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Whatever I decide to build in the way of a loader, it has to be simple, and I have an articulating arm in mind. It uses no track or fancy winch like the Kelly and other boom loaders. I have limited needs and my boom only has to have a radius of a few feet -- 10 or 12 feet maximum, and has to mount on either a pickup, a trailer, or the forklift -- or possibly interchange between all of the above using a common mount. I only need about an 8-foot swing, but will probably over-build so that I don't find myself too constricted.
Longer booms are harder to swing to the moment of inertia which increases with the square of the boom length. (I=mL2/3). Articulated booms get around this somewhat since each section is half the length of an equivalent straight boom and each piece moves independently and has its own moment when working close to centre. Nonetheless, the rotating effort increases with longer booms.
A second problem is that any long boom has too much leverage when the load is far from the main pivot and will tip a light vehicle to the extent that the load will swing out and run downhill away from the centre with increasing force, and at some point become unmanageable unless the boom is re-leveled to compensate.
At that point, the operator is struggling to maintain control with both hands and can't let go until it reaches the maximum possible distance, at which point the load cannot go further and again is manageable. but we can see that too long a boom could seriously tip a light vehicle unless equipped with stabilizing legs out to the side.
I can an put a limiter on the elbow joint of an articulated boom so that it cannot extend past the point where it runs away on me if that becomes a problem, or simply make a shorter end boom that can be exchanged for the original for some situations.
The other solution to the tipping problem and consequent loss of control when moving away from the main pivot, one which is used on the Billet Ezyloader, is a re-leveling setup which can be automatic or manually activated by the operator from the remote controls. Here are some potential actuators: One Two Three.
Two mercury switches (and solenoids if required), mounted such that each turns on only when the mast is off-level one way or the other, can be wired in series with each of two such jacks mounted at right angles to one another at the bottom of a hinged main post. For stable vehicles operating on level ground, only one such jack, for side to side tipping compensation, is often enough. The degree of vehicle tipping front to back is normally very small in comparison to the amount of tipping side to side and much less troublesome.
My design will require 12-volt power and probably use a cheap 12-volt winch for the lifting. The winch will mount at the outer boom tip since it is easier to run a single high current 12V line out the boom than to run both the control cable and the winch cable. The 12-volt return (negative line) can be the boom frame itself, and the vehicle frame so that only the one heavy wire needs to run out the boom. Ground jumpers might be required at the pivots, but normally the ground current seems to travel through steel hinges just fine without them.
The alternative is to use a 110-volt winch which is quieter and needs a smaller power cord. That would require an inverter to convert 12 volts to 110 (added expense) or a portable power plant (not very practical).
I'd like the entire loader unit to disassemble easily for dismounting, with the main pivot being a simple pipe that drops down over an inner vertical pipe and just lifts off. The inner pipe is welded to a base which bolts to the vehicle frame. The elbow pivot should be of a pintle and gudgeon design so the outer arm just lifts off the main boom. The winch and power cords should be easily detachable.
As for the cradle, that is a whole different project and can be as simple or as complex as one desires.
We'll see if I ever get around to this job. It looks simple, but we all know how things are seldom as simple as they seem at first.
Bill of Materials for 12-foot (approx) Basic Articulated Boom Loader
- 18" of pipe or tubing about 3" diameter or bigger
17" of pipe to fit over the above. Clearance 1/8" max.
35 feet of 1-1/2 x 3/16 flat iron
~2 feet of 1 or 1-1/2" pipe or heavy tubing
~1 foot of a pipe or heavy tubing that fits outside the above. Clearance 1/8" max.
(heavy plastic tubing that fits over one and inside the other can be used as a spacer).
A winch and necessary wiring and controls.
4 grease nipples (zerks) -- 2 for main pivot and 1 for each elbow hinge section
Misc nuts, bolts, welding rod, nylon ties, paint, etc.
- Chop saw
Bit and tap to drill and tap for for zerks
Paint Brush or Sprayer
Grease Gun c/w grease
- Measure and cut out parts: 2 hours
Fitting and Welding: 5 Hours
Grinding and Painting: 3 hours
Install winch and mount loader on vehicle: 3 hours
Miscellaneous fooling around and fixing mistakes, coffee breaks, etc.: 3 hours (min.)
Leveling devices can be added, either by adding legs either side of the vehicle to reduce vehicle tipping or by hinging the main post and adding adjusters, either screw jacks (electric?) or hydraulic. All such devices are more difficult to devise than the loader itself which is a very basic project.