Grapple cylinders

[mwb]

Here a link to the grapple I made to work with my pallet forks. This is probably the ultimate brush grapple - light weight and very hungry (big capacity).

I would still like a 'real' grapple but this one was cheap to build and works awesome for brush, so-so for rocks.

http://www.tractorbynet.com/forums/attachments/190364-homemade-grapple-pics-video.html

 

[easygo]

Why do humans have only one thumb on each hand? Wouldn't it be better to have two so we could pick up irregular objects?:laughing:

Well. If you want to split hairs ... bringing a human thumb into it is not an accurate idea. It would be a better way to look at it as your four fingers opposing the palm of your hand. That is what a grapple really represents. Your palm being the lower part of the grapple and the fingers are operated independently as the jaws.

Pick up a stick and each finger closes down the same amount. Pick up a handful of larger pebbles and it is likely that each finger will close slightly different amount. Then tape your index and middle fingers and your ring and pinky fingers together. That will give the two jaw grapple and then tape them up all up to represent the single jaw. See how many pebbles you can pick up with each method.

Make the same idea out of steel and operate the fingers by hydraulic cylinders will become a grapple. Engineering and REASONABLE NEED decides the reasonable number of opposing jaws.

If you really want to stick the thumb in there, the accurate way is to tape up all your fingers and render them immobile. Bring your thumb down onto them and you have a single jaw grapple. Try to pick up the same rocks ... then imagine if you had another thumb...

 

[Redbug]

SLHawkins...Help me understand this...on the 2 jaws vs the 1 jaw...the plumbing is about the same? Input and output lines to your valve, from the valve, and both lines go to both jaws? Seems you would need a third line to operate a second jaw. Or are they in parallel, where the same input and outputs are tee'd and going to each jaw after your valve?

 

[kennyd]

SLHawkins...Help me understand this...on the 2 jaws vs the 1 jaw...the plumbing is about the same? Input and output lines to your valve, from the valve, and both lines go to both jaws? Seems you would need a third line to operate a second jaw. Or are they in parallel, where the same input and outputs are tee'd and going to each jaw after your valve?

The two cylinders are plumbed in parallel just like your two lift cylinder and two cylinders are.

 

[J_J]

Although both cyl get fluid at the same time, the cyl with the less resistance will move first. The two cyl will apply the same force when the pressure is maxed out.

The one cyl may clamp down on the teeth, or something solid, and the other cyl will clamp as much as you apply hyd force.

If you install a hyd gage, you can watch the pressure used to operate the grapple or any other function in the hyd system.

A lot of people think you are applying pressure, but the pressure is only developed when the cyl does work. You are applying hyd flow, which determines the speed of operation.

 

[SLHawkins]

SLHawkins...Help me understand this...on the 2 jaws vs the 1 jaw...the plumbing is about the same? Input and output lines to your valve, from the valve, and both lines go to both jaws? Seems you would need a third line to operate a second jaw. Or are they in parallel, where the same input and outputs are tee'd and going to each jaw after your valve?

Redbug,
See JJ's and Kennyd's responses. Yes, the fluid (pressure) for both jaws come from the same valve. The lines are are tee'd after the connection on the grapple itself. As stated by kennyd, your curl cylinders are plumbed the same way. Disconnect your curl cylinders from your bucket and you will find that they will extend and rectract separately. Same principle with the dual jaws.

Hawk

 

[Redbug]

Oh, I see now. That's really pretty nifty then since they will even out pressure wise no matter what odd size object you grasp with only one button or switch. I wondered about that. So...not much mind work involved since it is only one switch...

 

[SLHawkins]

Oh, I see now. That's really pretty nifty then since they will even out pressure wise no matter what odd size object you grasp with only one button or switch. I wondered about that. So...not much mind work involved since it is only one switch...

Yep, you got it:thumbsup:

Is that a 4-in-1 bucket on the tractor in your profile picture? If so, then you already have a 3rd function valve and are good to go!

 

[Redbug]

Yes, Hawk...I have a 4in1 and also a root grapple...both made by WRLong. I also have the WRLong electric over hyd valve. It's a great setup.

 

[dex3361]

yeah, width ways. Here some pics.

What did you cut the metal with? Nice looking fab work.:thumbsup: