[HELP] Pulley System

[Sir_Samsalot]

Hello. Before I begin, I want to warn you that this is my first post. Also, this is my first time of really getting into MOCs with Technic/Mindstorms, so I'm not very well acquainted with a lot of the mechanical aspects like torque and gear ratios. I apologize for this beforehand.

Apologies aside, I present to you my incredibly-unfinished WIP automated warehouse system, inspired by this setup:

Unfortunately, I only have the transporter built that will transfer things from the loading/unloading area to the actual storage area. Here's some pictures:

Perspective view

Side view

Bottom view

Demonstration of the transporter's "grabbing" mechanism

I built this section without very many issues, until a major problem ground the project to a halt: Developing a pulley system strong enough to lift the machine and its cargo. My current plan is to use either a two-pulley or four-pulley system that connects to both sides of the transporter, although (as I mentioned at the beginning), I am not very well-acquainted with torque, gear ratios, etc. So, I turn to you all for help: How would you go about designing a pulley system to lift the most weight possible? Any tips for minimizing weight on the actual machine itself? I'm also open to any suggestions for the project as a whole.

Also, since materials are likely to be an issue, here's another picture of the motors and large gears that I own that are not currently in use on the transporter.

(I know, it's a tiny amount of stuff, but I have some money to spare to buy extra gears and motors where needed)

Thank you!

[Alasdair Ryan]

I would try using the a nxt motor connected to a pulley on each side (four in total),this should have plenty of power to lift the bins of parts.

[Sir_Samsalot]

Hi,

I'm not entirely sure what you mean. Are you suggesting a single NXT motor with four pulleys connected to it, or four NXT motors each with their own pulley?

Edited May 25, 2014 by Sir_Samsalot

[dhc6twinotter]

You can set up a block and tackle (multiple pulleys) to lift heavier loads. You can set up as many pulleys as you want. Each pulley will give you additional lifting capacity, but your lift speed will also be slower, plus you will need longer string.

Here's a bit more info:

http://en.wikipedia.org/wiki/Pulley

A good video:

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There is a video floating around of a Toyota Land Cruiser with a 2500kg winch pulling out a 51,000kg excavator. They used a compound winch setup and two addition pieces of machinery as anchor points. Here's a link about it from another forum I frequent: http://www.ultimatey...ound-winching�� If you are a member of Yuku, you can view the video here: http://tow411.yuku.com/login/loginnow/

Anyways, you can also use gears to get more torque on your drum. A small gear on your motor and large gear on your drum will give you less speed and more torque (lifting power in this case). You could use multiple gears together for more lifting capabilities. Worm gears also provide more torque, and they come with the added benefit of not being able to be back driven (your load won't unwind your drum and motor).

In a nutshell, if I were building a crane, I would use all of the above together. I would use a block and tackle setup on the line, gear reduction between the motor and drum, and a worm gear to prevent back drive.

Edited May 25, 2014 by dhc6twinotter

[Alasdair Ryan]

Hi,

I'm not entirely sure what you mean. Are you suggesting a single NXT motor with four pulleys connected to it, or four NXT motors each with their own pulley?

I meant using one nxt motor linking four pulleys,you can incorporate Daniel's idea above into this too.

[Sir_Samsalot]

I meant using one nxt motor linking four pulleys,you can incorporate Daniel's idea above into this too.

Alright, thanks for clarifying.

What if I tried using my PF motors (since I have more of them) to increase the crane's speed, and then connected the motors to my Mindstorms brick with a setup like this:

My only worry with this setup is slow response times. What do you think?

[Alasdair Ryan]

Since you will be "lifting" stuff I would use a PF XL motor.

I do not have any of the newer NXT parts so I can not be sure, but I would think there would be little difference in response times when using PF motors and NXT motors together.

[Sir_Samsalot]

Since you will be "lifting" stuff I would use a PF XL motor.

I do not have any of the newer NXT parts so I can not be sure, but I would think there would be little difference in response times when using PF motors and NXT motors together.

Okay, thank you.