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  Main cylinders, and crane base.

You will be amazed by the forces at play when lifting the boom, extended and loaded! Initially I wanted to go with a hydraulic solution to this, but it's expensive, and requires quite some space and spills oil. Also: In the event of a hydraulic line failure, having no line break valves would allow the boom to drop to the ground, posing a huge risk.

I then looked around, and found the electrical answer to that: Concens CON35 actuators! They can lift 2200N - each. (Yes, 2200 -- that's 224,34 kgf) I am aiming at 6-7kg load + boom weight + hooks + wire etc. capacity at full boom length (3-4m)
The actuators are locked (<5400N) when the power is turned off, so they even answer my safety concerns.

  The actuators will run on the 12V system voltage, through the dual-actuator controller C2-30.
The controller can be adjusted using a laptop PC, and offers a very wide range of features, for example speed, overload protection, keeping them in sync, end stop control, and much more.
The controller will go on the crane somewhere, and hook up to the RC receiver via an electronic RC switch.

  Actuator data:
Con 35 with 1:71 gearing ratio. Maximum speed 3 mm/s at full load (2200N), max static load 5400N. Stroke is 250mm, max power is 3,6A
Multiply that by two, and you get the power behind the boom!
Data sheets (pdf) are available here: Controller and actuators and more actuator data

  Next is to construct the crane base that holds boom, ballast, and actuators + electronics etc.

I am thinking something like this, in 5 or 6mm aluminum.

  So.. first the base plate in 6mm aluminum. This goes right on top of the slewing ring.

  Then these two aluminum 80x40x4mm profiles form the base of the walls.
Another layer of profiles will go on top later.

  The front end is shaped to seat the actuators. Strong brass adds strength to this structure, so the shaft of the actuator does not 'dig in' to the aluminum over time..which it would!

Note the little hole in the axle end cover on the left side of the wall structure..

  This hole males it possible to push out the axle, thus removing the actuator, without having to remove all axle covers.

 

Brass inserts for the actuators, and the 6mm steel axle.


  The real crane can lift the arm to 83*, so obviously that is a minimum requirement for my crane as well.

Here I demonstrate that the actuators can swing to a full 90*, while 85* would do it.
(Actuators and boom is not mounted in parallel.)
It is always nice to have a little extra room for maneuvering, and not going right to the edge of things.

  Test-fit on the carrier!

  The space between the aluminum profiles will house the winch(es), electronics, auto-wire-winder, and other stuff.
The ballast will go on the end of cause, but the steel structure for this is not ready yet.

Ballast will be up to 90kg - if I can make it work!

  Just for fun: All boom elements, aluminum rings and the now (almost) finished crane head in place!
It is beginning to look a lot like a crane..

     

     

     

    More REALLY soon!

     

     

     

     

     

     

     

     


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