I have the "skid steer" type attachment on two loaders, but, both skid steer, and JD quick attach work similarly.

I think the failure that you have encountered is due to "back dragging",,
You may not intentionally do it, but, it can happen.

Virtually all materials are stronger in compression, as compared to tension,
back dragging causes undue stress on the pin connection that failed as the joint is put in cantilever tension.
(cantilever is the other baddy,, design, IMHO)

Actually, the failure may have started by back dragging with the bucket, then failed with the grapple.

I may be TOTALLY off base, but, that is my take on the issue,,,,,,,,,,,

 

Back dragging. Never considered how much this would stress the quick attach assemblies right at the point of the lynch pins but it does make sense.

 

I think the failure that you have encountered is due to "back dragging",,
You may not intentionally do it, but, it can happen.

Back dragging.

Not the issue here...just the design of these "mechanical" grapples.


Take a look at this quick video to see the issue:

 

Those carriers were fabricated as opposed to cast. I might have been inclined to cut off the bad tabs and fabricate new ones before coughing up $1500+.

It's interesting that Westendorf hasn't modified their design and Deere is selling an identical product with these known issues.

 

Not the issue here...just the design of these "mechanical" grapples.


Take a look at this quick video to see the issue:
,,,,,,,,,,,,,,,,,,,,

Yep, here is another video,, right at 6 minutes, the cylinder that tilts the bucket looks like it is trying to push that pin straight ahead,,

I guess that is an attachment that is off the wish list,,,,,,,,,,,,,,,,,

 

I guess that is an attachment that is off the wish list,,,,,,,,,,,,,,,,,

No free lunch!

 

I have the same mechanical grapple and the same failure happened to my holders 120R Bucket Holders broken W50722 and W50723
Both left and right holders were completely replaced under warranty, surprisingly! I'm not a huge fan of the mechanical grapple but it has served the purpose for moving over an acre worth of cut trees.

 

I started this discussion on another thread, but decided it needs it's own post.

The hurricane blew through and we have a lot of trees down, so I got a MG20F Mechanical grapple for my 2032r. I moved a lot of wood with it but as warned, it broke my loader. Specifically, the right hand bucket holder (P/N W50722). It also bent the lynch pins.

I had lost one of the lynch pins (before I broke the holder), so I put in a 7/16 bolt. This snapped after a short time. So this might be one solution: sacrifice a $1.00 bolt instead of a $244 bucket holder.

I think the problem occurs during the clamping process. If you clamp down too hard, it puts undue stress on the bucket holders.

I had an Idea to reinforce the holder by drilling a hole through the grapple and supporting it with a 1/2 inch bolt and a thich bar (see picture with red oval). Of course, this would defeat the purpose of the "quick-disconnect". But the problem I've found with quick-disconnects that they often come disconnected a little TOO quick. req

I sent a customer support request off to John Deere, which they will probably pat me on the head and tell me it's all my fault. View attachment 924227 View attachment 924228 View attachment 924230

Mechanical grapples on anything bigger than a 1 series or 2025R will destroy your loader. They’re not much cheaper than hydraulic ones either. Yes, there’s the cost of the 3rd function upgrade to the tractor, but that’s a one time cost. Get the hydraulic setup and you will not regret it. You also have superior movement capabilities to boot. As they say “Buy once, cry once “.

 

So does a hydraulic grapple connect to the tractor different than a mechanical grapple?

 

Actually, the failure may have started by back dragging with the bucket, then failed with the grapple.

I may be TOTALLY off base, but, that is my take on the issue

You are. Back dragging is not the issue

Not the issue here...just the design of these "mechanical" grapples.

^^^^^ This is the issue.

I back drag with my Artillian grapple all the time.

 

Kenny,

I can't begin to count the number of times you and I have told people these grapples are useless. I guess no one's listening. two years ago, I broke a hydraulic fitting on my AV20F, and that's the extent of the damage after almost 4 years of heavy-duty work. Many people specifically state the cost savings associated with a mechanical grapple. I guess they forget to add in for the broken hardware.`

 

I agree.

 

The problem could be easily solved by drilling a hole in the grapple and reinforcing it with a 1/2" bolt. But that would probably void the warranty. Think I'll talk to my JD guy about it.

