allanp

That's a shame it didn't work so well. The idea for planetary reduction looks very similar to a JCB i'm working on right now. I have built the axles and they work very well, maybe you could try them. The dark grey axles on the front are supposed to be the new 4 long with stop axle, but I only have the 3 long in MLcad at the moment. P.S. I would love to see another photo behind the wheels of your truck so we could see how you planetary gearing is set up.

Unfortunately no, not for the whole thing anyway. Right now I only have the main mechanism for the rotor cyclic/collective control, which is probably the most interesting part anyway. This was for the technic challenge (it's now one of my subbmissions in the final 20 that can be voted on). Since I only had two weeks to design and build this baby that is as far as I got on the computer before I got impacient and just started building the thing for real. The colour coded arrows are meant to sybolise the functions shown on the main picture and how SOME of the linkages move. It has had some minor alterations since then (for instance, as you can see in the photo, the steering linkages are longer now). If I have time i'll have a go at making the whole thing in MLcad, but that could take me a while. If you want, and also if somebody tells me how, I could send you the MLcad file to this part and you could rebuild it better from that I would think. If you're interested here's the original thread. Perhaps it would be best to revive that one to dicuss this MOC further in order to keep this thread on topic http://www.eurobricks.com/forum/index.php?showtopic=38729&st=0

The flex system is great, i've used it many times in MOCs including this one: This would have been somewhat tricky without the flex cables due to the nature of how the cyclic/collective control works.

I remember learning so much from lego technic. I remember when the science teacher broke out the dacta for quite a number of lessons and feeling quite wierd at already knowing more than he did about mechanics and how various gears, differencial gears, linkages, pneumatics and such all work. To solve mechanical problems (like a working gear box and lifting heavy weights) that he could not was literally childs play to me. I guess that's the difference between knowledge (what memorising a textbook gives you) and true understanding (what playing with technic gives you).

Ok you are almost there, i'm not sure if that red belt will be tight enought but you should be able to solve that, but the main problem I can see is that you don't have the beams on the front of it. Those beams open up the crank pieces, spacing them apart so that they are at the angle shown in my intructions. If you look at step 7 of my instructions, you will see that one crank piece rests on top of the beam, whilst the other rest below the beam. If you don't space them apart like that then the crank pieces will just try to push the gear away instead of rotating it. Bear in mind that this design is straight out of one of my excavators, those beams were prevented from coming off the axles by being part of the surrounding structures. In your last two pictures I see you have the beams, but they are no good sitting on the table . You should also space the two connector pegs holding the beams together as I have spaced them in my instructions as one of them in your picture is currently where the grey, five long axle that the gear is mounted on should go. Hope this helps.

Yes it is a grey t-piece, sorry again about the lame instructions. Mine have always worked, however the black belts won't work as they are not tight enought to properly position the crank piece into the teeth of the gear. You could try doubling the belt up on itself so that the same belt goes round the triangle twice if you don't have any white belts. This might make it tight enought. Trust me tho it does work if you have the right pieces, if not then you can always tweak the design a little to make it work. So far I have not had to do that so I don't know what other tweaks to suggest.

8856 whirlwind rescue also used two flex cables to control the tilting rotor blades. I think there has been more than one plane to use the flex system but I could be wrong. The flex system, specifically the double sided connector, has also been used in various mid scale fl car, like the 8445 (I think that number is right) to control the steering.

Well I wish you the best of luck with it, be sure to keep us posted.

As far as the technic pin connector round with slot goes, I think the slot was added for lower poduction costs. To produce the older version was more expensive because it is two peices glued together. Without even more expensive collapsable molds this was the only way to get a groove inside so that a pin could "lock" into it. The new design however, whilst not looking as good, only requires one mold as it is one piece, the pin can now lock into the slot.

Which particular part do you mean? You have shown 3.

WOW, that is truely awesome, once again! Nice one

The PF motors do work quite well as a dynamo. There is a new PF motor in the renewable energy educational set that is designed specifically to be used as a motor and dynamo.

Well the obvious answer is to just use a standard lego motor in reverse. Any lego motor will act as a dynamo. However if you actually want to build a dynamo then make sure your magnet is spinning in a way that changes the magnetic feild in the coil as it spins, ie don't spin it on the north-south pole axis as the magnetic feild is symetrical about that plane, so the feild won't change as it is rotated. Spin it on an axis that is at 90 degrees to it. Also bear in mind that the magnetic feild quickly gets weaker the further you move away from it, so wrap you coil as tightly about the spinning magnet as possible without it touching. Hope this helps.

