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3 hours ago, Aleh said:

Ah, got it. Obviously your tracks have the form like the original real model, not an oval.

Right. My crane is loosely inspired by one of the larger Liebherrs. 

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Hello All,

So I just finished undercarriage mk2. This time i used the medium sprocket wheels, the trackbase is longer and I redesigned the whole undercarriage. The problem with mk1 undercarriage is that it flexed a lot under the weight of the crane body. to make a sturdier undercarriage I used the design of the 42055 BWE undercarriage. the undercarriage is also 4 studs wider. The slewing ring is still the one from the 42082 RTC. The tracks are of a much simpler design, stronger and without tensioner. The drive mechanism is now with a wormwheel instead of a complicated gearbox. The whole base is 5 studs high and the clearance below the base is now 2 studs.

20220330_210920.jpg

This is the bottom view, the batterybox is mounted upside down, with the on-button facing down, but is easily removed, it 'hangs' on 4 points and is held in place with 2 levers. the undercarriage is already quite strong, but does need some more reinforcements.

20220331_123825.jpg

So this is the sideview with the new tracks, a little bit longer, not as bulky a the previous tracks.

20220331_124125.jpg

And last but not least a frontview. The tracks do flex a little bit outward, but the base is quite sturdy. The drive mechanism also needs a bit of work, because it opens up due to the high force on the gear of the sprocket wheel

As always comments are appreciated

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Looks great! :wub:

As for the flex in the undercarriage, I think a 42100-based design would be tougher. I used a modified version for my two cranes and found it can easily hold 4 kg without the slightest bend. See the last three pics here.

Worm-gear drivetrains are best left for really light models, otherwise you gain more friction than torque. I used four motors here but two would be plenty, as is the 6.7:1 reduction. See wip pics here.

1280x960.jpg

 

Edited by suffocation

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Hello all,

Another small update,

On the crawler base I sacrificed 1 stud riding height and I strengthened everything, so as a result no more flex in the transversal direction, only a little bit in the longitudinal direction when there's a lot of load on the hook, or when the boom is down. I geared down the drive gears and I strenghtened everything.

New ballast arrived, so I put in each ballast box, 450g of high density steel ball bearings. Now it has sufficient ballast for normal operation - still  no heavy load lifting -. With the arrival of new parts I could build my luffing boom and with that I ran out of parts again.

20220419_093507.jpg

With the luffing boom in maximum position I reached a height of 2,1m, Even with the ballast of almost 900g, driving and slewing work fine.

I also made a smaller block for the hook to go with the luffing boom. The block also comes with 30g of ballast (high density tungsten steel).

20220419_093603.jpg

Ballast glued with double sided tape (easy to remove)

20220419_093541.jpg

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Here everything is disassembled, with the various choices of hooks. The booms are quite easy to remove into various pieces. The reason i had to disassemble everything is because I had to remove the main winch because the wire got entangled in the drive gears. but it makes for a nice foto. Next project is to make a secondary ballast boom and reinforcing the main boom for heavy loads.

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Hello all,

Here's a new update, I rearranged the configuration. I have now a secondary (ballast) boom. The main boom is now 15 studs longer, and is strenghtened with diagonal beams at all sides. The main hook has again 6 falls. Also a 4th winch is installed in the main boom and is powered with the main battery box.

20220424_150204.jpg

The secondary hook is not yet visible in this foto, the motor of the 4th winch is installed at the beginning of the boom

20220429_204042.jpg

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20220429_210204.jpg

The main boom can be lowered fully using the auxiliary boom. And there is enough ballast to keep everything level, and working. Hope you like it

Edited by gvo25
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19 hours ago, frechettemj said:

Looks good! Do the shock absorbers work well to keep the boom from falling backwards? 

The shock absorbers, do limit the movement to a certain point, but without shocks the main boom can only go to 90 degrees due to the construction of the swivelvpoint

On 4/30/2022 at 9:35 AM, Jeroen Ottens said:

Very impressive!

especially the fact that all functions are working despite the size and weight.

Time for a video?

video is in the workings:thumbup:

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So during the making of the video a few problems arose... So I reworked the undercarriage again. The driven sprocket wheels are reinforced, which result in a better drive and fluent drive motion. I also changed the gearing of the slewing motor and I added a slip gear. I also improved the reinforcements of the underside and the turntable. New tests do show a lot of improvement in drive and slewing.20220501_171123.jpg

A foto to show the upper part of the crane has a good balance, without the base and the ballast weights. more fotos and video coming soon

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