doug72

Yes to fit Lego straight tracks - see attached drawing. 21/12/15 Drawing ammended to both wheels to have cross hole - allows for alternative gearing to rotate wheels.

See image showing two of the new worm gearbox 3 x 3 x 3 used on a MOC I am currently building of a 1930's mobile crane. Right drives the two wheels, left drives the turn table both driven by M motors. I used 4 worm drives on my Level Luffing Dockside crane to run Hoist, Luffing and Slewing functions at realistic speeds. They took up alot of space - these new compact versions would made that a lot easier. IMG_2957 by Doug Ridgway, on Flickr

This is how I build driven and non driven crane bogies to run on straight 3228 track. The white wheels have had the grooves widened & deepened to fit the track profile. The double bevel gears catch on studded plates on which the track is fixed so track rail has to be raised using 1 x 2 plates to avoid this 16T gears would be better - looking for a narrower track wheel with intragal gear with cross axle hole 1L thick if possible. IMG_2956 by Doug Ridgway, on Flickr

That new turntable design looks very useful for crane builders - will definitly be getting this in the New Year. Some bogie wheels to use on LEGO Straight Rail with No slots and No Notches (3228) would be useful with double flange to suit. Plain version with pin hole 1L thick x 14 dia. and another version with cross hole with integral 16Tgear on one face, 2L thick x 14 dia.

It will pull apart but its quite a tough - the two bosses on the internal part into which the screws go, click into a small recess and once screws removed found if pull each side alternatley it finally pulls apart. Its easy the 2nd time. No batteries were harmed during this process !!

Milan used this part as a turntable ring for his TC8 crane entry. http://www.brickowl.com/catalog/lego-round-brick-13-667-x-13-667-fabuland-hollowed-4750

I.ve had problems in the past with PF control "apprently" not working when using a transmitter / receiver set up for PF motors. Nearly always traced to the cable connectors not coupling together properly - it only needs one of the 4 connectors in the cable plug not the touch its corrosponding connections for the system to fail. As in my post on the other post on this topic - with power off gently use a thin pin between each silver contact and the plug case to ease it out a little bit - then try again, do this for all 4 contacts in both the male and female cable plugs

Make sure the cable plugs are seated onto the terminals firmly. Using a small pin ease out slightly the four silver connectors on the female cable plug and try again. Sometimes they fail to make contact with the silver connectors on the male socket on battery or receivers.

Problem I find with 3L wide differentials is the axles keep pulling out of the 12T thin bevel gears. I haven't got space to use the out rigger arms that are normally used to stop this. On the old version 4L wide you could use 1/2 bushes to stop this. I need to mount a pair of wheels at minimum distance apart for a powered caster steering unit I am building. Only option I see is to cut away the centre block on a 3L diff to allow 1/2 bushes to be used.

Look on this site:- http://www.brickowl.com/search/catalog?query=string I recently brought 2.5m. p/n 14728 medium thickness from a UK site.

Zblj: thanks for that - tried it and works OK. 12T double bevel meshes with turntable on a horizontal plane on same axle a 8T gear is added which meshes with an 8T gear on servo axle. IMG_2918 by Doug Ridgway, on Flickr Coles-mobile yard crane- by Doug Ridgway, on Flickr

I want to use a servo motor to turn a 28Z turntable for caster steering for a 1950's mobile yard crane I intend building. Due to gear tooth alignment on the turntable and 12T double bevel gear it is not possible to get the pair of wheels to centre correctly to straight ahead. Note: the servo motor is corecctly centred. Only alternative I can think of is some sort of lever linkage. Anyone got ideas how to overcome this ?

This seems to be a common problem with PF motor leads breaking at the point where the ribbon cable enters to motor housing. I now try not to flex this section of cable when possible. I have had it happen on M & XL motors. A redesign by Lego is required to prevent this.

I use braided cord used for stringing beads obtainable from craft shops or on line. Comes in a variety of diameters and colours.

