Join Date: Dec 1999 Posts: 7249 Toronto Area, Ontario, Canada
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2000-03-18 13889
The main reason for the different positions for the top link is not something that matters to most owners. It is a feature which is really only applicable to primarily field (plowing, discing, harrowing, etc.) work where maximum traction with minimum weight. In Japan (and most other parts of Asia) a "Compact" is a full-sized tractor. The average farm is something like 3-5 acres, which was about the maximum amount of land which traditionaly could be worked by a single family. It's only here in North America that these machines are viewed as anything less than a "farm" tractor.... ....
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| Roger L.
Join Date: Jun 1999 Posts: 0
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2000-03-18 13897
Another reason for these different top link positions is if the tractor has draft control. A selection of top link holes are always found on tractors with 3pt draft control. The different leverages represented by the different holes allow the implement to apply a different load to the top link mounting. Selecting a mounting hole gives the operator control over how much of a load he wants to pull with the ground-engaging implement before the automatic draft valve is opened. ....
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