Crane Design

 
 

How the Mechanism Works:

Our crane utilizes a truss/beam combination to support the cylindrical weight at the end of the beam.  Attached to our closed, triangle beam is our servo motor, which is bolted to a notched lever arm, which rotates to lift the weight.  When plugge in, the servo motor rotates, lifting the weight up the column.  The entire structure is made out of flat strips of aluminum, which were bent using a bending break in order to increase their ability to resist buckling.  Our truss uses a minimalist design, which was reinforced with cross-beams where stresses from lifting the weight were strongest.  By using this approach, our group was able to keep the weight of our crane down, and use more material where it really made a difference to the structure. 


Interesting Design Aspects/Features:

There are multiple aspects of our design which particularly lead to its success.  One of the most influential was the closed, triangular beam used to support the servo motor.  Originally, our group had planned to use an I-beam to support the motor because of its efficiency in bending, but this beam could not remain rigid while the servo was in operation.  Therefore, we switched to a triangular beam, which could resist the torsion from the motor. 

 

Pictured: (left) truss structure of crane (above) bending break used to shape aluminum strips.  (below) edge of beam, along with servo, and notched rotating arm

This beam was supported by a flat piece of aluminum, bolted vertically to our structure.  We used this unorthodox arrangement to decrease the unsupported length of the beam, ensuring that it could operate despite the bending stress.


Another important an innovative aspect of our crane design was our method for attaching the servo motor to our beam.  Originally, we used a simple bent strip of aluminum, but this strip deformed too much when the servo was in operation.  So, we cut two small L’s from a thicker piece of aluminum given to us.  These two small L’s were able to rigidly lock the servo motor into place.


Pictured: (above) vertical aluminum strip screwed to truss base which supported triangle beam  (right) L-shaped aluminum pieces used to securely fashion servo to beam