Differences in Quick Attach Bucket Mounts?

[Slippy]

Yes. You can see how far the pins come through the hole in the implement. I don't think with that much pin comming through there will be much risk of it "popping" out when back dragging. I suppose that problem could occure for two reasons, first, there is not enough pin protruding through the implement hole, and second, the pin is dragging on the ground and causing the pin to push back up through the hole.

The rectangle frame of the QA plate on the implement keeps the QA "feet" on the loader from moving down, and side to side. There has to be a gate way or door way for the foot to get inside the frame, and that occurs from the bottom. As you pull up to the implement, you place the top of the "foot" on the loader in the upper ^ part of the frame. As you lift, the bottom of the implement will contact the bottom of the foot. At this point, the pins are engaged, which is what keeps it from comming off. But, the load point is in the top (^) of the QA frame plate and the QA loader foot. As long as there is enough pin comming through to keep it from lifting off as you back up, you should be ok. All of the forward motion, digging motion will push at the bottom of the foot and the bracket. Thats why I don't think it makes much difference where the pin comes through or the hole location as long as you have enough pin protrusion.

 

[SPYDERLK]

On mine the pins cannot pop back up if the egagement lever arms are all the way down. They force the pin to full extension and then overcenter slightly to a hard stop. A spring serves to detent each lever into the engaged/pin forced position. The only way the pin would push out of the slot would be to bend something unless the lever is for some reason not in the overcenter position.
larry

 

[patrick_g]

PS - how do you get to claim "dumb" if you retired at 56 as a mechanical engineer (from a working stiff ME)... You must have done something right.

Hazmat, I resemble that remark (retiring at 56) but there was as much luck involved as anything else. That and because I was quite proactive in the fact that I wrote a detailed economic analysis that conclusively demonstrated that my job should be abolished. A side effect of my job being abolished, since I had over 20 years service, was eligibility for early retirement.

I like my Kubota Quick Attach but would be happier if there were more standardization, even if it had cost a bit more. Access to lots more implements would be worth a little extra for the cost of the loader.

I have lost the pins out of my guick attach several times. I don't always find them. The keepers (anything but a bolt with nylock or similar) are easily lost when digging in gravel, dirt, or fussing with brush. Then the pin works its way out. Once the FEL-implement combination has been used fairly hard the pins don't just glide into and out of the holes so easily and a hammer may be required. Sometimes you can manually displace the bucket or hay spike or pallet forks or whatever a bit and with the other hand move the pin while the implement is in this "neutral state."

From the little bobcat experience I have I haven't noticed implement swaping to be difficult. Larger Kubotas have an easier arrangement than my L series.

Pat

 

[Dougster]

Yes. You can see how far the pins come through the hole in the implement. I don't think with that much pin comming through there will be much risk of it "popping" out when back dragging. I suppose that problem could occure for two reasons, first, there is not enough pin protruding through the implement hole, and second, the pin is dragging on the ground and causing the pin to push back up through the hole.

The rectangle frame of the QA plate on the implement keeps the QA "feet" on the loader from moving down, and side to side. There has to be a gate way or door way for the foot to get inside the frame, and that occurs from the bottom. As you pull up to the implement, you place the top of the "foot" on the loader in the upper ^ part of the frame. As you lift, the bottom of the implement will contact the bottom of the foot. At this point, the pins are engaged, which is what keeps it from comming off. But, the load point is in the top (^) of the QA frame plate and the QA loader foot. As long as there is enough pin comming through to keep it from lifting off as you back up, you should be ok. All of the forward motion, digging motion will push at the bottom of the foot and the bracket. Thats why I don't think it makes much difference where the pin comes through or the hole location as long as you have enough pin protrusion.

I think we all agree that there are no issues pushing forward or lifting... or with lateral looseness. The potentially nasty issue (for me anyway) is back-dragging. I understand about pressure being applied to the QA's foot... but no matter how you slice it, those QA pins are in shear or even experiencing a bending moment to some degree depending on tightness of fit and exact bucket orientation. I guess I am just surprised that those pins are not beefier... and I'm wondering if they are beefier (wider? thicker?) on true skid-steer machines... but without seeing the industry spec for QA I am kind of left to wonder.

Dougster

 

[Dougster]

On mine the pins cannot pop back up if the egagement lever arms are all the way down. They force the pin to full extension and then overcenter slightly to a hard stop. A spring serves to detent each lever into the engaged/pin forced position. The only way the pin would push out of the slot would be to bend something unless the lever is for some reason not in the overcenter position.
larry

What about pin strength Larry? You're an engineer. Are you convinced that the pin size on your loader... if about 1" x 3/4" more or less like mine and like the ones shown above... is adequate in strength for the kinds of loads you can experience while doing some heavy-duty back-dragging?

Gotta admit it... I am a bit skeptical.

