Newbie and need some insight

[Jags]

Looking at building a crane that will pick up about 6lbs. I know that is heavy but will need for it to do at least that much weight. Would like for the bucket to reach the top and freely release tension and fall to ground and start process all over again continueously. I want to keep it simple, but would like for this to be done repetitiously. Any ideas from a few of gearheads out there on what I should do. Motor size, and components needed to persue this project. I can't think of a motor that will run a few minutes and then just release on its on. I want the tension to release at a given point is there anything additional I will need to acheive this. Any help would be helpful.

[airman00]

Give us numbers to work with and a diagram.

Does the boom(crane arm) have to move up and down as well?


Also you have to calculate how much torque the pulleys need .
http://www.howstuffworks.com/pulley.htm

Give us numbers - RPM, torque - and then we will be glad to help you out

[ArcMan]

To lift up and then freely release, I would use a clutch between the gearmotor and the cable winding hub.

If you are willing to spend about $80 for one, you can get it at Stock Drive (where I buy most of my small mechanical stuff).

[Admin]

An idea for part of your system . . . use a limit switch as the sensor to detect when its reached the top.