Well you could try this switch I designed. Sorry for the lousey instructions, was my first time trying to make instructions. I find this switch works quite well. To operate it, pulse the motor left or right. When you release power from the motor, the motor should self centre but the valve will remain on. This means you don't have to keep the motor stalled to keep the valve on. With some tweaking you can make it proportional, so that when you pulse the motor once, the switch moves a bit, pulse the motor again and it moves a bit more. This is useful to avoid anything that is heavy coming down too fast. It is also easy to return the valve to centre, just pulse the motor back the other way once or twice to turn it off. I hope this helps. This valve is pretty much as it appeared in one of my excavators (x3) and was held together by surrounding structures. Next time i'll show you the compressor I designed for it. That should give you all the power you need for your excavator. Ta ta for now

That's awesome, the suspention is especially cool!

Ah, of course. Silly me. I forgot that the old pumps did not have a check valve like the current ones do.

Ah, longer pneumatic cylinders Sorry, where was I? That LA looks to be a big improvement in terms of performance on the official ones, nice one

Really, I have never noticed any effect like this with pneumatics, and I lift some huge loads with them at times, often more than what LAs can handle. Loading an LA will also increase friction, decreasing efficientcy to the point of stalling a motor or activating the clutch without having transfering much of the motors power into linear power.

I would stick with the pneumatics, I really have no time for LAs, even the new ones. I really need to do a test to see how powerful pneumatics are compared to LAs, pneumatics just seem much more powerful to me but I seem to be in the minority in that respect. Besides even if the pneumatics were weaker i'de still prefer them to LAs in most cases. Correct me if i'm wrong blakbird, but I thought you only really needed the valve block if there is no external force (like the weight of the boom) to retract the cylinder. Besides the original crane only used one port on each cylinder.

I would start again from scratch, but DON'T DITCH THE PNEUMATICS. I have built more than one excavator of a similar size and the pneumatics move at a realistic speed and with plenty enough power to dig a nice hole in my garden. I did try using LAs but, well, it was slow and boring and weak (even with motors directly attached) and too unrealistic for my liking. Anywho, first of all, concentrate on building your compressor. I notice you have one XL motor powering about 8 pumps!!! From those parts you can get all the power you'll ever need. However you should off-set the pumps so that they are not all going in and out at the same time, like the pistons in an engine, they are offset for smoother operation. This will give you a much more constant air flow and make life much much easier for the motor. This method gives me masses of power from even quite low batteries. The biggest one i've built also had 8 pumps powered by one XL motor. it was about 4 studs wide, 9 studs long and about 7 studs high plus the motor, so it should fit in fairly easily, oh and make sure your hoses have no kinks in them. Personally, I don't like powering my switches remotely as I like the precise control of operating the switches manually, however if you must make them RC, I would suggest coming up with a different method of controlling them as the ones that have shown up here around eurobricks draw alot of power just to keep them switched on. This wasted power means there is less power going to your compressor motor. Fear not, there are other ways of controlling your switches remotely, but i'm not gonna take the fun out of the challenge by telling you, . If this model is only for show then you don't need to re-inforce the turn table, just position the motors and batteries inside the superstucture so that it is balanced. However it would be a shame to waste all that power the pneumatics can give you. So if you want to do some actual digging in the garden (which is more fun when the neighbours aren't watching ) then you might want to re-enforce it. four wheels on the underside of the superstucture running on a smooth surface below works quite nicely. The rest is all down to trial and error. But keep at it, trust me, a good pneumatic excavator is well worth the time getting right, it's just so much fun to play with. It's like not playing with a toy at all, more like playing with the real thing, just smaller. How cool it that!

WOW, that's really compact. So many features in such a tiny space, nice one.

I've always loved the atom. For £30,000 you get the performance of a £300,000 car. I agree that it's awesome looks is begging to be realised in technic, here is another try by everyonesgrudge. It even features a push rod actuated gearbox, although it's hard to tell exactly how well it works from the pictures. Full gallery is here: http://www.brickshelf.com/cgi-bin/gallery.cgi?f=428622

Your other designs may have been more appealing to us AFOLs but remember, most of those who will be voting will be kids, who have a different view as to what is cool and what is not. So fear not as hopefully, the designs they have picked for you may have given you a better chance of winning!

Congratulations to everyone who have made it this far. YEEEEEY, my two best made it. Well so did my worst two, they are actually the same two, my only two submissions to the competition! (me being Althetechnicmaniac!). Guess two out of two ain't bad. But very well done to Zblj, 4 entries! Nice one dude, you da man!!!!!!!

I would suggest using a gearbox similar to 8480, using one motor to power the functions and another to switch between the four functions using cams. Here is one from brickshelf built by Hi-Lift that is similar to ones I have built. http://www.brickshelf.com/cgi-bin/gallery.cgi?f=379174