Any body built a knuckleboom loader

[muddstopper]

I am looking for plans on building a knuckleboom loader. I am wanting something like a Farmi or Farma to mount on a trailer. I have found only 3 on Utube and nothing searching the net. I was going to convert a backhoe attachment to a loader, but it weighed 3000lbs and a fellow drove in the yard today wanting to buy it, so now its gone. Just looking for ideals.

 

[BKBoiss]

I have always wanted to build one as well but time and money just aren't on my side. I too thought about using an old hoe attachment but the weight and the fact that they are meant for digging down not lifting up high stopped me. I do have plans of maybe using the hydraulic components off an old one when I get around to finally building one. I also have thought of maybe using an axel and hub assembly off an old truck for the turn at the base if the boom.

 

[muddstopper]

I built a small one for my wood splitter using a truck front hub. For firewood, it worked alright, but then I got ambitious and decided I wanted to know just how much it would lift. I grabbed a 14in dia redoak about 12ft long and the hub gave way. I need a lift capacity of around 3000lbs to lift what I want to lift. A rear axle housing and hub might work. I need to keep it light as I want to mount it on the trailer tongue, but will also be using outriggers to stabilize it.

When I bought the backhoe attachment, I had planned on turning it upside down and modifying the dipper boom, removing the bucket cylinder and adding a grapple. Too make it work, i pretty much was going to have to competely rework it. The work necessary to convert the backhoe to a knuckle boom was as much or more work than just building from scratch. Good points of a backhoe attachment is you have the cylinders and control valving to make it work. I just couldnt see how I was going to overcome the weight factor.

I need ideals on building the swing and base.

 

[BKBoiss]

Was that with a hub off of a big truck? I haul loads up to 75000kg during the winter on a 7 axle. I figure doing all the math that works out to about 5300kg per axle stub. Like 11000lb for the Americans. I think. It in theory should be able to handle way more than that. For the swivel I thought about a really low geared high torque hydraulic motor or a cylinder and heavy cable or roller chain set up like the rotate on a snowblower chute.

 

[franklin2]

How are you going to control the base? Have you ever used one of those lifts you put in your pickup? If the truck is not on fairly level ground, it's a little scary trying to manually control a heavy load and get it into the truck. It wants to always go to the lowest point and stop. If you pick something like a engine up somewhere other than the lowest point, you can get hurt when it takes off.

A backhoe has two cylinders at the base and a somewhat limited side to side travel. Would that be enough for your purposes?

 

[jaotguy]

so 3000 lbs to lift at 6 feet out = 18000lbs of torque at the base of the boom swivel ... ( at 7 ft = 21000 lbs )

that's some load at the base to account for .... like having 10 tons on one tire at the axle ....

perhaps you should look at an old boom truck for the base ( auction at a tree trimming yard or crane place ) ... one that is bagged out ( bad motor/trans / etc )

 

[BHD]

Log Trailers | Log Handling, Power | Husqvarna Chainsaws, Outdoor Power Equipment and Tree Care Supplies from Baileysonline

 

[mikefromnh]

The slew gear from a small mechanics crane off a service truck would be a nice starting point.

 

[BHD]

for the base, use some kind of pivot big spindle or pipe on pipe, and use a large sprocket and a roller chain with hydraulic cylinders, to pull it one could get a little more than 360 degrees. or a cable.

or a roller chain on a pivot point, driven by a hydraulic motor,

a hydraulic motor ad a large differential or gear box,

or a roller chain on a pivot point, driven by a hydraulic motor,

 

[BHD]

Log Boom Construction

 

[muddstopper]

BHD, that is what I am looking for. I need some info as to the gearing of the swing, I'll have to do a little math Ouch!. but all those pictures really helps.

I had the ideal of using the backhoe for the swing. everything was there, I just needed to lighten the load. I like the design of the log loader trailers, but not the price tag. Building something similar to the log loader trailers is what I have in mind. The knuckle boom will be mounted on trailer, but it will be part of a firewood processor and used to load logs onto the processor. I have looked for Mechanic cranes, but just not any around here, or at least not anything I can rob parts off of.

The hub I broke on my small boom was actually off a jeep cherokee front hub. It would have probably lasted for years just lifting a short round, but the stress of a large log on the end of a 14ft boom was just to much for the bearings and it pulled them out of the hub.

 

[mikehaugen]

You need to somehow use 2 thrust bearing spaced apart. A single hub has 2 bearings just a couple inches apart so the torque is multiplied much faster. If you built a column maybe 2' tall with tapered bearings on each end it would handle at least 6 times the torque (24" vs 4" spacing on the bearings). It's definitely do-able but will require some machine work more than likely. I had thought of this as well, and the pivot is definitely the highest hurdle in the project.

I would get like a 2-1/2" to 3" shaft and put a shoulder of some kind on it to rest on the top bearing, have the other end threaded to to preload the bottom bearing. Make a plate that fits nice and tight inside of whatever mast material you are using and, weld it to the end of the shaft that will go into the mast about a foot, then have another plate to weld to the bottom of the mast and to the shaft.

