frechettemj Posted March 28, 2022 Posted March 28, 2022 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. Quote
gvo25 Posted March 31, 2022 Author Posted March 31, 2022 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. 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. So this is the sideview with the new tracks, a little bit longer, not as bulky a the previous tracks. 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 Quote
suffocation Posted March 31, 2022 Posted March 31, 2022 (edited) Looks great! 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. Edited March 31, 2022 by suffocation Quote
gvo25 Posted April 19, 2022 Author Posted April 19, 2022 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. 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). Ballast glued with double sided tape (easy to remove) 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. Quote
gvo25 Posted April 29, 2022 Author Posted April 29, 2022 (edited) 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. The secondary hook is not yet visible in this foto, the motor of the 4th winch is installed at the beginning of the boom 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 April 29, 2022 by gvo25 edit text Quote
Jeroen Ottens Posted April 30, 2022 Posted April 30, 2022 Very impressive! especially the fact that all functions are working despite the size and weight. Time for a video? Quote
frechettemj Posted May 1, 2022 Posted May 1, 2022 Looks good! Do the shock absorbers work well to keep the boom from falling backwards? Quote
gvo25 Posted May 1, 2022 Author Posted May 1, 2022 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 Quote
gvo25 Posted May 1, 2022 Author Posted May 1, 2022 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. 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 Quote
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