110 tlb thumb question?

[mechatgsk]

Hello, I have recently installed my thumb kit from John Deere that I purchased with the tractor in 2011. I finally got to use it yesterday and it worked fine. I used it to pick up a few logs about 8 to 10 inches in diameter and 4 to 6 feet long. After I was finished I was looking over the thumb and welded brackets. (1) one that attaches the cylinder to dipperstick (2) the thumb contact plate on dipperstick. Now here on the thumb contact plate I noticed it was bent inward slightly, as well as the dipperstick. Now when I say slightly I mean approximately 0.025. I put a machined straight edge across the top of the 1/4 thick by 2"x 4" inch weld on contact plate. I installed the thumb exactly as John Deere said to in the instructions. I also know the thumb will contact this plate each time it is retracted and this thumb is heavy. No, I have not tried to slam the thumb into the contact plate but sometimes it did move at a faster speed than I would like. I was not aware this may happen. I do know that John Deere revised this contact plate from two plates (1/4 inch lower plate similar to cylinder plate and a 3/4" top block) to the single 1/4 inch thick by 2"x 4" plate that I received with my kit. I do think the contact plate should extend far enough across dipperstick to rest on top of the verticle plates of dipperstick and not between them as it is now. And maybe duplicate the original design?
I was wondering if anyone had experienced this?

Thanks,
mechatgsk

 

[frencht]

I do think the contact plate should extend far enough across dipperstick to rest on top of the verticle plates of dipperstick and not between them as it is now. And maybe duplicate the original design?
I was wondering if anyone had experienced this?

Thanks,
mechatgsk

Mechatgsk,
I bought a used 110 which has the 7th function but has never had a thumb attached. I think your concern is valid based on the rather large indentation on my dipperstick in the area where the thumb would be retracted. I suspect a large rock or other solid object was in the bucket when the bucket was curled too tight, thereby, causing the bottom dipperstick plate to indent.

Like you, I'm anxious to hear what other thumb owners have to say about how there's is setup.

frencht

 

[sdkubota]

Thumbs are notorious for getting bent from the operator applying to much pressure against something.

 

[mechatgsk]

Hello sdkubota, I'm sorry you did not understand the question. The thumb is not getting bent, it's the thumb retract plate and dipperstick.

Mechatgsk

 

[murphy1244]

Maybe cylinder too short?

 

[mechatgsk]

Hello frencht, I added some photos for all to see what I am talking about. Note: This small indentation happened after only 2 hours of operation and I only used the thumb 5 or 6 times.

 

[mechatgsk]

Hi murphy1244, the cylinder is the one that John Deere sent with thumb kit. It is the correct part. I think it is a combination of two things. One...the new design of the retract plate is too small (length and width) and 2nd..the contact points on the thumb are too close together causing them to touch in the middle of contact plate. I feel if the thumb contact points were spaced apart to about 3.750 to 4.0 inches and a larger contact plate fabricated this would help tremendously. Another thing to remember is the outside measurment of the two verticle plates of the dipperstick are set at 4-3/8". The inner face plate of dipperstick is just slightly over 5.0" wide and also onlt 3/16" thick material. Then you have a small contact plate that is 1/4" thick by 2"x 4"?

Mechatgsk

 

[Gale Hawkins]

That is interesting. We have a manual thumb on the JD 310B so that is not a possible but I can bend the hollow pin It keeps it in the position that I place it manually so I am working to learn to manually control the pressure. Using a thumb without damaging the hoe is harder than I expected.

I take unlike your other cylinders the control valve does not slow it and and stop it automatically at the end of the stroke preventing a hard high speed contact?

 

[AKfish]

Ok.... now I'm gonna be polite and take your concerns to heart. Really! I'm gonna try my best! :thumbsup: Twenty-five thousandths? I saw the gap. And you're fairly certain (and you checked) that the deformation was not there prior to using the thumb?

It's not the result of heat warpage from the welding process?

I would offer a perspective on what's likely to occur as you use your backhoe and thumb in the future. That gap is most likely to be anywhere from 1/8" to 3/16" by the time you have 1,000 hours on your machine. Yup...

Now, if you'd like to avoid that situation - I can offer you a freight quote - one way to my house.

AKfish

 

[AKfish]

I take unlike your other cylinders the control valve does not slow it and and stop it automatically at the end of the stroke preventing a hard high speed contact?

It clanks... sometimes at the end of the cylinder stroke. As the pins begin to wear with hours of use; there's even more "slop" and the motion of the thumb (and every other moving component on the hoe and loader, etc.) does not conform to the same "stop and go" extension limits as when new.

We all note that same operational characteristics with machines as they get worn out...

By the way; the thumb cylinder operational pressure is 2,500psi and the curl function on the bucket is 3,000psi. So, with a clamped load as you curl the bucket the thumb will slowly yield without blowing a seal in the thumb cylinder or blowing a hose.

AKfish