Dougster

 

[Dougster]

Hazmat, I resemble that remark (retiring at 56) but there was as much luck involved as anything else. That and because I was quite proactive in the fact that I wrote a detailed economic analysis that conclusively demonstrated that my job should be abolished. A side effect of my job being abolished, since I had over 20 years service, was eligibility for early retirement.
Pat

Funny coincidence! My brand new BOSSMAN wrote a detailed analysis that conclusively demonstrated that my job should be abolished! The difference was that early retirement in my industry means living off your meager savings and food stamps until age 62 when reduced benefit social security can finally kick in.

My big mistake was not entering the public sector... but too late now.

Dougster

 

[SPYDERLK]

What about pin strength Larry? You're an engineer. Are you convinced that the pin size on your loader... if about 1" x 3/4" more or less like mine and like the ones shown above... is adequate in strength for the kinds of loads you can experience while doing some heavy-duty back-dragging?

Gotta admit it... I am a bit skeptical.

Dougster

Yeah, they are plenty strong. Thats assuming they are always made from high strength steel. They are probably grade 8 equivalent, and are supported to within an inch of the point bending load is applied. Further, the implement tries to escape by pivoting off so the force vector on the pin is not at a rt angle where it would cause the maximum bending moment. Instead, it is aimed slightly upward - more nearly acting at a rt angle to the cut on the pin. The cut doesnt weaken the pin as much as one may think because the leverage increases as the distance from the applied load - just as the effective cross section of the pin does. Think about the force you can put on a big breaker bar. I believe 3/4 drive ones are about 7/8 diameter. Over a thousand ft-lb easy. Twelve thousand pounds of force at 1" from the pin support for each pin - and the pins are bigger. This is not wimpy.

I have back dragged with my 7520 with the fronts off the ground and the bucket near vertical. Sometimes the loaded rears were scrabbling. I have had no problem with the pins. I think the pins are actually more robust than the slots they engage on the bucket. Just so the tips of the pins extend at least 3/8" thru the slot I dont think you should worry - just use it.
larry

ps: Just ran out in the rain and checked. My pins are 1.250".

 

[Dougster]

Yeah, they are plenty strong. Thats assuming they are always made from high strength steel. They are probably grade 8 equivalent, and are supported to within an inch of the point bending load is applied. Further, the implement tries to escape by pivoting off so the force vector on the pin is not at a rt angle where it would cause the maximum bending moment. Instead, it is aimed slightly upward - more nearly acting at a rt angle to the cut on the pin. The cut doesnt weaken the pin as much as one may think because the leverage increases as the distance from the applied load - just as the effective cross section of the pin does. Think about the force you can put on a big breaker bar. I believe 3/4 drive ones are about 7/8 diameter. Over a thousand ft-lb easy. Twelve thousand pounds of force at 1" from the pin support for each pin - and the pins are bigger. This is not wimpy. I have back dragged with my 7520 with the fronts off the ground and the bucket near vertical. Sometimes the loaded rears were scrabbling. I have had no problem with the pins. I think the pins are actually more robust than the slots they engage on the bucket. Just so the tips of the pins extend at least 3/8" thru the slot I dont think you should worry - just use it.
larry
ps: Just ran out in the rain and checked. My pins are 1.250".

Hmmmm... you made me run back out and re-measure. It could be more like 1 inch by 1 inch square up on the shank away from the taper. Hard to measure due to four deeply beveled edges. Clearly your pins are beefier, but I'm not surprised given the ML275 loader's ratings. Still, it does make me wonder if having a spare set of pins in stock might not be a good idea. That's one way of assuring that the existing pins will never break!

Your points in regard to strength of materials and applied forces & moments are certainly valid. At the end of the day, the proof will be in the pudding. I guess I still fear that sloppy fit could eventually do me in with enough back-dragging. We'll just have to see how well that new HD bucket fits once I get it home and take it from there.

Dougster

 

[tomlj75]

Here I go again showing my lack of smarts, but can anyone explain to me the differences I am seeing in the lower rectangular mounting holes on various quick attach buckets and other such FEL attachments? I am seeing quick attach buckets with one small lower mounting hole on each side, two holes on each side (one small and one medium size), and some heavier buckets with two larger holes (one medium size and one very big). I am also seeing buckets with just one small hole on each side but in a different position that my loader mount accommodates. Mama Mia!

I always thought FEL "quick attach" was "quick attach"! Obviously I was wrong. I must assume from the size of the holes vs. attachment weight that this has something to do with different weight or strength ratings. Can anyone direct me to a website or document that explains the different lower mounting hole configurations that I am seeing on quick attach buckets and what they mean???

Dougster

the inner holes are for the case 1835 skidder and the outer ones are for the rest

 

[Dick]

on my 4740 the bucket and forks implements use the wider rectangular holes. Given all the discussion, methinks you are "overengineering" the problem.