Any body built a knuckleboom loader

[muddstopper]

I have been trying to figure out the amount of force I would have at the base of a boom 16ft long. What i think might be correct, but not 100%, sure so I am going to throw it out there as see what others have to say.

I am looking at this as the boom having a lever effect with the root boom cylinder being the fulcrum. With one end of the boom being fixed and the lift cylinder being 2ft from that fixed point, I should have a leverage effect of 8:1(16ft/2ft). Using a 3in bore cylinder at 3000psi should give me a lifting force of 10tons or 20,000lb, /8= 2500lbs of total lift capacity. The total lift weight would have to include the weight of the boom and grapple. This would be with the boom fully extended and at a horizonal position and weight loads would be greater as the dipper boom is pulled closer to the root boom, or as the root boom is raised or lowered from the horizonal position. Does this sound reasonable?? Actual lift capacity would change if the root cylinder was mounted closer or farther than the 2ft number I used as mounting of the root cylinder.

I think this is the way to figure the lift capacity of the boom and cylinders I need to get the lifting force I want. I just dont know how to figure out the actual stress that would be applied to the base of the boom at the swivel. I found that the loader in one of the links already posted, used a shaft of 3in dia, but was only rated for 800lbs with a 9.5ft boom. I found another boom that used a 4in shaft for the swivel, but had a 1200lb capacity with a 11.5ft reach. A 24in diax14ft southern red oak will weigh right at 2500, and I think this would be the heaviest possible load I might encounter. At actual loaded height the dipper boom would probably be at less than half extention so total swivel stress would be calculated at around 12ft of boom lenght. =15000load at swivel base. It seems the closer the load the less the stress at the base, which would coincide with some of the load charts I have found. Well now I am rambleing, Someone tell me if I'm on the right path.

 

[cbailey1956]

Understand exactly what you are trying to accomplish. Went out and looked at my grapple. It has about a 30 inch long hub. Boom and dipper will reach 20 feet. Six inch boom cylinder. Does not like to handle 24" dia by 16' white oak. I don't even try to lift at full extension. Best can do is pull them in about 10' and then lift them up. I have used my new processor one time last week. Built it on a 82 Chevy 350 rolling chassis with one 16' 10" beam on one side to support the log deck. Work in process but it did advance the logs good to cut 16" rounds. If I was going to use a grapple to load logs it would require a lot of beefing up compared to current status. To handle 2500 lb logs I would want stabilizers that reached out at least 5-6 feet from the frame rail to prevent tipping. My prentice G sitting on a double reinforced ford 700 frame rail with its heavy duty stabilizers has led me to drink once or twice with its tipsy feeling at full extension. Back to your boom I think any road tractor drive axle would be sturdy enough using its outer full floating bearing setup. You state boom length of 12 feet. Is this total including dipper?

 

[Roadbuilder6]

Have you considered a Anderson M90
Log loaders | Anderson Group | Agricultural, Biomass and Forestry Equipment

 

[muddstopper]

The M90 only has a lift capacity of 700lbs and a 9.5ft reach. Even the M160 is a little small. Either way, I cant afford one so its a moot point.

I looked at a truck axle today I think will work. A 40000lb axle should give me one spindle and hub capable of holding 20,000lb. I think I can increase that a bit by using a large dia solid shaft connected at the axle flange and supported at the bottom with a bushing. I dont anticipate picking 2500lbs at full boom extention, but should be able to pick it up at half extention. I have to do some more calculating before I start cutting and welding.

 

[muddstopper]

Understand exactly what you are trying to accomplish. Went out and looked at my grapple. It has about a 30 inch long hub. Boom and dipper will reach 20 feet. Six inch boom cylinder. Does not like to handle 24" dia by 16' white oak. I don't even try to lift at full extension. Best can do is pull them in about 10' and then lift them up. I have used my new processor one time last week. Built it on a 82 Chevy 350 rolling chassis with one 16' 10" beam on one side to support the log deck. Work in process but it did advance the logs good to cut 16" rounds. If I was going to use a grapple to load logs it would require a lot of beefing up compared to current status. To handle 2500 lb logs I would want stabilizers that reached out at least 5-6 feet from the frame rail to prevent tipping. My prentice G sitting on a double reinforced ford 700 frame rail with its heavy duty stabilizers has led me to drink once or twice with its tipsy feeling at full extension. Back to your boom I think any road tractor drive axle would be sturdy enough using its outer full floating bearing setup. You state boom length of 12 feet. Is this total including dipper?

