Kubota Skid Steer QA Question?

   / Kubota Skid Steer QA Question?
  • Thread Starter
#11  
Thanks Folks

I took my tractor and grapple to a neighbor that has a nice welding shop. After much looking and discussion we welded a piece of 3/8 plate about 1 1/2"
square on the latch plate as Walt's pictures show. This solved the problem. The grapple seems to be solidly attached now. I don't think it could come loose now even with some serious backdragging. If it doesn't rain I will find out tomorrow. I have about 3 acres of white pine sapplings that need attention.

Thanks for your help and advice!
 
   / Kubota Skid Steer QA Question? #12  
My Kubota L4330 with 853 loader had the same problem when I mounted a Bush Hog rotary mower on the FEL driven by a hydraulic motor coupled to a PTO hydraulic pump. I made the QA brackets, and I did as Walt did and added a 1/2" thick block to the lower plate so that practically the full tapered surface of the pins was against metal. Because the Bush Hog sticks out quite a bit forward of the FEL attachment point, the twisting force on the QA when the front edge of the mower travels over a log or high spot must be substantial. And this force is trying the pull the bottom of the implement bracket away from the bottom of the bracket on the FEL where the pins are located. One or both pins popped out several times.

I think the problem is the roughly 45 degree angle on the pins combined with the grease zerks on the pin bushings. On dry metal a 45 degree angle may be barely sufficient to avoid having the surfaces slide on each other from a squeezing force, but when the surfaces are lubricated the angle should not exceed around 10 degrees (depending on the exact type of metal, lubrication, etc.). Over time oil leaks out of the grease on the pin bushing and creeps down onto the tapered surface of the pin. Thus the tapered surfaces of the pin and the stop blocks on the bracket become lubricated to some extent and the 45 degree angle on the pin far exceeds the 10 degree angle of repose necessary to avoid upward force on the pin when backdragging or otherwise twisting the attachment away from the bottom of the QA. If the upward force is not too great the springs may not compress enough to allow the pins to slip out. But in my case the springs compressed roughly the 1 inch necessary for the pin to slip completely out.

Note that the angle on most door bolts is about 45 degrees, and those bolts are easily pushed into the latch when a door is closed.

I think I solved the problem by putting 1 1/8" long bushings inside the springs around the central 12mm bolt. These bushings are short enough to allow the locking handle to pass through center when inserting the pin into the implement, but they are long enough to keep the pin from moving up more than about 1/4" when the handles are locked.

The bushings I used were from McMaster Carr, part # 6391K201. They are SAE 841 bronze sleeve bearings for 1/2" shaft diameter, 11/16" OD, 1-1/8" length, and cost $1.59 each. I guessed at the length and OD. I think there is probably room for 3/4" OD for a little more strength and length of 1-1/4", but these work fine so far. If I were doing it over again I would probably use 3/4" OD tube with 1/8" wall thickness for greater strength, but I suspect the bushings will be more than adequate.

The bushings are installed by removing the single 12mm lock nut on the bolt that runs from the pin through the spring and then into the swivel block on the handle. Takes about 5 minutes.
 
   / Kubota Skid Steer QA Question?
  • Thread Starter
#13  
Farmerford

I think your fix with the bushings is a great idea. Where did you find the bushings?

Update:
Should have looked before I asked. Google found the McMaster Carr site. Looks like they have a good selection of just about anything you need. Do they sell to the public or just dealers?
 
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   / Kubota Skid Steer QA Question? #14  
North Ga:

McMaster Carr will let anyone open an account on line with a credit card. I have bought from them for years. Small orders are not a problem. If you are in the Atlanta "one day" delivery area, you can e-mail an order late one day and get it late the next day. I am in Columbus, Georgia and routinely place orders on Thursday afternoon so I will get them Friday for the weekend.

I think McMaster Carr's catalog (print and on line) has much more technical information than Graingers'. And with one day service it is quicker to order from MMC on line than to drive across town to Graingers, where it will not be in stock anyway. MMC's shipping charges are very low.

However, for cutting tools (drill bits, taps, etc.) I think KBC Tools & Machinery, that I learned about here on TBN, has a better selection and often a better price.
 
   / Kubota Skid Steer QA Question? #15  
I have a Piranha grapple and stump bucket and have the same gap problem with the quick tach. All my other quick tach items fit fine, that includes New Holland's largest skid steer light material bucket, Kubota heavy duty bucket, bale spear and pallet forks.

I welded a 3/4" shim on the Piranha items and that fixed the problem. I think they build them with loose tolerences, I know they have a great price though!

I also did the spacer inside the pin so it wouldn't slid in a far.

ksmmoto
 

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   / Kubota Skid Steer QA Question? #16  
Farmerford said:
My Kubota L4330 with 853 loader.... Bush Hog rotary mower on the FEL driven by a hydraulic motor coupled to a PTO hydraulic pump.


Farmerford,

I wish you would take a picture of that setup and start another thread discussing how you like it, why you used a PTO instead of the internal hydraulics, and anything else.