 

It's the same force as back dragging or pushing down on the bucket edge trying to pull the pin through the hole but many times worse because you have the hydraulics pushing with a lot more leverage and mechanical advantage. backdragging you only have the weight/power of the tractor pulling the pins through.

 

Well, now I blew out a hydraulic hose. It goes to one of the cylinders that operates the mechanical grapple. I guess it puts undue stress on the hydraulics, too. I'm not using this grapple any more. It's caused too much damage to my tractor. I'm gonna sell it and get some pallet forks or a hydraulic grapple.
Anybody know any good pallet forks that would go on a 2032r? The only thing that's coming up on John Deere site is Frontier and after this MG20F debacle, I'd as soon buy something from the Chinese commies.

 

Well, now I blew out a hydraulic hose. It goes to one of the cylinders that operates the mechanical grapple. I guess it puts undue stress on the hydraulics, too. I'm not using this grapple any more. It's caused too much damage to my tractor. I'm gonna sell it and get some pallet forks or a hydraulic grapple.
Anybody know any good pallet forks that would go on a 2032r? The only thing that's coming up on John Deere site is Frontier and after this MG20F debacle, I'd as soon buy something from the Chinese commies.

John Deere AP11F, or a host of options on the internet. I'd stay with a unit that has a capacity of 1500# or 2000# to keep the weight down. As for fork length, I'd go 42" with a 2 series.

 

The JD forks are very good forks. Tough as nails and there is a model for every machine.

 

John Deere AP11F Is made by Frontier.

Frontier doesn't "make" anything. They contract vendors like Woods and others to make implements for them.

The mechanical grapple you bought is most likely made by Westendorf and is basically the same as the "Brush Crusher" mechanical grapple they sell under their own name.

I am not sure who makes the pallet forks for Frontier. I haven't heard of any failures or issues with Frontier pallet forks.

You didn't listen when several told you not to get a mechanical grapple. If you want to strike out twice, most of your Amazon hits for pallet forks will be Titan.

 

My JD guy says he has some Frontier pallet forks for $1400. Hopefully I can sell the grapple for about $2000 and at least break even, maybe even come out ahead.

 

Glad i came across this post. I got a frontier mechanical grapple in March, have used it to clean up about 6 acres so far with many more to go. I have not noticed any issues or even had a pin bend, but i will be keeping an eye out. thanks for the info.

 

Kenny,
I actually went to my dealer to look at this out of curiosity. My now retired engineering mind found a simple way to "help" with this issue.

Note that the lower jaw contact points are adjusted low in almost every case, allowing the lower jaw to open as wide as possible. Doing this places an extreme pulling force on the pin, which eventually leads to failure.

By adjusting the grapple and placing the boom stops in their highest position the majority of the force is now transferred to the pins downward. This helps to eliminate the pulling force on the pin associated with the extreme opening of the grapple jaws. You can't change physics.

 

Note that the lower jaw contact points are adjusted low in almost every case, allowing the lower jaw to open as wide as possible. Doing this places an extreme pulling force on the pin, which eventually leads to failure.

By adjusting the grapple and placing the boom stops in their highest position the majority of the force is now transferred to the pins downward. This helps to eliminate the pulling force on the pin associated with the extreme opening of the grapple jaws. You can't change physics.

The Brushcrusher has adjustments. Unfortunately for the Frontier MG20F, it has no adjustment for the lower jaw position. Its boom stop is fixed, so the jaw hangs open very wide unless we do a modification to it. I posted in another thread on this issue with a rough free body diagram of the exact thing you are talking about and I 100% agree with you on the forces and their directions. A force directed perpendicular to the lower jaw tines pulls the pins with a force roughly 2.5 times that (rough scaled dimensions still, I haven't taken a tape measure to it).
I would like to weld additional steel to the lower jaw so that it is not allowed to fall much below horizontal, but still contacts the same location on the underside of the loader arms. I'm confident this would eliminate the problem. I'd lose a bit of opening grapple distance but it appears there would still be plenty of room with the top jaw curling open.

 

FWIW, I've never had to "re-engineer" my grapple.

A good design is what I paid for.