Now what did I do?

[Alpha Dog]

OK, after mocking up a "simulated hydraulic cylinder" using PVC pipe and fittings, I've taken another full set of measurements. It looks like my last dilemma on this particular issue is "too long, or too short?"
My measurements suggest that to completely open the grapple, I need to have a cylinder that retracts to 16 1/2" and to fully extend the grapple (to the point where the cyinder has 1/4" to 1/2" clearance before it would contact the grapple) would be 24 1/2". The choices for cylinders I've found are either 15 1/2" retracted x 25 1/2" extended, or 13 1/2" retracted x 21 1/2" extended. The shorter one means that I have to add some more metal on the "spurs" I'm going to put on the grapple, (using some 1/4" plate and some 1/4" thick 2"x2" angle iron), but it's only about 2 extra inches of steel.
So, here's where my ignorance of hydraulics comes in, do I go for the longer cylinder and just make sure it has "positive stops" to keep it from getting lateral loads again, or do I go with a shorter cylinder that will neither fully open, or fully close the grapple. (Or is there another option, finding a "Goldilocks - just right" cylinder somewhere?)

All input appreciated.

 

[J_J]

Is there anything small enough that you have to pinch the object between the bucket and the grapple?

If you are limited to a particular cyl, and it is short, you could realign the cyl end tabs for a perfect fit.

You could also cut and weld a new end piece on the cyl rod.

Extend the teeth on the grapple.

 

[woodlandfarms]

You can have a custom cylinder made. $$$. I would say go for short. My logic is this. you are not going to ever clamp fully down, you will always have something in the bucket. And as it is on a bucket, and the sides are closed, it will fill quicker than you think. I eventually made a bottom tined bucket for my grapple top. Big smiles when I did.

Carl

 

[jinman]

I agree that a shorter throw and shorter cylinder is better. Unless you plan on picking up sheets of paper, you don't need to have your grapple close completely. Opening wide to stay out of the way when not needed is more important than closing until the bottom touches the bucket.

 

[BotaBigot]

May be illusion, but from pics...appears grapple not contacting bucket lip allows cyl side to contact mounting bracket. Further ram travel bends rod. If you mod grapple to contact lip, extra travel will translate to force on upper lip mount...which may bend lip. Double-check geometry and choose cyl size carefully...

 

[J_J]

On some cyl, the rod end has a threaded shaft. The end piece can be adjusted for less or more length past the stroke limit.

So look for a cyl with a threaded end.

http://baileynet.com/hydraulics/bailey_hydraulics_other_products/?productcategory=1000061

Several of these cyl have adjustable yoke ends

http://baileynet.com/hydraulics/standard_hydraulic_cylinders/?productcategory=1000001

http://baileynet.com/hydraulics/bailey_hydraulics_other_products/?productcategory=1000024

You can also cut and weld on another yoke end

 

[Brad_Blazer]

OK, after mocking up a "simulated hydraulic cylinder" using PVC pipe and fittings, I've taken another full set of measurements. It looks like my last dilemma on this particular issue is "too long, or too short?"
My measurements suggest that to completely open the grapple, I need to have a cylinder that retracts to 16 1/2" and to fully extend the grapple (to the point where the cyinder has 1/4" to 1/2" clearance before it would contact the grapple) would be 24 1/2". The choices for cylinders I've found are either 15 1/2" retracted x 25 1/2" extended, or 13 1/2" retracted x 21 1/2" extended. The shorter one means that I have to add some more metal on the "spurs" I'm going to put on the grapple, (using some 1/4" plate and some 1/4" thick 2"x2" angle iron), but it's only about 2 extra inches of steel.
So, here's where my ignorance of hydraulics comes in, do I go for the longer cylinder and just make sure it has "positive stops" to keep it from getting lateral loads again, or do I go with a shorter cylinder that will neither fully open, or fully close the grapple. (Or is there another option, finding a "Goldilocks - just right" cylinder somewhere?)

All input appreciated.

Well, you're not a very good Goldilocks. These are a lot closer to "just right"

Hydraulic Cylinders 288-302 Detailed Information
Surplus Center - 1.5X8X1 DA HYD CYLINDER

 

[wdchyd]

Two choices Alpha if you want to keep the same center-to-center distance when retracted and shorten the stroke

purchase same cyl stroke and install a custom sleeve internally in the cyl between the gland and piston head to shorten stroke

or

purchase shorter stroke cyl and weld a spacer between the cyl base plate and cyl base cross tube

a lot cheaper than having a custom cyl made and the cyl integrity is not compromised

 

[Alpha Dog]

Well in case anyone's interested, I ended making all those measurments for about the 10th time, scratching my head a while, and going with the same type cylinder I originally had, (which I figured I'd use for another project if it wouldn't work) and followed that by some very careful testing. A little more exploration revealed that my "bolt-on" conversion was a big part of the problem, the 1/4" angle bracket that the tabs were attached to actually "flexed" several degrees when closing. The second issue, which was the grapple being able to enter the bucket, was "the straw that bent the cylinder's rod," (if I may mutilate a metaphor.) Since I have some very rudimentary skills in cutting and welding, and some scrap pieces of plate laying around, I made two "extensions" for the side of the grapple teeth, with teeth of their own, and tied these together with a piece of 1/4" square tubing, and a piece of plate across the end, essentially duplicating the last 6" of grapple, and after overlap, extending the grapple by about 2 1/2". Once through with that, and seeing that the "flex" allowed the whole system to bend forward to where the side of the cylinder almost contacted the web of the grapple again (by the way BotaBigot, it wasn't an illusion, that was the problem that started this lengthy thread), I just asked "Mr. Lincoln" to make a firm connection between the grapple and the bucket, front and top. It no longer "flexes" at all. Just to be safe, I then did a 1/4" "relief" at the point where the cylinder had hit the grapple before, even though all my tests showed I had nearly 1/2" of clearance now, I decided I'd add some "safety margin" in case there was any deformation of the grapple, bracket, or bucket as it "works in" after I finish the installation.
I appreciate all the suggestions, because they helped me think and work my way through the problem, but in reviewing what I need to do with the grapple, decided that I do need it to close, picking up yaupon and having part of it "pull through the teeth" as I raised the bucket kind of wasted a lot of time and effort (and diesel). Used it last weekend, worked great, and actually the extra "teeth" and extension allowed me to pick up stuff off the ground without getting off the tractor or cutting a big furrow in the soft ground, by coming in from "above" it, with the bucket fully tilted and just "pinching" it into the bucket. (Lazy, I know, but like any other practice stuff I do with a tractor, it's a skill builder, kind of like the video I saw recently of a guy using a small excavator to pick up glass bottles and stack them.) Practice makes "possible" there, I also once used an old 2 WD Leyland tractor and a box blade to do a lot of stuff they told me couldn't be done without a bulldozer, backhoe, and a few thousand dollars of my hard-earned cash.

Again, thanks to everyone, I really do appreciate all the suggestions and input.

 

[wdchyd]

We're interested....and glad everything worked out alright...

A couple of pics showing off your success in action would be a great way to finish the thread