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DwalinF

Lift Mechanism

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I have an idea to build lift cabin on the side of a modular building.

Who can help to build or give a link for mechanism that can lift  the cabin up, then stop (or without pause), and then go down. And repeat this cycle. Up-down-up-down...
Thank you for your attention

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How much space do you have?

you can use a scissor lift

Image result for lego scissor lift

you also could use a chain lift ( cant find a picture at the moment )

or you could use a pulley system like an elevator.

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The main question  is that cabine  should change direction by itself. After it up to the top, it should change direction and start go down.

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Maybe you could use the power function switch. When the lift is up to the top, the switch changes the direction of the motor. When it is down, it will again change the direction, and this can be repeated for ever. In this case, you will have to make a system that turns the switch when the lift is up to the top, and the other way around.

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I built a vertical lift GBC machine which has auto change over and cycles up and down using a single M motor that might be suitable for what you require.

Uses an auto change over gearbox drive and rubber cord for drive ropes to the cage / platform.

 

Edited by Doug72

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You could also just use an rope on drum- once the rope is fully down it will spool automaticly up again. On upper side you need a switch to Change direction of Motor.

 

But as i read it again now, maybe this Version is working only 4 times- reversing switch is is tue weak Point in my thought.

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2 hours ago, Hefe said:

You could also just use an rope on drum- once the rope is fully down it will spool automaticly up again. On upper side you need a switch to Change direction of Motor.

 

But as i read it again now, maybe this Version is working only 4 times- reversing switch is is tue weak Point in my thought.

The problem with rope drums winding on and off is that it is not consistent especially if the is more than one layer of rope on the drum.
It is also hard to achieve getting the end points of the hoist correct because of un-even winding of cord onto the drum.
I found this when building tower cranes and used elastic cord and friction method.

If you have space there is a very simple method of operating hoist - that I recall from my model railway days.
It uses a slowly rotating arm, ( 3 rpm), the end of the arm is connected via a cord to the load / cabin,.
As the arm slowly rotates it raises and lowers the load / cabin.
It also has the added advantage of using only a single fixed length cord.
The travel of the load / cabin is equal to 2 x the length of the arm. ( “X-C"
Also the load / cabin slows right down at each end of its travel but speeds up to max. at the mid point.

By using a slightly longer cord dwell time can be achieved when cabin is at the bottom.
Using elastic cord might be possible to arrange dwell time at both top and bottom.

I intend to build a demonstration model show see if this works.

See this diagram. Fig 58 & 59a
Motor /gearbox “A” rotates arm “BB”.
Cord attached at one end of arm “BB”

Lower diagram:
The device shown at “H" has a micro switch to stop the motor each time it revolves once. A push button that bypasses this restarts the moment.

For the application you required this may not be required and arm BB can be shortened to 1/2 i.e. “X-C” shown in lower diagram.

This device might be useful for GBC lifts.


30133399073_2ea4746b4c_z.jpgHoist by Doug Ridgway, on Flickr

Edited by Doug72

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Test rig built to show principle of operation - see video.

click image to view.

 

30470098930_6115cdaa5c.jpg

Edited by Doug72

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My friend Rohan B built a gbc module that has a mechanism perfect for this. It uses the small type technic chain with one tank tread that cycled a dump truck back and forth. 

 

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On 03/11/2016 at 7:09 PM, DwalinF said:

The main question  is that cabine  should change direction by itself. After it up to the top, it should change direction and start go down.

What is the vertical distance you require ?

I have an idea for a cam operated system.

Edited by Doug72

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Very interesting thing to think about......

I remember one compact car that used to reverse direction when hitting by letting the impact pressure make a gear shift. I think such simple thing is what is needed.

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11 hours ago, Doug72 said:

What is the vertical distance you require ?

I have an idea for a cam operated system.

I think like the roof of average modular building... Like about 30-35 cm

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How about something like this?

Not sure if it will fit inside your building though... you need to get creative with the chain location and the connection to the white part.

