Glowplug said:
There is a good chance the power of the tractor will push the grapple too much and cause it to be damaged (ie. bent to pieces). I guess with a battle between a powerful tractor, light-duty grapple, and stubborn brush the grapple loses.
There are several ways you can damage a grapple but I would not be concerned about damaging any grapple while going after brush with even a big CUT.
First, a big heavy tractor with lots of momentum driving a grapple through soil in "root grapple" mode could hit a big rock or stump and cause the whole tractor to come to a stop or worse. Worse would be hitting the immovable object other than dead center so the FEL/grapple was torqued to one side with considerable force. That might damage either the grapple or the FEL. Frankly I'd rather damage the grapple in that setting but I suspect it would be the FEL that suffered most.
Second, a monstrous capacity FEL (MUCH bigger than what Kubota sells for L or M class) could generate enough lifting force to distort grapple teeth. I see that WR Long rates their lighter duty grapple up to 3000lbs lift capacity so I don't think that is a practical issue for CUT owners but might be for big skid steers or big TLBs.
Third, you can do something that the grapple was not designed for such as place a lateral load on it. You could do that with a smaller tractor too so size is not a real issue there. Also, that same lateral load would just as likely injure the FEL itself.
I think that manufacturers are likely to recommend heavier duty (more expensive) options especially since they make the sale anyway and don't need to worry that you'll find a way to damage the goods. Realistically, cleaning up brush is such light duty work for any grapple that it is hard to imagine "breaking" a grapple while clearing brush unless the operator was abusive. Charging a stump like a bull to dislodge it will likely damage equipment unless you are driving a bulldozer. Bulldozers don't have FEL arms like tractors. They are short and stubby so cannot twist easily. I'd imagine that using a root grapple as a bulldozer might would likely hurt the FEL at least as likely as the light duty grapple.
Like most tools (hammers and bulldozers excepted) grapples are designed to be used properly. The proper use of a grapple is to grab on to something so that the FEL can lift/curl the object. No CUT FEL can curl or lift more than 3000lbs which is just not going to damage 3/8th x 4 inch tines ganged in groups of six or seven. Grapples, even those with weird names like "root grapple" are not designed to be used like 3PT subsoilers or bulldozers where there might be a sudden shock load from hitting a rock or stump. When using a root grapple to cut roots it is generally done just as you would dig with a bucket. You'd presumably put the bucket down then move forward rather than dropping the bucket while moving at high speed. I don't see how a grapple in subsurface mode would be injured any more than a bucket in the same situation. The momentum of a big CUT (eg orange M class) is probably not much more than double that of a smaller CUT (eg the other orange CK class) as the weight is not more than double (I cannot recall my physics right now but I recall momentum is a linear function). I have stalled my tractor on a number of occasions while driving the grapple against a stump with no harm done.
Having defended the light duty grapple, it is fair to add that I don't see any major downside to the heavier duty grapple for a CUT/FLE with a 2000lb plus lift capacity except acquisition cost. Even the added grapple weight will leave you with plenty of lift capacity as brush is simply not that heavy. Logs are heavy but CUT owners are not commercial operators trying to move three or four big logs at a time fifty times a day so that is not a practical concern either. I've never pulled a fence post but I imagine you'd essentially be trying to lift them out of the ground. Unless set in concrete
eek: ) you'd just need to overcome friction of the post walls to pull them straight up so I'd imagine the loss of 300-400lbs of lift capacity with a heavier grapple would not be important there either.
To reiterate my main points: heavy duty grapples are built for big skid steers. I doubt even the biggest CUT FEL requires the heavier duty construction and the major downside to consider is whether the added weight will interfer with your intended use.
