B7100 FEL bucket size

[torch]

I'm working on designing (actually, adapting an existing design) a FEL for my B7100. Does a 5 cu ft. capacity bucket sound about right? The owner's manual indicates a limit of 500lbs capacity for a FEL.

The same manual indicates a 42" bucket width, but the tractor is wider than that. I'd like to go 48" or so. So long as the weight is within tolerance is there any reason to limit the width to 42"?

 

[procraftmike]

My tractor is up at the cottage, but I am pretty sure the bucket width is right around 48" or slightly over.

 

[Lil Foot]

Mine is 42", but DEEP compared to modern style buckets.

 

[torch]

Ok, comparing your bucket profile to the tire size, I'd estimate it to be around 18" tall. And that the flat bottom is around 13" wide before it rounds up into the back. So, at 42", your bucket is probably somewhere between 5 and 6 cu ft. capacity? In which case, I should be in the right ballpark for weight.

 

[Lil Foot]

That sounds right, but tractor is 150 miles from me right now, so I can't confirm your dimensions.

 

[torch]

So I think I've got the arm and bucket geometry worked out. Designed for 2"x16" cylinders. Having researched other design comments on this board and elsewhere, the bucket can sit 3" below the grade and is positioned within one front tire diameter of the front axle.

Initial lift angle is 10.2°, which should provide 946lbs of gross vertical force at 1700 psi, and with a 1.25" rod diameter, 576 lbs of gross curl force. My initial plan is to try tapping the existing hydraulic system via the block and to use a 10gph joystick style spool valve 4-way pair with float on the arms, regen on the bucket tip and power-beyond for the 3pt hitch.

Arms are 2" x 3-1/2" x 1/8" box tube, with suitable gussets and fish plates to be added at joints, etc. Bucket walls to be 1/8" plate with added plate at cutting edges and a heavy angle across the top for hooks. Mounted to the arms with a quick-attach system meeting SAE J2513 dimensions (ie: skid steer standard).

Not shown is bracing from the towers to the front of the tractor and bracing from the tower mount to the rear axle. I intend to hold off on finalizing those details until I have this roughed out and in place.

Are there any obvious problems or suggestions for improvements?

 

[torch]

I just wanted to bump this in case someone had any design insights (good or bad) before I start ordering metal.

 

[scdeerslayer]

My only observation is that there's not much dump angle. With mine, the bottom of the bucket is vertical (and maybe even a little beyond) at full dump. Most of the time I'm at full dump before all of the material comes out.

 

[Lil Foot]

That would be my only concern also. If material in the bucket was the least bit sticky, I think you might have trouble getting a full dump. Tried to find a pic of mine at full dump, but I don't have one- I'll get one when I can, but not sure when that will be.

 

[torch]

Thanks for the feedback guys. The total bucket movement has to be less than 180° (and almost 90° of that is eaten up by the arm travel). So any extra dump with the arms up must come from curl with the arms down. Where is the sweet spot? How much curl can you get out of your FEL with the arms down?

Hmmm. That all said, I wonder: Can the range of motion be increased through the use of some strategically placed levers?

 

[08quadram]

The loader arms on my Woods FEL attach to the bucket within an inch or so from the bottom of the bucket. Seems like that and slightly relocated dump cylinders could get more dump and possibly more overall height? But, I design buildings, not loaders.

Mike

 

[torch]

The loader arms on my Woods FEL attach to the bucket within an inch or so from the bottom of the bucket. Seems like that and slightly relocated dump cylinders could get more dump and possibly more overall height? But, I design buildings, not loaders.

Mike

I don't even design buildings. I just try to put them out.

I can readily see how to increase the dump angle, but at the cost of the curl. I don't see a way to get more than 180° of rotation. If the radius set by the distance between the bottom pivot and the cylinder mount is equal to or less than 1/2 of the cylinder stroke, then the rotation will be 180° and there will be little or no power to rotate the bucket at either extreme. The radius has to be longer than 1/2 of the cylinder stroke, making the rotation less than 180°.

As near as I can figure it, the arms rotate approximately 90° from bottom to top. Since the bucket is mounted to the arms, the 180° bucket rotation becomes 180-90° -- so less than 90°. If I set the bucket to be vertical when the arms are at maximum height, then the bucket can be curled up no more than horizontal at ground level.

