Engineering Semester project, help? ideas?

[fox racer]

Its the end of the semester and my engineering (mechanical) semester long project is due. The task is to build a machine to lift as heavy a weight as possible (starting off with 1.25Kg weight) a distance of .25m. I have attatched my plan to do this using pulleys and a wood structure (only allowed wood, pulleys, nails and screws, and an oil lubricant). My question is, in order to lift an object, how does pulley size affect the lifting force? what about the amount of pulleys or how many times its wrapped around a pulley? Since its a competition, i think i have a pretty good chance in these runnings, but what do you guys think? anything you would change? Finally, the most important question, home depot and no where really online has these pulleys, where do you think i could get my hands on some cheap pulleys say 1-3 inch diameter?

 

[ryan218]

the more pullys there are the better. the more pullys it has the less load it has to pull.

what is this? like whos will pull the most weight before breaking or something?

and to get the pullys id try a hobby store? maybe they will have it or a arts and crafts store.

 

[fox racer]

yea it kinda is a competition, but the only requirement for a perfect grade is to lift 1.25 Kg, .25m high. anything more is pretty much just showing off haha.

 

[ryan218]

yea it kinda is a competition, but the only requirement for a perfect grade is to lift 1.25 Kg, .25m high. anything more is pretty much just showing off haha.

yeah just don't put it off till last minute. i did that and was scrambling to get mine done.

 

[dgollem]

Try some snattch (sp) blocks the 4 wheel drive folks use to winch out thier rides.

 

[HISSIN50]

If there's no limit on how far the counterweight can be displaced, it should not be too tough.

Have fun!

 

[5.0 con-vert]

Go to a west marine or boaters world and get some blocks that we use for sailing. They are small and high ratio and will be perfect for that stuff. I use them to lift myself up to do repairs all the time. The more the better and the more times around, the easier the load is to move.

 

[srothfuss]

Here is some basic stuff on Pulleys... It should give you a few ideas. It would be pretty cool if you threw in a block to hold the rope (thus holding the weight in the air)

Edit: forgot the link http://www.swe.org/iac/lp/pulley_03.html

And another good page with some forumation stuff for you - to provide a report for your design... http://en.wikipedia.org/wiki/Mechanical_advantage