Total boom length would be 16ft. With dipper half retracted, lifting forces would be measured at about 12ft. Root boom at 8ft, dipper boom at 8ft, total 16ft reach. 2500lbs at 16ft would be equal to 40,000 lbs at the swivel. With dipper half retracted, 20000lbs at the swivel. I think the only way i would be able to load a 2500lb log would be to drag it as close to the trailer as possible so as to keep the dipper boom as close to verticle as possible. While raising the root boom, should lower the stress on the swivel. I'm just guessing at all this, hoping someone can chime in with a little advice. At any rate, it is going to be hard to find a larger axle to use as my swivel. In reality, I would probably see very few 24inx 14ft redoak logs. Anything that big would most likely be a saw log. And if I do find something I cant lift, the 362 husky will lighten it up.

Since this thing is going to be mounted on the trailer tongue, its important that I keep it as light as possible. It will probably weigh in at 1500lbs, but when traveling, the boom would rest on the back of the trailer to help spread some of the weight. I am shooting for a total combined weight (processor and boom) of around 7000lbs. Thats not counting the trailer. Steel for building will be heavy, but my big weight monsters are hydraulic tank and engine. I am looking at a 190hp 6068 johndeere engine and that thing weights close to a ton by itself. 100gal of hydraulic oil is about 730lbs. add 1500lbs for the loader and I am already halfway to 7000lbs. I recon my f150 will pull it, LOL.

 

[Yooper75]

Muddstopper, we have one of these IMT 16000 Series II 42ft and 6 Prentice Telstik 3300 33ft loaders here at work the manuals for the IMT should give some insight on figuring out what you can lift with your boom. There are some pretty good illustrations in the IMT manuals showing how the turntables are made.

16000

http://www.imt.com/en-US/Component.Display.html?RefId=96b5fb54-4efb-44d1-b2bf-ac4c1c8b8cbf

http://www.imt.com/en-US/Component.Display.html?RefId=779aeaf9-1ee6-41d1-ae8d-726d7312b054

 

[mikefromnh]

Another idea... Instead of a grapple to load the deck, could you use a winch to pull the logs to an oversized log lift? Like what wood mizer has on some of their mills.

 

[muddstopper]

Yooper, I wish I could just find a good used imt crane, but those pictured are consideably larger than what I need. I think to build something similar to the imt with its turntable design would also be pretty costly. I did a little checking on one of those thrust bearings and it was well over $1000. Gearing would also be pretty expensive, altho I havnt actually checked on cost. I kind of gave up on that ideal after finding out what the bearings cost. I will say a double #100 68th sprocket is almost $700, and a double #60 68th sprocket is about half the #100. Going with a axle assembly isnt going to be cheap to build either, but I can source a big axle pretty cheap and it will come with the bearings. I think it would take a lot less machining to make work as well.

Mike, I thought about the winch, but it means dragging the logs thru the dirt and also would be much slower loading the logs. I do intend to add a winch, but it would only be used to drag up logs out of reach of the knuckle boom. I wont be taking this machine to the woods, and will just be pulling up beside a log pile.

 

[Yooper75]

Yooper, I wish I could just find a good used imt crane, but those pictured are consideably larger than what I need. I think to build something similar to the imt with its turntable design would also be pretty costly. I did a little checking on one of those thrust bearings and it was well over $1000. Gearing would also be pretty expensive, altho I havnt actually checked on cost. I kind of gave up on that ideal after finding out what the bearings cost. I will say a double #100 68th sprocket is almost $700, anAd a double #60 68th sprocket is about half the #100. Going with a axle assembly isnt going to be cheap to build either, but I can source a big axle pretty cheap and it will come with the bearings. I think it would take a lot less machining to make work as well.

I know they're not cheap to build much less fix the last boom truck bought was a 2001 with almost 300k on it and I paid just shy of $80,000. It was more for information than anything and I will say that if you find a boom cheap run away as fast as you can because they are pretty ragged out and probably getting to the point of being unsafe to operate.

 

[CDN Farm Boy]

Buddy of mine just showed me a pic of one he saw for sale locally. Old firetuck cab with crane and processor in tow. Hydraulic driven circular saw. $15,000 asking