When to use long or short pins in 3pt arms?

[wwwfarmer]

I am making a bed lifter implement and would like to talk about pin length for lower (or upper) arms of 3pt attachment. Take a look at these to examples. The important dimension is B. It is 5in(~130mm) in second image and 3 3/4in(~95mm) in the third. Since this is for category 2 tractor, I usually just use width of ball in the arms (45mm/ 1 3/4inch), ad the width of the metal on the left and right(2x1/2 inch), ad 1/2in of clearance and pick the shortest pin that is appropriate. But there are many pin length options and it got me thinking that in some cases it is preferred to have 2 inch(50mm) of clearance or just 1/2in as is often with stepper pins.

What are your thoughts on this? What pin length (and clearance) do you normally choose and why?

 

[oosik]

I will pass on what I know. Your top picture shows the attachment point for Class 1 and Class 2. Class 2 being the outer attachment point. The pictured attachment points and pin look like what is on many of my implements.

Several of my implements have this attachment configuration. The pins that come with these implements are as shown in your top picture. The fatter section for Class 2 - the thinner section - Class 1. As you call it - a stepper pin.

I guess I'm not quite sure what you are asking. I always use the stepper pins whether the originals or new ones I purchase at the Kubota dealership.

Why would you want to go with a shortened pin? I always attach my implements at the wider - Class 2 - connection point.

FWIW - I don't think ball ends of my 3-point arms would fit in the Class 1 fixture. Ball ends with reducer bushings being too wide. It might if I chose to grind down the bushing and make them narrower.

But WHY???

 

[wwwfarmer]

Hi oosik, thanks for stopping by. I think I made a simple topic complicated I'll use category 2 pins only. Take a look at picture below. The red represents the link arm ball and the green represents steel from implement attachment hooks.

There is a large difference in length of the pin and space on the left and right of the arm ball. The top one has, let's say 1/2 inch on each side, and the bottom has 2. I am interested if there is any logic on why one would go with long pin with lots of room on left to right as opposed to smaller one with just 1/2 inch of spacing on each side. The only thing that I can think of is that it would be easier to attach the implement if the there is more room to operate although it is pretty easy to attach an implement with 1/8 inch of spacing on left to right.

 

[workinonit]

The primary reason I build implements with wider spacing is because I am building them to fit my quick hitch. I think I have to have about 2.5". If not for that I would build them as small as I could to eliminate side to side slop.

 

[oosik]

AH - HA. Illumination has arrived. I don't know what a bed lifter is. Is it heavy - awkward.

Anyhow - just be certain whatever width you choose for the attachment tabs - it's wide enough so the 3-point arms don't make contact with the tabs. If there is adequate clearances - I'd go with the upper diagram. I can't see that either width will be that much easier or difficult when it come to attachment.

When I attach, lets say, my HD Rhino rear blade. I always go with the Class 2 attachment point. I use stepper pins. That's what came with the rear blade.

After a short period of use - the 3-point ball ends have always worked their way out to the widest point on the pins. In other words - they are tight up against the outer "tab" of the Class 2 attachment point.

I do not look to the Class 2 attachment points to limit side to side slop. That is handled by the 3-point telescopic stabilizers.

 

[Rustyiron]

^^^ cat 2 lower pins are 1", obviously the shorter "span" is less of a bending load on them. For a bed lifter I think you're worrying needlessly.
The length of available cat 2 pins is irrelevant as long as it's long enough. (It seems like you're building around a pin length) too long is fine.

 

[WranglerX]

I have always been of the opinion if the pin works its good enough....

 

[JohnnyMX]

I measure out the width of all of my implements that hook up to my tractor and quick hitch with no issues and look at the min/max width. I want no rubbing when I pick something up and enough wiggle room that I don't need to be dead-nuts on when hooking up. Generally, with the quick hitch, if the top hook connects the rears better be good too. If you are using normal pins, you are only going to have so many options.

 

[dougtrr2]

Will the shifting side to side of the implement have any adverse effects?

Doug in SW IA

 

[LD1]

The longer spacing for the pin is to account for quick hitches. Slight variations is manufacturing....plus ease of hooking up.

When you are hooking ip an implement the conventional way...they dont need to be much wider than the tractors ball ends....because they move independently of each other. With a quick hitch trying to hook from the seat of the tractor...only leaving 1/4" of clearance makes it more challenging to hook up. You have to back up perfectly straight with little to no room for error.

So it depends on how you plan on attaching is what rout I would take.

The first pic shows a stepped pin. You CANNOT use just a single 1" pin to fit and forget about the cat I side. Because ONLY the outer hole is 1". The middle is 7/8". The pin is stepped down. That way it only needs a lynch pin on one side