doug72

Re Wacky Wheels contest: The contest rules clearly state:- The contest might be closed later than the deadline. Don't complain about this not being fair.

Conveyor modular construction: Uses multiple 11L units designed to give a smooth surface for track belt to prevent snagging in loaded direction or sagging on the return direction. Each unit linked by beams along top edge.

Thanks, The initial conveyor boom was only to determine angles & pivot points etc. Built using 11 x 5 frames but conveyor belt can snag so re-building using a similar arrangement that I used to guide the chain belt on my BCE. I have developed a standard boom unit based on 11 x 3 panels which provides very smooth passage for the conveyor belt. Photo to post later, sun shining so off out on my bike. Will probably use a straight boom with a short cranked section at the top - trying to get a curved boom not easy and prevent ball rolling forward from the lift pins. Its a challange to sqeeeze in all the various drives & gears etc. in space available. I wish there were linear actuators that had a longer travel and I don't have the new long pnuematic actuators, which mean a compressor would be required. Might try a rack system as used on teleschopic crane booms.

Progress Update: First part of conveyor made with two linear actuators to raise and lower the conveyor boom. Underside of conveyor belt supported by rollers to keep it clear of any obstructions.

 Same problem as per my Bucket Chain Excavator, the conveyor belt needs to bend slightly backwards to drop down to the loading hopper. 
Large yellow sprocket is in approx position to drive conveyor and load from hopper which to be devise next.
 Short conveyor boom in use at the moment for testing that drive and loading of GBC balls works OK. Once OK conveyor boom to be to be extended further with a rotating spout at the discharge end. Another problem yet to be tested is when doing radius turns the wheels on the two caster units need to run at different speeds or the tires will scuff - at the moment all wheels driven at same speed by one motor. When wheels are parallel to each other there is no problem. So I will test by removing drive to the smaller caster unit or install a differential somewhere in the drive chain but no space to do this !

When dis-assembling MOCs I always take care to remove these sort of parts gently and pull axles / axle pins out with needle nose pliers to avoid twisting which can cause them to break.

I,ve had a few crack but not break. The cracked ones can be repaired using ABS liquid glue by using a needle to place a small drop onto the crack and then squeeze the part together. used the same repair method on other parts that hace and axle hole at end of half beams, angle beams etc.

Weak Crown gears eliminated. Transfer gears using 24T crown gears = 4.2:1 to drive wheels. Revised transfer gearing using bevel gears = 3.85:1 for wheel drive. Also eliminates the two Black Beam 3m Ø4.85 with fork (87408)

Yes travel speed was too fast using 12/20 bevel gears so tried crown gears to get 3:1 reduction for slower travel speed. Might put bevel gears back in and add more reduction from XL motor or use 36/12 bevel gears.

Design of caster steering units achieved to give firm support for differentials and wheels using 48.5 x 20 tires. I have decided on an eight wheel arangment rather than 16 wheels to keep overall size down & reduce number of parts required. Mobile base unit made:
 Separate M motors provide steering for the large and small steeringlunits via 60:1 reduction. This allows for all modes of steering, normal, crab, radius and also allows for sideways travel. XL motor drives all eight wheel via 4.2:1 reduction. Steering will be controlled by PF speed controller and 1 x PF Receiver. Next stage: build conveyer boom with either manual or powered height adjustment.

After making four caster units and making a mock up have realised that to build a crane with four caster units instead of six it will still be massive even with using smaller tires and probably don't have enough parts. Therefore will build a mobile shiploader with conveyor instead, might even use some pnuematics for the lifting boom and bogie jacks. Possible use it as a GBC module.

After a lot of trials to determined the best option for steering & drive, the caster units are paired in a four wheel layout. Left & Right at rear / left & right at front. 
Mark 1 steering & drive unit. Each steering unit has a separate M motor turning two caster units.
 Steering reduction = 46.66 : 1 
 This arrangement will allow for all steering options using one PF receiver.
i.e. normal / crab / radius turns and also allow movement sideways. Built using Z28 turntables, steering proved easy to achieve but not the drive to the wheels as can only be via red connecter above or via right angle drive meaning any rotating structure above would require a large clearance of at least 3L. Outside width of wheels = 11L Mark 2 steering and drive unit.
 Some layout as Mark 1, paired caster units at rear and front. Built using a Z60 turntable which allows for both steering and drive inputs to be kept low and allows for any rotating structure above to only require 1L clearance. 
 It was a little bit tricky providing good support for the drive axle for 20T double bevel gear for the differential but finally sorted. Overall height of unit same as Mark 1 Steering reduction = 100:1 giving an ideal slow speed. Wheel overall width increased to 13L. P.S More tires on order. Next step: Build matching pair of caster units and figure out how one XL or L motor can drive all four caster units.