Efferman: the one piece version for 8 & 24T gears is spot on and allows for a directly coupled M or L motor. Had a lot of problems building my TC8 crane and the latest I am building with the worm being slack and shifting back and forth. I'll be placing an order soon Thanks Doug72

Thanks - that looks ideal - nice and compact. Doug72

Looks good - with worm braced OK. Axle through lower hole for 8T gear / middle for 24T gear and top for 40T 40T gear not often used, so a version that just caters for 8T & 24T gears would be ideal. How is the rear part for axle attached to main part ? Can you show an image of the other side. Thanks

A split worm drive gearbox would be a great addition to replace the 32166 part. http://www.brickowl.com/catalog/lego-block-connector-with-one-half-of-wormed-gearbox-32166 I can't figure what the half 24T gear is useful for ! Say 3 x 3 x 5 suitable for 8T / 24T / 40T gears with pin holes to suit mounting with studless technic.

Back in late 1950,s i received a No. 9 set for Xmas ans spent many hours build models with it. We even had a shop in the town where I lived that sold only Mecanno. Saved up for weeks to buy extra long angle beams to make tall cranes. Never managed to upgrade to a No.10 set - top of the range but I have a reprint of that instruction book. I have built a Lego version of the Giant Block Setting Crane and currently trying to build a version of a Dockside Level Luffing Crane. Lego has its limitations when building a version of a Meccano super model. i.e beams are only 15L long - a 30L and compact worm drive gear boxes to suit a range of 8T / 24T / 40T gears would also be uesful to Studless Technic standards. Even had steam or electric power. Meccano has a degree of flex in its componants - Lego doesn,t. Trying to replicate a jib that tapers in two directions has taken quite a while before it looks OK.

Have built both of them and added a motor to the hoburn coupling - fascinating to watch

That's how i built my two working copies. The Parox gear one is the hardest to figure out.

Think of it as a series of shaped levers with the ones on the input axle pushing those on the driven axle..

Using the videos as a guide have built both of these, took awhile to get the Paradox one to work. The Hobson coupling isi facinating to watch.

Worm drive problems !!! Having sorted out the geometry for the luffing rope system I found the drive to the jib cranks was jumping a gear tooth as the jib reached the maximum raised position. Also there is a lot of backlash in the worm drive as cranks went over centre the jib arm jumped to new position taking up backlash in the other direction. Worm gear is a sliding fit on axles meaning use of bushes to keep it in correct contact. So a re-think on how to drive jib arm cranks - eventually used a 6588 gearbox which has an enclosed worm and 24T gear. Thin side plates are required to allow the gear box to be correctly alighned on studless technic beams. Motor had to be raised 1L to accomodate the new drive. Success - jib raises and lowers smoothly at last and as an added bonus now have two beams on on top of the L motor on which to mount the hoisting motor and rope drum. Have ordered some 32166 half worm housings which use 24T gear and have correct pin hole spacing for studless beams.

More progress : The geometry for luffing the jib after a lot of trial & error finally achieved. Machinery house base narrowed by 2L and lowered by 1L by repositioning the gantry drive gears to prevent slewing gear fouling them. Slewing motor now mounted vertically to give more space for rope hoist unit. Luffing motor changed to a L motor for more power with a double worm reduction of 8:1 then 12:1. Note: 12:1 reduction achieved by using two 12T double bevel gears meshing with the worm gear (see Sariel’s excellent Technic Builders Guide - page 49, Fig. 5-12.) A 20T double gear meshes with one of the 12T gears which in turn turns the two crank arms. Jib arm: this caused a lot of head scratching as the arm has to taper towards the jib head in both directions requiring a compound connection at the jib base. Jib will be better colour co-ordinated once extra grey 15L beams arrive. Still waiting for the Lego wheels for gantry. Next step is to determine the geometry & height for the tower for the “Toplis” level luffing rope system and build the rope hoist drum unit. Two views of progress. IMG_2723 by Doug Ridgway, on Flickr IMG_2722 by Doug Ridgway, on Flickr