Home brew boom pole

[patrick_g]

I put this together when I welded up the bucket forks....You'd need a big tractor though....this one weighs in at about 10K lbs....bobg in va

Bob, Yours is more like what I want. I won't need the BIG tractor as I will not be going after as heavy loads as you. You get more strength for the weight of materials used with a design along the lines of yours. I just need to lift lumber to build a barn and such. Nothing two guys couldn't pick up (<= 500lbs) but a second guy isn't often available. Without proper triangulation the pole would have to be really heavy to not get bent. A properly engineered light weight pole along the lines of yours will not be too much to wrestle with getting on and off.

Pat

 

[pat32rf]

Citifarma- When designing something always look at the direction that the force will be applied. If your crossbar was below your hitch-pins you would have been trying to stretch the steel, instead of twisting it. You would still have to gusset it but you would only be trying to bend the steel in one direction while lifting. Steel is hard to stretch but easy to bend. If you put a coupla thin steel rods forming a triangle above a boom pole it gets a lot stronger. If you try to put them under the pole, they will just bend. Always try to design so you are pulling on steel, not pushing or twisting unless you have a large cross-section.

 

[patrick_g]

Citifarma, Said another way, steel has high tensile strength. Try to put stressed parts in tension not compression. Design triangulation and bracing so that "in theory" you could use a chain or rope. You can't push a rope. Design your braces to be pulled on not compressed.

Pat

 

[JC-jetro]

Citifaram,

And again....... in another word, put the part in compression and take the load off of the joints. Look at the sort of gusset plate and the way I put pieces to together. almost every thing is in compression and even in the lower link I avoided the shearing force by using and angle piece rather than welding the pipe to a flat stock.

 

[RonMar]

And a single shank ripper is great for removing bushes and brush. You dig in on the far side, the shank tangles with the roots and when it gets in to the rootwad/stump, you lift the 3PH and out they come, roots and all. You don't have to get off the tractor to hook up a chain or anything.

By extending your 3PH lifting force out onto the end of a boom pole, you have greatly reduced you available lifting force(sacrificed pounds lifted for greater movement of the boom). If you are pulling forward with it, the pull force will be applied to the tractor way up high at the toplink attach point well above the axle. I am not a big fan of tractor wheelies I guess. The boom length will also amplify any down force and attempt to lift the front of the tractor off the ground. Just like Archemedes said, give me a fulcrum and a big enough lever and I will move the world...

Weights out on lever arms can be tricky, just ask a crane operator. I suppose a proper boom pole on a FEL could be usefull, but it could also be a good way to collapse the FEL structure, pretzel the FEL lift cylinders or stand a tractor on it's nose or side. And heaven forbid, the structure fails at the base pivot pins for the lift arms as this might send the structure back towards the drivers seat. Lifting pieces for a roof into place would be easier as the boom angle rises more toward vertical, the stresses become less. But lifting pieces down from the roof could be a real surprise. You may get the thing off the roof but as the FEL/boom come down, if the weight is too great, the ammount of applied leverage out on the boom could exceed the FEL structural limits, or topple the tractor. Modern cranes have safety devices that will halt the crane movement if weight and angle limits are exceeded(but they still manage to tip them over from time to time.

And if the hydraulics can get the FEL/boom with load off the ground in he first place without opening the safety, you must be within limits, right? The problem will most likley arise when you start to move the tractor to position the suspended load. Force = Mass X Acceleration. This is a fact and there is no way of getting around this. You may have enough power to lift the 100# truss or beam on the end of the boom and be just within limits of the loader structure and hydraulics, but now you need to position it. What do you think is going to happen when your no suspension tractor rolls over an obstacle or hole or you accelerate or decelerate too quickly. The boom is going to move and since it is out there a ways on that long moment arm, it is going to move a lot. When it comes to the end of it's movement, that load is going to decelerate and pull some "G"s. When it does, you are going to have a whole lot more load applied to the structure and hydraulics than you lifted off the ground while setting still.

