5 months ago my grapple bucket was coming off. I took the rosebud to the bottom of the bucket and heated/hammered back to square. It hasn't come off until today. The work I did looks good. When I have the bucket tilted slightly down and push down on the front it pops right off the quick attach. I spilled some hydraulic oil on it and that's when it started. I know that's not the problem, it's only exasperating it. Here are some pics. Any ideas?
If it's tight fitting of the coupler then the pins are pushing up to far means there wear or something damaged on the locking mechanism. I'd nearly bet money the grapple is loose on the hitch.
Pic
Hanging free
Slight downward pressure
Pops right off
Gap on left side. It slides back and forth about 1/2 "
Post #6 upper piece left side looks like it's cracked off. right side shows good weld.
I can't see anything cracked. Here is another picture of the left side
Here is a picture of the lock downs.
How's the taper on your wedge pin look? Should be a nice flat slope. Yours looks pretty worn where it engages the attachment. Also check where the wedge pin hits the attachment. I just finished welding up that spot on a bucket that was missing a good 1/2" of material there from wear & tear.
https://wiki.opensourceecology.org/images/f/f6/Sae_j2513.pdf make a cardboard or plywood template of the above, and use it to check your top & bottom angles as well as fit.
What's the condition of your overcenter springs? Those wedge pins should never have play, the spring should always drive the pin tighter.
I'm not sure how it looks relative to a new one. I've been using the hell out of my stump bucket lately and it never comes off.
So if I hammer on the bottom of the pins and there is no play the springs are good?
That looks like a good start.
What I mean to say is that the wefldge pins should be under constant tension to always tighten up. Unless they're at or beyond their mechanical limits.
OK. My lock down levers I can lock down with a finger. They are very well greased but maybe not enough spring pressure?
Should probably need more than finger pressure. It’s kinda annoying that your mechanism parts are buried in the frame of the quick attach. Might have to take the quick attach off to get a good look at the springs in there. Should be two springs, one for pretensioning the handle so it doesn’t automatically lower itself when you have thing detached, and another bigger spring that keeps tension on the wedge pin.
I measured this distance on my stump bucket and it was around 15 inches. My grapple is 16 inches. This pictures shows the bottom of the grapple bucket.
I am going to cut this weld and the other weld on the other side, bend the whole bottom plate down to around 15 inches and reweld it. Sound like a plan?
Follow the template/dimensions.
If I read the diagram correctly it is 15 7/8. Right about where I am shooting for.
...and the correct angles.
Most likely need to cut the whole bottom piece off and move it. The correct angle is critical
I've cut it and have been fine tuning it to get a proper fit. I have my levers up as far as they will stay. Are my pins in a normal position here or should they be flush?
while you're going through all this trouble, inspect your wedge pins. Here's a picture of what new ones look like for my bobcat. Mine stick out about the same from the quick attach frame when they're fully retracted.
Great pic. Thanks. I'll check them in the morning.
I have had this problem before with wear on the top of the coupler plate on 299s being the issue. It is softer metal that wears. I have done weld buildup and grind to profile with success.
I can identify this wear if you post a side profile picture of the top of the coupler plate.
Great. I'll post it up in the morning.
Here it is.
Other side.
My pins look ok. Fully locked down they are a little over an inch. Is that about right?
Congratulations you have wear. The angled area on top should be taller. When new the angled area is tall enough that it runs across the full thickness of the plate I believe. Make a template of the angle. None of the slope angles should be changed. Weld build up and grind to profile. My guess is you need to add close to 3/8 of an inch in height. Hook up to a good attachment push on ground and measure the gap between the top of the coupler plate and the attachment. This should confirm about how much build up you need. Not all attachments have the same fit. You may want to check with multiple attachments. If you need to find a new machine and make a templet to better understand do so. Maybe you can get a member to post a profile pic same as you did for a new machine to show the difference. Make sure to preheat and keep the plate hot while welding to prevent warpage followed by post heating to get even cooling. I preheated to 200F and kept Interpass to 300F. I used 7018 5/16 and 3/16 rod with success. I welded a piece of flat bar across the front to help with warping during welding. I may have wrapped the plate in home house rolled insulation to get even cooling after welding and post weld heating. All done while still attached to machine. FYI bobcat machines do not wear in this area at all. I have welded cracks on bobcat couplers plates though in extreme applications. I can't remember for sure. Don't forget to disconnect battery before welding.
I posted a link to the correct dimensions, easy to simply make a cardboard template with a protractor and square. If you copy from a new machine, you still don't now where in the tolerance band that was made. The linked shows the complete over & under. EDIT: My neighboring weld shop started making QC plates....."We measured one we got from a Bobcat". And all 3 I bought from them are loose. I'll wager that machine/bucket they copied was at the top end of the tolerance band, and they vary a wee bit more + & - as they build them. So many (or all of them) that they build are too high, and are loose.
I keep staring at that drawing. I get more confused the longer I look at it.
Is there a drawing for the CAT mounting plate--not the implement? I can probably do the cardboard template but it would be easier if there was a drawing already done.
I talked to CAT. Their drawing says the top angle is 40 degrees. The length is 353.7mm from the top of the top angle to the center of the pin--squared to the side of the plate.
It looks like I have 3/16 inches of wear to build up. Not as much as I thought.
Actually it is closer to 5/16.
I got it welded up. It is a lot tighter now. Thanks to everyone for the help.