Any body built a knuckleboom loader

muddstopper · Oct 22, 2014

CDN Farm Boy said:
As I read along with this, something just isn't sitting right to me...that something is missing in the calculations. I figured out what it is this morning.

You say you are looking to pick up 3000 lbs at the end of the 16' boom. My math tells me that will equate to 48,000 lbs of leverage at the pivot. Never mind the specific design of the pivot, I don't think you'll have enough counter weight in your 7000 lbs trailer to do it. Yes, outriggers will shorten the lever length but have you checked on this part of the math?

You are almost correct. The 3000lb number was with boom retracted, not at full extention. With dipper boom at a 90# angle to the root boom, loads would be aboth half of what they would be with both boom fully extended. I dont antisipate ever haveing a 3000lb log hanging from the end of a fully extened boom. I can see a possibility of reaching and dragging a 3000lb log close to the trailer before picking it up I also intend to use outriggers at all four corners to support the trailer. The 7000lb weight number is the estimated weight of the loader and the firewood processor and doesnot include the eintire weight of the trailer. Trailer is 8ft wide and close to the ground, I havent figured out a lenght for the outriggers, but if measured from the center of the loader to the outermost point of each outrigger, i would have to guess the outriggers would be 16ft wide tip to tip. I havent actually drew anything up to take measurements from. I do see your point of overbalanceing the center mast and think this is certainly something that needs to be considered. I do think the math would be the same as figureing leveage force of a lever, with the outrigger being the balanceing point and the boom being the lever. With a fulcrum of 8f from the center of the mast, with a levr of 16ft, it should be a 2:1 weight ratio. If extended lenght of boom is 16ft, and oputriggers are at 8ft from mast, the opposite 4ft of the trailer width would be my counter weight. If trailer weight is 7000lb, than counterweight potential would be 3500lbs. Since the boom would be mounted on the end of the trailer, I would probably have to reduce the counter balnce by anothe 50%. Of course these numbers are just off the top of my head and probably wont reflect the actual trailer weight or counter balance effect. This is something i have thought about, but just havent figured out if my method of calculations are correct. Any ideals as to whether I am on the right track will be appreciated.

mikefromnh · Oct 22, 2014

If it starts to tip just lower the boom

Yooper75 · Oct 22, 2014

Muddstopper, I don't know if you've ever run a boom like you're trying to build but they are a different animal and I've been running them for going on 14 years. I think you're 3000# retracted is overly optimistic since the biggest loader we have can do 3000# at 42ft of stick fully extended and about 4,700 retracted mounted on a truck that weighs just under 36,000# empty with the loader. The biggest Wallentein logging trailer with boom will do 1200# at 11ft of reach full stick which is half the reach of our biggest IMT retracted the biggest thing you're going to have to worry about is getting something very heavy at the end of the stick and the hydraulics being stronger than the material ripping the boom apart trying to overcome the weight of the boom/load. Our IMT and Prentice loaders have pressure relieves built in so they don't rip themselves apart and will actually stop working if you reach the working limits of the loader with the only function is to lower/knuckle in the boom until you get back to safe operating limits. There is nothing more nerve wracking than having a 3,600 pound unit of OSB hanging off the stick over someones new floor and the loader says nope you're done when you reach the load limits or the truck/loader start to go over if an outrigger lets go or the ground collapses under it with you sitting 13ft in the air with no where to go.

Baby Grand · Oct 22, 2014

Most excitement I can remember was with the Prentice, trying to put a 30 sheet unit of 12' 1/2" sheetrock through the second story window opening in a just sheathed house. Boom was fully extended at right angles to the truck. Stabilizer started to settle into the ground causing the whole shebang to tip in the load direction. Hydraulics barely recovered the load because even at a slight tip angle it didn't have enough mustard to spin the load. Only by bringing the load back, closer to the mast could I keep the boom turning the right way and the vehicle from going over into the excavation around the foundation. Sitting on top of the mast just adds to the excitement!

Yooper75 · Oct 22, 2014

My favorite was trying to stick a unit of 5/8-4x16 sheetrock through a window with a 20mph North wind trying to rotate either the entire loader or the forks every time I eased off on the hydraulics for those two functions. The next I was running our new IMT 42ft boom nosed up to the house with the stick fully extended 48+ feet in the air to unload a pallet of shingles on a 3 story home and the roofer decides to stick his feet in the pallet and tosses 80# bundles to the guys on the roof while swinging is the breeze with no life line.

Good times!!:laughing:

muddstopper · Oct 22, 2014

You havent ran a loader until you run one with rail wheels. Then have it derail in the direction of a passing train. Yea, I can come up with some scary stories too. Non the less, I do understand the limitations and have several years of experience running one. Just not lately. Once ran a tower crain dropping materials down a shaft . Bottom of tower was 90ft in the air, Seems like the boom was 90ft long with a jib attached to the end. Bossman told me I needed to grease the roller at the end of the jib. Handed me a flashlight, (I was working night shift), and a grease gun. He expected me to crawl thru the framework to get to the jib. I turned in my 5 days notice then and there. Far as I know, that roller has never been greased.

My intentions are to run this boom from the ground. I am not a big fan of heights, just in case my last story didnt give that fact away. Anyways, I can concur with the statement about having more lift capacity than the boom can handle. I dont think that will be the case here, but is something that needs to be well thought out before buying the steel for the boom. Glad for the reminder because even though I know this could happen, I havent been thinking about it.

I have looked at the Wallentien loaders, and the Anderson, and the Farmi and just about every other brand out there. I think that 1200lb rating is with the boom fully extended at 11ft. One of the manufacturers, I dont remember which one, uses a 4in solid shaft as the swivel support, another uses a 3in solid shaft. Both use 2 1/2 in bore cylinders. I plan on the 3in cylinders and a bigger spindle support. Also those small knuckle booms are mounted on narrow trailers. My trailer will be 8ft wide. They use one outrigger on each side (2), I plan on using one at each corner (4)That factor alone should give me more insurance from tipping. I havent planned on the lenght of the outriggers yet, but that is also another factor in lift capacity. Really my biggest concern is over powering the spindle and, now that it has been brought up, ripping off one of the booms. I think one can limit the lift capacity by using pressure reliefs in the hydraulics. I know there is probably some equasion that says you can only lift this much if you do this thing, but I dont know it and will probably have to use trial and error. In reality, I am planning on lifting firewood logs, if I run across a 3000lb log, it will probably be set aside and sold as a saw log. A 3000lb log is about a half a cord of firewood, maybe a little more once split and measured in cubic ft instead of weight.