Cross bracing (Red beams) now added to prevent beams coming apart from differential, happy with the result. 20T double bevel gear better supported. Next step build another unit and order some more 42.2 x 20 tires to complete a set of 4 or 6 units. Then work out how to steer all of the caster units together to allow for normal / crab / raduis turns. Possibly using two M motors each steering a pair of caster units. Still undecided which to build, the crane or converyor ship loader, both have complicated drive arrangements.

Looks great but how about building this ? A double bunk bed that converets into a 3 seater sofa. A real challange.

Thanks for all the feedback and suggestions. On a previous MOC with a single caster unit I built it using a LEGO Beam Frame with Large Ball Joint (92910) and a large Z56 turntable. On the real machine the wheels are hydraulically driven. It would be simpler without a differential but when a caster unit turns while machine is not driving the wheels actually rotate in opposite directions - this allows the whole machine to manoeuvre and position itself in very constricted surroundings. My latest version seems strong enough for intended purpose, but I will see if can add some cross bracing.

You , 62.4 x 20 tires look too big, using them just to sort out how to build for the caster unit for drive and steering. I have enough 43.2 x 22 tires to build 8 caster units which maybe wil look too small. Best size seems to be 49.5 x 20 tires but only have 4 pce.

Liebherr have a factory not far from where I live in the UK which has whole range of cranes being being assembled and tested outside.
 I can view them from the opposite bank of the R. Wear where I cycle along the C2C route. My MOC will be a representation of such a crane but not an exact copy. I plan to start with the base mobile support unit and work upwards. This is also another possible MOC contender using the caster units which could be converted to a GBC module. https://www.youtube.com/watch?feature=youtu.be&v=5SyurvGDxFw&app=desktop

Thanks - had me stumped for a little while how it would be used untill I figured it out, works but the axles now sticks out from the tire hub by 1L each side. A 4.5 axle with stop would be perfect. Have plenty of 5.5 axles - some might get shorter ! Now to build 5 or 7 more units. Potential MOC

Difficult to attach a 7 x 5 frame to a Z28 turntable and would still same problem of axles only being retained by 12T single bevel gear. Think I have found a solution to prevent axles sliding out of thge differential. By reversing the wheels keeps the same wheelbase. The grey half bush sandwhich between black beam and yellow half beam gives more security. Yellow half bush needed to stop tires rubbing.

Started working on my next project which will require multiple caster paired wheels which are to be all powered and steerable. Developing a steerable powered caster unit that can be use in multiple units. Undecided if differential will be required or direct drive with a straight through axle will be OK. Concerned that if a differential is used the the two axles are only retained by a 12T single bevel gear and that If direct drive is used that the tires may scuff as the caster unit rotates when stationary. Suggestions welcomed. Differential drive. Direct drive Next MOC possible a mobile dockside ship loader, a container straddle carrier or ??

Grey / Red / Black / Silver:- The colour scheme was largly determined by the Yellow 1/4 circle gear racks and availability of other parts to achieve a symetrical design and make the vehicle stand out. Some parts are only available in a limited range of colours, i.e. grey frames, engine blocks, cones etc. I was low on yellow parts and as I had plenty of red parts from a former Lego "Super Car" these were used and in my opinion put to better use ! Wheels: again didn't have enough triangle parts to make all the feet the same colour and hence the alternating black & yellow which had added function of dazzling opponents as the wheels rotate.

Some amazing entries for this contest, it has taken quite a long time to decide my vote. 11: 10 18: 6 9: 4 12: 3 6: 2 16: 1 My top three all really deserve 10 points each. Best of luck to all contestants. Doug72

I wish !

Vote Boydell Stomper the only entry with WACKY WHEELS.

Interesting idea, I have been contemplating building a mobile dockside crane which would have a multi wheel under carriage similar to your HD trailer. I was thinking of using the small 28Z turnatbles for each wheel with steering via worm drive, but a lever & reach rod system looks less complicated. How secure would the axles be in the various connectors under tension ? Each axle in your set up appears to turn a different amount which OK if being used as a trailer, for mobile crane need all wheels to turn together in unison. Several cranes of this type are at work at the Port of Tyne near where I live and also are built in the NE England by Liebherr.

Re STOP sign, I too noticed. Grab the image from your photo of the real bus, and print & paste it onto the Lego part.