doug72 Posted October 5, 2015 (edited) Follwing the succesful build of a horizontal jib - I set out to build the rest of this tower crane. Tower is Red as thats the most parts I had in one coulour to build it - jib yellow for same reason. Took four re-builds to get the Z60 turntable, winding drums and drives to them to work smoothly. All fitted into a 5 x 7 x 11L space on top of the turntable. Hoist trolley travel took a lot of time to devise and get to work smoothly. - had to resort to studded technic beams with flat plates for wheels to run along. The traversing system uses only a single "special" rope. Counterweight consist of an empty 88000 battery box filled with a heavy lead weight - hence not entered into contest. IMG_2606 by Doug Ridgway, on Flickr Edited October 5, 2015 by Doug72 Share this post Link to post Share on other sites
Milan Posted October 5, 2015 Will there be a video? I would love to see the trolley move. Looks very nice! Share this post Link to post Share on other sites
doug72 Posted October 5, 2015 Will there be a video? I would love to see the trolley move. Looks very nice! Only just finished it - I will post a video later. All three movements possible at the same time: Slewing, Hoisting, Traversing trolley. I,m on the verge of dismantling my ultimate 42009 mobile crane in order to build more static cranes. Releases 8 PF motors / 4 PF Rx and loads of parts. On the lookout for metal crane hooks - on my Xmas list !! Share this post Link to post Share on other sites
doug72 Posted October 5, 2015 (edited) Here's the video - best without sound !! MVI_2607 by Doug Ridgway, on Flickr Only one problem is tower twists slightly when slewing the jib arm - can't find a way to brace it to stop this - any ideas. Doug72 Edited October 5, 2015 by Doug72 Share this post Link to post Share on other sites
doug72 Posted October 6, 2015 Note: The white 24T clutch gear that can be seen rotating - in the video - as trolley traverses is not really necessary as the over travel is protected by other means. Share this post Link to post Share on other sites
doug72 Posted October 6, 2015 Hoist Trolley traversing system: During the tower crane build I could not find a suitable drive pulley that fitted the space available and still be Lego legal, so I modified p/n 13971 18 x 7 narrow rim by drilling the pin hole to accept half axle bushes which bonded in. ( Shown on left side of photo) I had several 55981 wheel hubs 18 x 14 - which have two grooves but have a plain pin hole - so also not suitable as a drive pulley. Finally found I had one 55982 wheel hub which has a axle hole and two grooves. (on right of photo) IMG_2608 by Doug Ridgway, on Flickr Crane now fitted with legal parts as shown and 24T clutch gear replaced by a normal 24T gear. IMG_2609 by Doug Ridgway, on Flickr So how does it work - the secret is 2mm braided elastic cord. The groove in the 55982 wheel has enough friction to drive the cord and hence the hoist trolley. Correct tension has to be found by trial & error and adjusted at the hoist trolley. When trolley reaches each end of travel the cord stretches until it slips or drive stopped. Effective without use of double drums or cords getting tangled due to uneven winding of cord onto the drums. Share this post Link to post Share on other sites
doug72 Posted October 8, 2015 (edited) I was not really happy with the rotation of this crane due to erractic rotation when slewing the crane jib using an offset drive via universal couplings to the 12T bevel gear meshing with the Z60 turntable. The erratic motion is caused I think is due to the universal couplings. The alternative suggestion for a straight run using bevel gears has to much friction. I have therefore reverted to using a Z56 turntable. The Z56 turntable allows a straight run for the drive shaft up the side of the tower and use of a 8T gear to mesh with turntable ring. Overall gear ratio for rotation now 168:1 Photo shows set up on my TC8 Luffing jib tower crane IMG_2577 by Doug Ridgway, on Flickr Edited October 8, 2015 by Doug72 Share this post Link to post Share on other sites
Kelkschiz Posted October 9, 2015 I like it a lot. It looks and functions smoothly and realistically. Very nice. Share this post Link to post Share on other sites
Jeroen Ottens Posted October 9, 2015 I was not really happy with the rotation of this crane due to erractic rotation when slewing the crane jib using an offset drive via universal couplings to the 12T bevel gear meshing with the Z60 turntable. The erratic motion is caused I think is due to the universal couplings. The alternative suggestion for a straight run using bevel gears has to much friction. I have therefore reverted to using a Z56 turntable. The Z56 turntable allows a straight run for the drive shaft up the side of the tower and use of a 8T gear to mesh with turntable ring. Overall gear ratio for rotation now 168:1 Photo shows set up on my TC8 Luffing jib tower Have you oriented the two universal couplings in an aligned way? You can orientate them in two ways, one straight and one where they are rotated 90 degrees with respect to each other. That is the wrong way, and will give you a non-uniform rotation output. I hope this is a clear enough explanation? Share this post Link to post Share on other sites
MajklSpajkl Posted October 9, 2015 (edited) Have you oriented the two universal couplings in an aligned way? You can orientate them in two ways, one straight and one where they are rotated 90 degrees with respect to each other. That is the wrong way, and will give you a non-uniform rotation output. I hope this is a clear enough explanation? It is clearly visible on the above photo, that those universal joints are not aligned properly... Edited October 9, 2015 by MajklSpajkl Share this post Link to post Share on other sites
doug72 Posted October 9, 2015 (edited) Thanks for that info. Forgotten about that !! Have changed back to a Z56 T/T for the tower crane and just changed the slewing drive for my TC8 Luffing Jib Tower Crane (with Z60 T/T) to a straight drive and now both slewing smoothly. Will try your suggestion just to see if it does make a difference. Edited October 9, 2015 by Doug72 Share this post Link to post Share on other sites
doug72 Posted October 9, 2015 Have you oriented the two universal couplings in an aligned way? Thanks for that tip - now tried it on my TC8 crane and working well - universal joints are located at base of tower and then direct drive up the slewing 12T gear. Even managed to get a support for the angled shaft between the two UJ's. Much tider looking solution. Share this post Link to post Share on other sites
doug72 Posted November 9, 2015 (edited) Improvements to Tower Crane: Both this tower crane and the TC8 contest entry tower crane had the three drives running up the outside of the tower something I was not really happy with. I have now modified the horizontal jib tower crane so that the three drives are contained inside the tower. The structure of the tower had to be re-designed to allow the drives to pass through and this has had the added advantage of making the tower more rigid with less tendency to twisting when slewing the jib. This meant the three motors had to be re-positioned on the base unit along with their right angle drives. Hoisting & traversing drives pass up through the turntable. The slewing drive requires a short universal joint section to the reduction gearbox again contained within the tower. Drive for slewing is via a compact 64:1 reduction gearbox then an 8T gear driving the Z56 turntable giving an overall ratio of 448:1 If 1L worms gears were available an even more compact double reduction gear box could be built. Base unit showing the three M drive motors, right angle drives and the drive shafts. IMG_2714 by Doug Ridgway, on Flickr Side view showing slewing reduction gear box. IMG_2715 by Doug Ridgway, on Flickr Next step is to modify the Luffing Jib Tower Crane. Edited November 9, 2015 by Doug72 Share this post Link to post Share on other sites
