Help - Automated crane movement - motor use

[DKW]

Hi, 

I need some help with a way to use a motor for a MOC crane I’ve built. I want to add some more movement to my city, I already have trains going round the edge, the roller coaster, Ferris wheel, Vestas turbine and carousel, but I want some additional automation in my construction zone. 
 

I cannot, for the life of me, think of a way to use a motor so that the load I attach on the end of the string will move up and down continuously. The string needs to be wound up, down etc etc. I cannot justify the cost of servo motors or going into the Evo side of programming, but I have an array of battery packs, medium motors and selection of gears etc. Happy to purchase specific pieces if someone can give me a clue how to do this. 

I can modify the crane design easily enough, but would like all the gears and motor to be at the bottom which I can hide in another building. Then just have the string going up the centre of the crane, along the boom and then dropping down to hold its load. 

Sorry if this is such a simple question, but I’ve been thinking for ages and can’t come up with a solution. 
 

Thank you everyone! 

Edited November 7, 2020 by DKW

[doug72]

No need for gears.

Use a crank arm that is rotated by the motor. The length of crank arm to be 1/2 of required hook travel.

Attach one end of the cord to the hook & the other end to the end of the crank arm, use small a pulley to guide the cord. 

Edited November 7, 2020 by Doug72

[doug72]

See this diagram uses a micro swith to stop the crane but if you want it to constanly run just use  PF to control the speed.
This gives a dwell at top & bottom of rotation.

Originaly designed for use on a model railway.

Crane Hoist

 

Edited November 7, 2020 by Doug72

[pleegwat]

Another option would be to use a programming belt to control a gearbox, like on this braiding machine by nico71. That would allow more complex behaviours.

https://www.nico71.fr/kumihimo-braiding-machine/

[chlego]

I'll try to build something on Stud.io to illustrate.

Can we just get a picture of the city? I'd love to see it...

Edited November 8, 2020 by chlego

[chlego]

Here's a very basic idea: it's what @Doug72 said (I think):

Attach the string to the end of the white 7 beam.

If you want to, I can make something slightly more complex, but more creative.

Edited November 8, 2020 by chlego
added image

[doug72]

27 minutes ago, chlego said:

Here's a very basic idea: it's what @Doug72 said (I think):

Attach the string to the end of the white 7 beam.

If you want to, I can make something slightly more complex, but more creative.

Yes that’s the best way to make the crank arm.

You need pin with ball end at the end of the crank arm to allow the cord to turn freely.

The hook will need a bit of weight on it to keep the cord tensioned.

 

 

Edited November 8, 2020 by Doug72