Grapple Failure

[94BULLITT]

I agree. The first thing I would do is drill a 1/4 inch hole in that top tubing and see how thick it is. If it is still 1/8. then reinforce it to distribute the stress and carry on.

James, look at the cylinder mount on it then compare it to your grapple. The Wildkat looks like a poor design even though it is made out of 3/8''.

 

[k0ua]

James, look at the cylinder mount on it then compare it to your grapple. The Wildkat looks like a poor design even though it is made out of 3/8''.

I did that very thing 2 days ago.. and noted the differences in how the cylinder was mounted.

 

[Coyote machine]

For discussion sake, why not install a crossover valve in the hydraulic cylinder's circuit, set it to where inadvertent clamping down on a load would not create forces large enough to result in damage to the grapple? This would allow use of the current design; though going to 1/4" stock tubing would likely effect the same result, at possibly lower overall cost increase. The best might be to do both, and likely eliminate both self destruction of the 1/8" material AND less potential failure in use with larger weight and HP tractors. End result, happier users, more sales, better reputation, etc.
What say you 'herd' :confused3: ?

 

[TomSeller]

Agree 100%-although there are many whom have posted on this subject that insist its an over application of hydraulics.

In the previous thread (from 2 years ago) referenced in this thread it was mentioned that the cause of failure had to do with pushing with the lid. In this thread the cause of failure had to do with clamping down with the hydraulics if I understand correctly.

 

[ishiboo]

IMO using thin wall tube for that area is not really the problem, but the design itself. There grapple mount should be two plates (1/4?) that are welded to both the top tube and travel down to the bottom tube.

 

[jmc]

Yep. Looks like saving $12-15 bucks per grapple is more important to some companies than quality.

If he did that cost comparison with the steel prices companies pay for a few thousand pounds instead of a few feet, their cost savings would seem even less defendable. Also, some of the steel service centers have price schedules that discount according to ALL the steel you buy annually, not just that few thousand pound order.

 

[bhh]

Because the FELs have a rather small payload capacity on these smaller compact tractors, let's remember there is a real need to NOT over-design them. That is as much a reason why people choose these 48" "economy models" than just saving a couple hundred dollars. That was the case with me personally. I attempted to balance strength with weight but cost is obviously part of the equation or I'd have a titanium grapple or whatever. It's a real balancing act between weight and strength and some companies are going to do a better job than others.

I can actually understand why thinner walled steel may have been used to shave down some weight at some point but if that decision leads to an abnormally high failure rate, then it obviously needs to be corrected. What we don't know though is how many of these units have been sold and how many had/have problems. We have two on this thread but those could be due as much to bad workmanship than to a design flaw and the actual failure rate could be quite low. I'm not saying I believe that is the case but I'm also trying to have a balanced view through all of this.

If 2 out of 100 fail, is that bad? 1 out of 100? 5? Everyone is going to have a different number and I'm sure they could achieve a zero fail rate but what would be the weight penalty we would have to endure as a result? As long as the company stands behind these failures and does right by the customers, a 1-2% failure rate might actually mean that the grapples are designed appropriately for their use. Just a thought.

 

[IslandTractor]

Because the FELs have a rather small payload capacity on these smaller compact tractors, let's remember there is a real need to NOT over-design them. That is as much a reason why people choose these 48" "economy models" than just saving a couple hundred dollars. That was the case with me personally. I attempted to balance strength with weight but cost is obviously part of the equation or I'd have a titanium grapple or whatever. It's a real balancing act between weight and strength and some companies are going to do a better job than others. I can actually understand why thinner walled steel may have been used to shave down some weight at some point but if that decision leads to an abnormally high failure rate, then it obviously needs to be corrected. What we don't know though is how many of these units have been sold and how many had/have problems. We have two on this thread but those could be due as much to bad workmanship than to a design flaw and the actual failure rate could be quite low. I'm not saying I believe that is the case but I'm also trying to have a balanced view through all of this. If 2 out of 100 fail, is that bad? 1 out of 100? 5? Everyone is going to have a different number and I'm sure they could achieve a zero fail rate but what would be the weight penalty we would have to endure as a result? As long as the company stands behind these failures and does right by the customers, a 1-2% failure rate might actually mean that the grapples are designed appropriately for their use. Just a thought.

The proper way to make a lighter grapple is to use high strength steel rather than lower gauge mild steel. That is essentially what EA did with their new light duty grapple. The other consideration, if you intend to stick with lower gauge mild steel tube is to engineer it properly. Not only does Wildkat use 1/8" tube but they also use a higher cylinder tower which puts more leverage force on the base. Putting in some extra support at the predictable stress points would work but increase cost due to additional welding. Yes, some builders will choose the HF strategy and just build it cheaper and cheaper until it breaks, but I for one would like to know that I am buying an HF quality implement. Is that what we should expect from Wildkat?

I don't think any of us know the exact failure rate of these 1/8" top tube grapples. I would guess that all of these 1/8" grapples would fail at the same spot if used aggressively or at the point when a predictable accident puts a bit more stress on that rear cylinder tower. Probably not likely if the tractor is a BX or B size just moving brush piles but for someone with an L size tractor digging and moving stumps and trees etc the safety margin is slim. I don't recall anyone with a 1/4" tube grapple having this same issue despite using this general light duty grapple type on tractors as big as M59s.

 

[blueriver]

Okay .. Was this or was this not the economy model? Did the OP know this when the order was placed?

I'm thinking out loud here .. A choice was made when the order was placed???

 

[murphy1244]

Okay .. Was this or was this not the economy model? Did the OP know this when the order was placed?

I'm thinking out loud here .. A choice was made when the order was placed???

Since everyone here knows about it I don't think they would buy it now. I sure won't.