Thanks,

John
 
   / Kubota Skid Steer QA Question?
  • Thread Starter
#17  
Ksmmoto

Thanks for the pictures. Maybe Kubota should hire you and Farmerford to design their attachments!

I talked to my dealer about my problems yesterday. The head mechanic had just returned from a Kubota repair seminar about two weeks ago. They discussed the skid steer qa problem in the seminar so the mechanic talked to the technical folks at Kubota. The plant is only about 30 miles from the dealership. Kubota is sending another qa unit for my loader and they will come and change out my qa unit. He asked that I hold up on any more welding of spacers until they changed out the qa unit. My unit has black wedge pins and the updated unit has the plated ( gold/chrome) wedge pins that are also longer than the black pins. I don't think Kubota would readily agree to change out the unit unless they knew they had problems.

I will post the results of the updated qa as soon as the unit has been changed.

I also received a UPS package from Piranha yesterday. It contained about 50 lbs. of latch plates. I really feel bad about complaining to them about the fit of their equipment because it looks like a Kubota problem now. We will see.
 
   / Kubota Skid Steer QA Question? #18  
I make my own QA plates and I use 45 degrees for the top and 30 degrees for the bottom with a 1 inch hole at the bottom and my Case 1845 C is different that a tractor, I am using the same type of skid steer QA plate. I wish I had another machine to try and make sure they will interchange
Jim:)
 
   / Kubota Skid Steer QA Question? #19  
NorthGA:

Please keep us posted on the replacement QA. Sounds like I should have complained to my dealer, and I may do so yet after I learn how it goes with you.

jmc:

I mounted a Bush Hog 48" squealer on a Kubota B2400 FEL first and then upgraded to a Kubota L4330 when the B2400 proved too small to fully utilize the mower. The hydraulic motor is a Char-Lynn 4.9 cu in/rev that turns about 600 rpm @ 11gpm flow. It connects directly to the input shaft on the Bush Hog gear box with a chain coupling. I built a platform for the motor right in front of the gearbox and used shims under the motor mount feet to line up the motor and gearbox shafts with a dial indicator.

The pump is a Prince 5.7 cu in/rev unit that puts out 11.2 gpm at 540 pto rpm (about 18 hp before losses). I built a three point hitch platform that holds a 15 gallon baffeled reservoir, return line filter, relief valve, and the Prnce pump. I mounted the pump on the tph platform and drive it with a short driveshaft from the pto to make it easier to hook and unhook than if it hung directly on the pto shaft.

The Bush Hog points toward the front (ie, open end in the direction of cut, just like on the tph) and I replaced the single caster tailwheel with two fixed wheels, one on each side at the rear of the mower.

I use it for clearing heavy brush on about 80 acres of Georgia rolling land. It is most effective on pines up to about 3" dia and hardwood to about 2". I raise the mower up to about 5' off the ground, angled with the curl on the FEL so that the tractor is masked from the blade by the housing, and lower it slowly into the brush. To control the lowering speed I installed a Prince pressure compensated flow control in the FEL lower circuit (base end of the lift cylinders) which is controlled by an additional handle on the FEL control station. If the trees are typical (say 2" pines), I let it drop fairly slowly. If they are 1" and smaller it can drop pretty fast.

I also converted my FEL joystick to a two handle system because, in this particular application, it is easier to control when the raise/lower and curl/dump are on truly separate handles. The flow control in the curl circuit makes it a three handle system that sounds awkward, but it makes the mower much easier to use.

I added two carbide tipped stump grinder teeth to the undersides of each of the two standard Bush Hog blades, one at the very end and another a few inches in. The teeth barely brush the ground when the Bush Hog is resting on the skids/wheels. The stump grinder teeth cut the stumps off clean at ground level, so the surface is absolutely smooth when I am finished. The stump grinder teeth also help break the tree trunks and branches up into very small pieces. Although it is slow, when I finish a spot it is very clean: no limbs, leaves, or stumps. Everything has been turned into wood chips and scattered. That way we can start mowing with a mid-mount mower on the B2400 and keep it clean thereafter.

I ususally mount my Vermeer PTO chipper on another tractor and keep it close by. Trees larger than the Bush Hog can comfortably handle are cut down and chipped. And the stumps on even the larger trees can be cut to ground level with the chipper teeth on the Bush Hog.

So, when we finish the ground is clean and level, free of stumps, with just the litter of chips, leaves, etc. It is not as slow as I may have indicated, but it certainly is a far cry from charging through the woods with the Bush Hog out front at the same speed you would mow the pasture. In the same vein, it is also a far cry from cutting that stuff down with a Husqvarna brush cutter, pulling it out of the briars and vines, and hauling it to a chipper or burning it. And, although there are a few fist sized pieces of wood flying through the air once in a while, I am convinced that I am more likely to cut off a foot with the Husky brush cutter than I am to get brain damage from a wood splinter.
 
   / Kubota Skid Steer QA Question? #20  
jmc

I am over my head on this attachment business. There may be a photo of the pump setup attached. If there is I will try to send some more along. If there is nothing attached, I will have to wait for my daughter who understands how to do it.
 

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