My first tractor grapple

[MarcusCarr]

Spurred on my the many homemade grapples that I have seen here, I have decided to attempt one.

I have attached a picture of my prototype and would appreciate any comments that you may have.

One issue I am having is the selection of a cylinder. I would like to find one that is 18" pin to pin in the extended position and about 10" in the closed position. I assume I need a double action piston so I can keep it in the open position? Any idea where I can get this? a link to the cylinder would be very helpful.

I am breaking the project into two parts...the grapple/piston and the hydraulics/hoses. Currently, just trying to focus on the grapple piston part.

 

[jdgreg]

Nice looking model. I got a cylinder off ebay pretty cheap, for a 3ph grapple I built. Might give that a shot.

If you havent already done it, now that you have what appears to be a working model, clamp it onto your bucket and make sure the complete range of motion is what you want. I would recommend making particular attention to full open and full closed, which be impacted by the length/throw of your cylinder. I adjusted my ATI grapple so that at full cylinder extension the forks were sitting on the bucket cutting bar about 1/2" back, and made sure that at full retraction the grapple forks are open wide enough to not interfere with getting the bucket/forks under the brush pile. I hope all this makes sense.

Good luck, and have fun. /forums/images/graemlins/cool.gif

 

[MadReferee]

You are not going to find a cylinder that has an 8" stroke and a 10" retracted length anywhere. I suppose you can have one custom built but it isn't going to be cheap.

Typically, a tie rod cylinder with a 4" stroke will have a 14.5" retracted length as a minimum. An 8" stroke cylinder is getting upwards of 18" to 20" retracted.

A welded cylinder will get your retracted length down to 11" for a 4" stroke and 15" for an 8" stroke but will cost almost twice what a tie rod cylinder will cost.

I suggest you get a catalog from Surplus Center and take a look at what is commonly available out there in the Prince and Chief lines of cylinders.

BTW, the cylinders typically used on the small grapples (ie the Thumb) are 6" stroke with 16" retracted length, double acting, tie rod cylinders.

 

[1948berg]

Buy a hydraulid top link. Comes in different sizes. Can be used to other purposes as well. Easy to fit.

 

[MadReferee]

</font><font color="blue" class="small">( Buy a hydraulid top link. Comes in different sizes. Can be used to other purposes as well. Easy to fit. )</font>

A hydraulic top link is nothing more that a standard size welded cylinder. I don't see how one would meet his design criteria any more than a regular tie rod cylinder. And besides, all he needs is a cylinder with a 2" bore. Toplinks usually have a 3" bore and are way more expensive.

My advise to the original poster is to design around a commonly available cylinder. The 6" stroke x 2" bore Chief seems to be the most common.

 

[MarcusCarr]

If I can get my hole distances correct...does this cylinder look like it would work for a grapple?

Grapple Cylinder?

 

[MadReferee]

That would work but it's a little light on oomph. By the time you buy the adapters to go from the SAE 4 ports to 1/4" or 3/8" NPT you might as well go with the 2" bore x 8" stroke Chief (part # 9-4300-08-S) It's $20 more but less hassle and you might even be able to shorten the retracted length by using a different end on the rod.

 

[MarcusCarr]

Excellent advice, I will go with that one instead.

Do you think that 1/2"x3" steel would be strong enough for this?

My tractor is a 28hp Mitsubishi with a bucket that is 47.24 inches wide.

Thanks,
Marcus

 

[MadReferee]

</font><font color="blue" class="small">( Do you think that 1/2"x3" steel would be strong enough for this? )</font>

The grapple's on eBay (ie. the Thumb) have the arms made from 3/8" plate and the tubing for braces has a wall thickness of 1/4". Using 1/2" for this application would be overkill.

 

[Highbeam]

Unless you just really like making things, you ought to at least price a couple versions like "the thumb". Just materials cost will about buy you one.