Please help.

TimeToShine

i need advice on how to build a pulley system and where to get the materials.
The system is going to be placed between two tables which are 30 cm apart and has to lift a 2kg load using nylon string, the lighter the system the better. One basic pulley won't cut it, because the string is too weak. Could anyone advise me on a suitable design concept for this, and if possible where the hell I can get some pulleys? thanks.

bnt

Some initial thoughts on this:

• pulleys can be any kind of wheel, really - from a model car, thread bobbins, have a look in e.g. the Art & Hobby Shop if you have nothing at home.
• Have a look at the picture I found (below), which has something like what you're after (though not exactly): each half of the string takes half the load, so a 1kg strength string can take a 2kg load. (2:1 pulley advantage)
• This only works if you lift the load straight up vertically: if you arrange things so that the string runs at an angle, the tension in the string will be higher and increase as you lift.
• If you need a higher pulley advantage (e.g. the string is too weak), you need more pulleys in a compound system: see Wikipedia for examples.