So, either I have too much curl at ground level, or I'm missing something here. Possibly a little from column A and a little from column B...

 

[Dave_eng]

For about 30 years, I had a loader bucket style like the one you are planning. It was on a bigger 2wd tractor
The frustration was that the bucket would not curl back enough to carry a full bucket of loose material such as gravel close to the ground.
I always admired the bucket mounting first found on backhoes and now on tractors which involve an intermediate lever to increase bucket movement.
I always intended to modify mine to incorporate this feature but ill health brought this dream to an end. With the original style I liked being able to tilt the bucket vertical and grade using the cutting edge of the bucket. You could see what was happening and dislodge rocks.
After becoming too ill to be doing mechanical work, I bought a new M7040 with a loader included. Its bucket has the extra lever and will curl back like a trough when you need to carry material.
The one downside is the caution from Kubota not to push with the bucket tilted down. I guess the lever which increases the range of motion of the bucket also increases forces on the system which it cannot stand up to. You are to only push with the bucket parallel to the ground and then you cannot see as the bucket is in the way of seeing the front cutting edge.
Dave M7040

 

[torch]

So the amount of curl is important, as I kind of suspected.

Based on the input received thus far, here is the Mark III design for your critique. It's definitely more complicated, but has the added advantage of keeping the bucket angle constant as the arms are raised and lowered:

 

[scdeerslayer]

I found this pic showing the same loader as mine. Looks like your new design is the same concept.

 

[08quadram]

Question. For simplicity sake, why not go with a single dump cylinder? That is what My Woods, has. I have not problem with curl and break out force. My only issue with lifting capacity. Seems that it would be easier to fab, cheaper to build, and probably handle anything that the tractor can handle.

 

[torch]

That photo is quite helpful, providing a better sense of proportion. I think my links at the bucket were too long in comparison, possibly putting too much stress on things. I've shortened them up in my design to be more similar in proportion. I lose about 10° of dump angle at the top and about 10° of curl at the bottom.

Also, the bucket cylinders cannot fully extend. I have four 2" x 16" cylinders I was planning on using. I wonder if that's going to be a problem.

 

[torch]

Question. For simplicity sake, why not go with a single dump cylinder? That is what My Woods, has. I have not problem with curl and break out force. My only issue with lifting capacity. Seems that it would be easier to fab, cheaper to build, and probably handle anything that the tractor can handle.

Yes, Yes and a conditional Yes.

As far as power goes, I think a single cylinder would likely be adequate. However, there is some method to my madness. My plan is to replace the bucket in the winter with a front-mount blower, so I want to leave the centre, between the lift arms, as uncluttered as possible since that is where the PTO driveshaft and the chute will be.

 

[08quadram]

That makes perfect sense. So here is a crazy idea. How about mounting your dump cylinders just to the inside of the loader arms. Would require a cross member, but instead of just a single cylinder in the center, you would have one either side. This should allow you room for the blower drive.

 

[torch]

I will need a cross-member between the arms in any event. However, I'm not sure what the advantage would be to mounting the cylinders inside the arms as compared to over the arms. Mounting them inside the arms would likely require having the arms further apart (to clear the air intake and exhaust). That puts more leverage on the bottom of the posts and therefore the required support.

Whether the cylinders are above or beside the arms, the total bucket rotation is still limited to less than 180°. Maximum force is exerted against the load when the cylinder is perpendicular (ie: 90 °) to the load and falls off to nothing when parallel to the load. For example, at 90° and 1500 psi, a 2" cylinder with 1.25" rod can curl 2,872 lbs. but at 10° to the load that drops off to 500 lbs. Plus, if the travel was allowed to hit 0° or180°, there's a good chance the cylinder would jam when time came to reverse it! So realistically, I figure the maximum rotation in a simple bucket to cylinder setup should be limited to around 160° or even 140°. But I'd love to hear what the commercial designs such as yours actually achieve.

That second last design sketch I posted has about 200° of effective rotation (ie: actual bucket orientation after lift arm rotation). The last one has about 180° of effective rotation, yet should be capable of a minimum curl force of 772 lbs. (actually less, since there will be friction in the system. I just don't know how to calculate that!). Should be ample for a 500 lb load of dirt anyway.