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Building a device which will climb a length of string/wire

  1. Mar 28, 2012 #1
    Hey guys,

    I need to build a simple device that climbs a length of string (about 2 metres) without any support from above, and with energy from only the descend of a 200g mass. Speed is of importance.

    I have considered using two pieces of gears secured onto the string with rubber bands tieing the middles of the gears together. and then, wind the middle part of the gears with strings and attach a mass to the strings. when the mass is allowed to drop, it will give the gears rotational energy and climb up the string, using frictional forces.

    I am wondering if this could work? How can I improve it if it does, and how can I change it if it doesn't?

    New ideas are also welcome!

  2. jcsd
  3. Mar 29, 2012 #2
    If you want to elevate something with the weight of a mass then you need to make sure the the force are balanced, in the sense that the kinetic energy of the falling mass must be enough to elevate the mass upwards. Without this precondition your mechanism will simply not work. After that, i must gears involve additional work regarding frictions and multiplication ratios.

    If you have all this worked out can you give us some more specifics, like mass of the climber, what kind of wire etc
  4. Mar 31, 2012 #3
    Depends, if this is about the UBC contest, it is over and done with.

    If there is some other contest in mind... The centre of mass of the system must head downwards, making gravitational potential energy available to be converted into kinetic energy and overcome frictional losses in your gears, bearings and other bits.

    A light part climbs up while the mass drops. You can easily calculate the maximum mass of the light climbing part by conservation of gravitational potential energy.

    Leave a message if this contest is still a going concern.
  5. Apr 4, 2012 #4
    Look at how a differential chain hoist works. A 200-g weight descending 4 meters can easily power a device that climbs 2 meters of string.
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