Crawler Crane


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(Click on any image to enlarge it)

Crawler Crane, picture 1

Features

Six electrically controlled functions:

  • Left crawler forward - stop - backwards
  • Right crawler forward - stop - backwards
  • Revolving upper structure
  • First and second winch
  • Boom lifting and lowering
  • Top mast lifting and lowering

This is the tallest model I've built so far. From ground level up to the wedge belt wheel on top of the mast it measures over 1.9 m = 6'3''.
It is fully controlled by pole reverser switches which are fed with currency from a battery box. Because I only have six of them, I had to control two functions with just one switch. That's the reason the first and second winch use the same motor. With a simple gear box you can switch mechanically between the two winches. This plays no matter because you can't use both winches at a time to lift something together. Winch one is for the hook on the main boom and works with a pulley with twelve ropes. The second winch lifts the hook mounted on the top mast with a double pulley.
This way it is possible to lift about 300 gram to the top and about 1.5 kilogram on the main boom.

Crawler Crane, picture 2

The picture on the right shows the two hooks. There you can also see the pulley for the top mast movement. It uses twelve ropes.
The main boom is lifted by two pulleys with sixteen ropes each.
The crane stands on two crawlers, each with two standard LEGO track links side by side. This leads to a good distribution of the weight to the ground.

Crawler Crane, picture 3

The picture on the left shows the construction of the lattice boom. Four 16' Technic beams are connected by diagonally mounted plates of 1' by 8'. The main boom uses 9 of these Technic beams in height.
To balance the forces of the boom, I had to add some counterweight. For this purpose I made six containments with together up to 1.3 kilogram of counterweight. Steel parts do this job without using too much space.
The whole weight of the upper structure lies on a ring of tiles. Therefore the Technic turntable has only to bear the forces of the slewing drive.

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