[MOC] 5 axle mobile crane - finished 02/2019

[Ivan_M]

Weekends are favourable to building so I have some progress of cabin:

I have made the front from tiles and slopes because the technic panel is just too rough. It also allowed me to put there screen wipers and front hitch.

[letsbuild]

Very clean build, I like it!

[Ivan_M]

The second pair of racks finally arrived so I could test the whole setup of outridges, see them in action in video:

The problem is that the rear outridges are driven from front and the friction is quite high in whole system resulting in jerky movement. A second motor to power them would be better

[gate]

Nice progress. Solution for pneumatics - may be adding an airtank 67c01 could help, and then adding valve after it. It might solve the problem with not simultaneous deployment.

As for 1 axle drive - do you think it will be enough to move it?

Edited October 23, 2018 by gate

[Sariel]

16 hours ago, Ivan_M said:

the whole setup of outridges

The word is outriggers. Pardon me, but you keep using the wrong word.

[Ivan_M]

52 minutes ago, gate said:

Nice progress. Solution for pneumatics - may be adding an airtank 67c01 could help, and then adding valve after it. It might solve the problem with not simultaneous deployment.

As for 1 axle drive - do you think it will be enough to move it?

Thank you. The air tank will not help, the delay is partly due to various length of tubbing and mainly due to different friction of cylinders, some are more than 20 years old. I have tested the drivetrain with 2kg of load and it driven fine, you can see it on previous page.

Just now, Sariel said:

The word is outriggers. Pardon me, but you keep using the wrong word.

Oops, thank you, I have to keep that in mind.

[Ivan_M]

Never call anything "final", before you test it out throughly. So I had build boom in full length and glory - 6 wide, 7 high, 66 studs long, 4 section, almost direct copy of this boom from Nick Barrett:

from this crane: http://www.moc-pages.com/moc.php/443667

It looked like this:

Boom 7x6 4-section

It works very smooth when short, reasonably smooth when 30 studs long, but impossible to extend when 66 studs long using PF motor ( VERY geared down). The problem is 3rd section made of smaller panels. It bows significantly because it is build from small parts next to each other. It is difficult to describe precisely, but the section is not flat, but curved. This creates a lot of friction when it slides in or out of the 2nd stage, because it have to bend to opposite direction. I have damaged several parts trying to extend the boom by string and finally decided to rebuild it. I would like to see how Nick's boom performed, I don't think that he was able to extend it using string only, without the help. Maybe I'm doing something wrong. I have to say that the fully extended boom looked more than impressive, total height was around 240 studs (~192 cm). So it was clear that I have to do something about that and obvious solution was to a) reduce section to 3, b) remove the section with most friction. I have left the first and second section as is, only reducing width by 1 stud as it wasn't needed. The 3rd section is left out and former 4th section is made bigger to fit into 3 brick high panel. I have also added pulleys to 2nd section end and front and to 1st stage front so the string can slide easily. Final boom is 5 studs wide, 7 high, 66 long, extends to ~180 studs (144 cm). Not as impressive as 4-stage, but still nice.

It looks like this:

Boom 5x7 - 3 stage

I also had to totally change lifting cylinder, the string operated one wasn't strong enough and string tend to "cut" into parts when it slides over them without support of pulley. It is nothing different that good old rack and worm gear, held together by some plates. Works like a charm. It is a little bit too wide compared to 5-wide boom, but that is lego..

20181029_233900

You can also see some basic structure that will form superstructure, I have three L motors there - one for slewing - worm gear to 20t bewel and 12t bewel to turntable, other one for rising boom - 12t bewel to 20t, then worm on rack, last one for boom extension, with worm to 8t and second seto of worm to 8t. Ther will be 4th motor as well for winch.

Video of the boom is here, with some surprise at end:

Boom fully extended:

Boom 7x5 3-section

[Aleh]

To prevent bending so long boom highly recommend to create Y-arrangement! 

Nice WIP, BTW!

[zoo]

I would try a boom design where you have support at the rear end of a boom section. Lots of unnecessary friction otherwise. Not sure what the cross section looks like in your design though so maybe you already thought of that.

[mitx2529]

nice try!! it seems like 4 section booms have many problems to solve.

l also love the 4 section booms, especially extend with string. 

How does it work? does it shrink when it nearly horizontal ?

 

 

[1gor]

Boom size is impressive 

[Ivan_M]

Soo after very long time I have finished it. I had to take a brake from it because of the lack of motivation. In the end most of the functions work, but not without stressing parts. I guess I had overexpectations about some key parts (boom, outriggers), but I have learned important lessons about crane building. Please excuse the pictures, my dslr failed just right before shooting and I'm left with phone only at the moment.

The final spec are:

Undercarrige:

L-motor for drive, 3rd axle is driven, connected to V6 engine

Servo motor for steering, alxes 1&5 and 2&4 have same steering angle, all axles feature ackerman geometry

M-motor for extending outriggers

M-motor for powering autovalve and pneumatic compressor, it is possible to lift the crane from ground, but not without parts stressing

Upperstructure:

L-motor for boom lifting

L-motor for slewing

L- motor for boom extension, extension through wire

M-motor for winch

Detachable counterweight

Whole album: https://www.flickr.com/photos/89695600@N07/albums/72157689610896333/with/46339523814/

20190210_160128

20190210_160035

20190210_160605

20190210_160740

20190210_161805

20190210_162320

 

Edited February 11, 2019 by Ivan_M

[Aleh]

Looks complete and beautiful! Only bad fully extending boom is blending, so no heavy loads possible.

 

[nerdsforprez]

One of the cleaner cranes i have seen. Well done. 

[mitx2529]

I like the boom , it's beautiful and funtional , can it retracted when it nearly horizontal 

[suffocation]

Wonderful, wonderful build Still trying to figure out where you crammed all the motors.

[Ivan_M]

1 minute ago, mitx2529 said:

I like the boom , it's beautiful and funtional , can it retracted when it nearly horizontal 

Yes it can retract in (almost) every position, it is operated by two strings winded in opposite direction. While the first one is winded in the second is released.

1 hour ago, Aleh said:

Looks complete and beautiful! Only bad fully extending boom is blending, so no heavy loads possible.

 

Thank you, yes it is not able to lift anything

1 hour ago, nerdsforprez said:

One of the cleaner cranes i have seen. Well done. 

Thank you!

[TinkerBrick]

This is one cool crane.
This custom linear actuator is quite interesting. I wonder if you could provide some more detailed images?
Especially the mounting on the upper carriage interests me a lot.

[1gor]

Design is very clean and whole creation looks very smooth 

[Ivan_M]

11 hours ago, TinkerBrick said:

This is one cool crane.
This custom linear actuator is quite interesting. I wonder if you could provide some more detailed images?
Especially the mounting on the upper carriage interests me a lot.

It is already disassembled by you can see one picture of it here:

But of course it was already invented before, I got my inspiration from Dirk Klijn:

Liebherr LTM 1090 4.1 - Sarens by Dirk Klijn, on Flickr

What is different is the mounting, Dirks version ends with XL motor that rotate together with the accurator. In my version the accurator ends with

. It is attached to the centre of the turntable like this:

 

[TinkerBrick]

@Ivan_M Thanks a lot for those images. They'll help me a lot. I'm trying to built a slim custom actuator for the GMK6400.

[mitx2529]

On 2/12/2019 at 6:04 PM, Ivan_M said:

Yes it can retract in (almost) every position, it is operated by two strings winded in opposite direction. While the first one is winded in the second is released.

Thansk for share, i will try to modify my crane.