mini ex thumb

[J_J]

bcantell,

Is the thumb mounting plate one piece, or two? The reason I ask, is that thumbs usually are at the max extend at about 90 degrees to the boom. Your thumb goes toward the bucket much than most. My observation on the thumb is that there is about a 5 to 1 push force, and if the bucket was forced all the way against the thumb, that force would be multiplied about 5 times, and over power the thumb. After doing this many times, the fluid will find a channel and pass to the other side of the piston. This could set up a leaking piston. If that is a one piece mount, it is what it is, and they apparently wanted you to mount it that way. If it is one piece, then the option to install the base mount is your decision. When you see thumbs with out a cyl, otherwise mounted solid, they are usually 90 degrees to the boom. Maybe for a reason. I would expect the cyl mount to be about half way on the thumb, or lower.

 

[SpecElim]

Nice to have someone else out there with an EC-25! I have had one for the last 6 (maybe 7?) years. I have been looking for a thumb for it that is relatively inexpensive...Where did you get yours?...

I don't know much about the hydraulics...just that it will run a small bush hog (Which I want to build).

If you have any questions about your new machine feel free to ask!...2200 hours and this one's still running like a top!

If you've ever run a bobcat they really don't compare (at least the 337/341 models). Those will dig circles around the 25...but they are bigger. We had one of each but...Unfortunately... had to get rid of them.

Matt.

 

[wdchyd]

Unfortunately, a crossover relief will not work on a single rod cylinder. You can limit the force that the cylinder can generate with this valve, but it will not relieve the thumb cylinder when it is over powered by the bucket or the dipper.

You're right, only because displacement on both sides of the cyl is different....but theoretically if the displ was the same (as two cyl setup) it would relieve itself between the two ports.....I didn't think of that but thats why it would work on "two cyl setup or hyd motor setup".....

 

[wdchyd]

bcantell,

Is the thumb mounting plate one piece, or two? The reason I ask, is that thumbs usually are at the max extend at about 90 degrees to the boom. Your thumb goes toward the bucket much than most. My observation on the thumb is that there is about a 5 to 1 push force, and if the bucket was forced all the way against the thumb, that force would be multiplied about 5 times, and over power the thumb. After doing this many times, the fluid will find a channel and pass to the other side of the piston. This could set up a leaking piston. If that is a one piece mount, it is what it is, and they apparently wanted you to mount it that way. If it is one piece, then the option to install the base mount is your decision. When you see thumbs with out a cyl, otherwise mounted solid, they are usually 90 degrees to the boom. Maybe for a reason. I would expect the cyl mount to be about half way on the thumb, or lower.

Yes, leverage plays a major role here!!!! It's always advisable to grab with the thumb and not the bucket cyl (This should be the rule /not the exception) as the bucket cyl always overpowers the thumb.....

 

[bcantell]

JJ The thumb was installed (one piece) so that when retracted it wouldn't hit the arm. It seems to be a little large for the Volvo, but I took the advice from the company that sold me the machine. Time was a factor, plus I was new to this, so I just had them order the thumb. I should have taken the time to do more research. I like the thumb, it is "beefy" and the cylnder is large. The thumb will move the bucket. SpecElim, the thumb is made by TAG and it's wasn't cheap, I think I paid $1600.00, but it is well built, nice welds, large cylinder (3" round x 15" long) and 1/2 steel, solid mounting plate, solid web between two teeth. It cost about anther $400.00 for the hoses and welding. Don't get me wrong here, this thumb makes the machine, which is a really nice machine to begine with.