My .02

 

[JC-jetro]

My .02

That 2 cent was worth a bucket of gold. Well said Common sense should always prevail over the limit of any mechanical contraption.

 

[patrick_g]

While I have no quarrel with Ron as his analysis and conjecture is in fair agreement with mine, I do think I would mention that there is a missing structure on the pictured pole.

The HD supports connected to the mid point of the pole give the pole a nice place to fold when stressed in pulling at some brush. What is needed is a spreader sticking up from the pole with a TENSION member running over it out to near the tip or to the tip of the pole (like guying a sailboat mast.) This will stiffen the pole greatly at little cost in weight of materials or, cost/effort of construction but will increase the lifting capacity before bending the pole by a huge factor. For the same strength, the weight of the pole can be much less using the spreader and tension member. Lighter is better for the guy putting the implement on and off the tractor and lighter leaves more tractor capacity for doing work and not holding up the heavy pole.

In my particular (anticipated) use of a pole, I will be lifting things within the "horizontal" lift capacity of the tractor and do not anticipate driving around with an elevated load, maybe just some very minor positioning as I have a great respect for the physics of the situation and have no desire for a Darwin award.

As far as pulling brush... A toothier version of the tooth bar on the front of the FEL bucket is a good tool. The longer teeth with gentle taper alow yoi to wedge the brush trunks firmly between the teeth. Do this with the bucket parallel to and just skimming the ground. Then use curl to rotate the teeth up. This doesn't try to lift the rear wheels off the ground. It acts like pulling a nail with a pry bar or claw hammer. In use, either of those tools rests on the work piece and generates good leverage. Similarly you generate good leverage with the rotation of the FEL bucket while keeping the "heel" of the bucket in contact with the ground to act as a fulcrum.

After you pull the brush out of the ground yo can return the bucket to horizontal and press it to the ground and then back up a bit to "unfork" the brush and clear it from the teeth. This can also be applied to remove smaller brush from a fenceline if it is not too entangled with the fence wire.

Pat

 

[JC-jetro]

The HD supports connected to the mid point of the pole give the pole a nice place to fold when stressed in pulling at some brush. What is needed is a spreader sticking up from the pole with a TENSION member running over it out to near the tip or to the tip of the pole (like guying a sailboat mast.) This will stiffen the pole greatly at little cost in weight of materials or, cost/effort of construction but will increase the lifting capacity before bending the pole by a huge factor. Pat

Well said, That's why I had to re-visited my design after a bit of R/D.I used a piece of strut welded to the top and a tension piece as well. I can clearly go to the limit of my 3 point lift capacity and the improved design does not show any sign of stress. I reckon great minds think the same

 

[patrick_g]

Well said, That's why I had to re-visited my design after a bit of R/D.I used a piece of strut welded to the top and a tension piece as well. I can clearly go to the limit of my 3 point lift capacity and the improved design does not show any sign of stress. I reckon great minds think the same

The pessimist thinks the glass is half empty. The optimist thinks it is half full. Engineers, scientists, and economists think the container is twice as big as it needs to be wasting material and money.

Properly guyed, braced by spreaders and tension members (guy wires), a rather small diameter light weight boom pole is of sufficient strength to take anything a moderate tractor can put out. Total weight can be significantly less but strength and lift papacity more than the HD pole approach.

The trick is to keep the pole in compression and "IN COLUMN." If you allow the pole to bend then it will rapidly destruct under max forces.

Pat

 

[jsborn]

The pessimist thinks the glass is half empty. The optimist thinks it is half full. Engineers, scientists, and economists think the container is twice as big as it needs to be wasting material and money.
Pat

You forgot the Safety man who wants it to be 5 times as strong and can only be used by licenced /trained and certified personal under direct supervision of 3 inspectors.

Just had to through this in sorry.