Sorry if this isn't clear, I am bad at explaining things but I can picture it in my head.

I also like the sprocket/chain idea. Get a large (like 12") sprocket and cut out square or round hole to fit on whatever mast you are using and drive with hydraulic motor. I would even consider mounting it below the pivot hub, though it doesn't matter much either way.

 

[muddstopper]

I have some shaft, about 3in dia I think. I remember dads old bigstick wood loader. The boom just swiveled on a solid shaft with a hole thru the middle. The hole was for the cable to run thru. I am not sure of the solid shaft size, but know it was probably 3in or larger. The boom turned by use of 2 hydraulic cylinders. There was a drum on the bottom of the boom which cable was wrapped around. The cyl would pull the cable and make the boom turn. We loaded some big logs with that loader. whitepines 4ft+ in dia and usually 12ft long. We also broke several of the turn cables. Later dad sold the bigstick and bought a kenimer loader. Boom mount was basicly the same, but the boom rotated with the use of a sprocket and chain. Broke a lot of #100 chains to. As I recall, neither of the loaders liked to rotate with a heavy load. I suspect that if i go the hydraulic motor and sprocket, I would probably look to do something similar as show in the link BHD provided. A double sprocket, and best i can count, looks to be 60 teeth on the bigger sprocket. Biggest sprocket on the surplus center site is 60tooth, #60 chain and only a single sprocket at that. Looking at the picture in the link, it appears to have two single sprockets spaced to accept a double chain, not a true double row sprocket. After looking at the pics, I think I have a plan to make the swivel. Got to check out some spare parts to see if what I have in mind will actually work so i wont comment on my plan. Maybe i will anyways. Someone might save me the trouble of trying what I am thinking

I think I can find a big truck rear axle. Cut the hubs off each side, but leave the axle tube long for trimming later. Weld the axle tubes together and run a big shaft thru the middle to connect the two hubs. I can use the flanges off the axles to weld to my large shaft. Connect my sprocket to the bottom hub and make the turning part down low. I can use the axle tube to weld in the frame and the hubs should turn freely. Mount knuckle boom to top hub. This should provide me with a top and bottom bearing support (4 bearings). Just dont know if I can make a sturdy enough mount to weld to the top hub that will hold the boom. I'll just have to go look at a truck axle before I am satisfied it might work.

 

[cbailey1956]

Interesting, I have been thinking that a large truck rear differential (17000lb cap) would be a good start. What I am thinking is to cut off one axle tube and weld a plate to hold the lube in. I want to place it axle up and use a rim to support the boom. I am thinking a hydraulic motor could be used to drive the differential like a driveshaft but might have to use chain and sprocket to adjust speed. Have to play with spider gears to lock differential but seems doable. I have an old prentice g that the head is all cracked on and would like to lower it and make a boom trailer out of.

 

[muddstopper]

A 17000lb axle might do and is sort of what I have in mind. Actually, I am thinking road tractor rears. I dont think using just one hub will carry the weight of the boom and load fully extended. A 17000lb axle is only rated for 8500lbs per side. I dont know the math for figureing out the total leverage weight of a 3000lb log at the end of a 16ft boom. A lot of leverage on a couple of bearing spaced less than a ft apart. That is the reason i am considering using both hubs, one at each end of the support tower. I think if i cut the cap off the axle shaft and replace the axle with a large piece of solid shaft, and then figure out a way to attach the round shaft to the other axle/hub cap, I would have the support of the 4 hub bearings, two at top and two at the bottom of tower with the added rigidity of the solid shaft material running thru the support tower. Maybe overkill and might not work as I think it would.

 

[mikefromnh]

There are a ton of atv log loaders on alibaba. They almost all look to use the same base design of a rotary actuator and some sort of slew/ring bearing. They must have a cheap source...

 

[mikefromnh]

This looks like what mike h was describing. It's the wallenstein timber talon 95. They use a "fiber glide thrust bearing" between the inner rod and outer pipe.
http://www.embmfg.com/File.aspx?id=2fcf52b7-77fe-416b-bcdc-7d9ec50ca357&display=full

 

[muddstopper]

Thanks Mike, I see that the support shaft on that loader is 3in dia. Looking at the specs for the loader, it is only rated for 900lbs. Not big enough for what I need, but the drawings can be adapted and scaled up.

 

[Baby Grand]

Do you plan on adding stabilizers?
I used to run 2 trucks with Prentice G & H model booms, like cbailey1956 mentioned, and those stabilizers saved my butt more than once.
Used to put a 2 foot 2x12 under each of the pads when the spring thaw softened everything up, or after a week of rain.

 

[muddstopper]

I think stabilizers would be a must have for a loader. Since i plan on mounting it on a trailered wood processor, I am considering stabilizers on each corner. My plans are to drive up to a pile of logs, use the loader to load the livedeck, and use a conveyor to carry away the splits. I have been gathering parts for a few years now and am about ready to start the actual build. Plans constantly changing as i find materials, I upsized the original plans a few times already, but now I think I have a final vision in mind and only time and money are standing in the way.