Edited by Ludo Visser

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1 hour ago, Ludo Visser said:

How about something like this?

 

Ingenious but can't figure out what changes the direction with the motor running constantly one way - can you explain please?

The shuttle goes up and down in the groove but how does that alter the direction - doesn't seem to be connected to anything ?

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After a lot of veiwing the video finally understand how it works after a lot of pauses / run, being able to view at slow speed would make it easier to see the motion.

At the end of the white arm it connects to the chain via a fitting which has a vertical slot.

The extended link on the chain fits into this and it slides up or down as the link passes around the chain spockets at each end thus changing the direction of the white arm.

I set out to devise a mechanism based on this but without using the slotted cam box.

The test rig works OK but needs refining to make more compact and sturdy.

I recall from my days at sea that bridge front windows had windscreen wipers that went back and forth horizontaly.

This was achieved by a use of a chain and a swing arm link to the wiper which run on guide rails.

I have made a test rig to see if this would work - see video.

I used a large catapiller track as easiest to fit the swing link onto.

With the smaller track it is not possible to do this.

I have a short section of old lego track that uses old style red tecnic sprockets which also have two studs on each link to attach a swing link to.

Large Lego Chain link: http://www.brickowl.com/catalog/lego-black-large-chain-link

Checking on line to see if available anywhere

 

Edited by Doug72

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1 hour ago, DwalinF said:

Wow! The last on is great!

Thanks,

Large track links are on order and will then be able to make more compact version.

Will see if I can make GBC lift.

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Large Lego chain links with studs now received and a new test rig built - see video:

Overall it is still fairly large and might be too big to fit into a mondular building but it demonstrates the operation principle.

If I could find away to connect the swinging link arm onto the small track treads it could be made smaller and more compact.

Should be useful for a GBC lift.

Anyone got ideas if that is possible ?

 

Edited by Doug72

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On 04/11/2016 at 9:10 AM, Doug72 said:


30133399073_2ea4746b4c_z.jpgHoist by Doug Ridgway, on Flickr

I have made an updated version of the crank operated system which works very smoothly and consitently.

The operating mechanism and motor could be located out of sight behind a building or beneath it with the cord guided by pulleys.

Gear reduction is 40:1 but can be anything you require, travel determined by the length of the crank arm to give 2 x arm length = lift travel

 

Edited by Doug72

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Good work, Doug, on the Lift, based on the chain.

I've spent a lot of time tweaking my Truck Dumper loop, that Nalyd linked a few posts up.. and the that the main issue you have, in a GBC, (and a vertical implementation like the Elevator), is *balance*

you don't want something lop-sided, that causes the motor/gears to strain unnecessarily..

the horizontal is easy, as the 'weight' is mostly same going in both directions

I've got a couple of prototype scissor lift GBC's, that I'm working on, and it's quite difficult to get it working with zero strain on the motor - something that is a big concern to us GBC'ers who need to run motors for many days, non-stop!

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7 hours ago, RohanBeckett said:

Good work, Doug, on the Lift, based on the chain.

I've spent a lot of time tweaking my Truck Dumper loop, that Nalyd linked a few posts up.. and the that the main issue you have, in a GBC, (and a vertical implementation like the Elevator), is *balance*

you don't want something lop-sided, that causes the motor/gears to strain unnecessarily..

the horizontal is easy, as the 'weight' is mostly same going in both directions

I've got a couple of prototype scissor lift GBC's, that I'm working on, and it's quite difficult to get it working with zero strain on the motor - something that is a big concern to us GBC'ers who need to run motors for many days, non-stop!

Thanks for the comment - have you seen my other GBC lift which uses elastic cord instead of a chain and an auto reversing drive ?

See last post for video.

 

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23 hours ago, DwalinF said:

Want to notice that in  the last MOC Jason Allemann also uses interesting "lift mehanism"

This is essentially the same principle as Akiyuki and uses in the video that I posted a bit up and also in the video of  @Nalyd997 It works well for many applications, obviously! (on a side note: I need to build that plant)

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