Posted January 4, 201510 yr Well I thought long and hard what I wanted to build for this, wanted to start something brand new. I decided against something aeronautical as I wanted something purely remote control! I thought about building something odd like a snake ! Then I thought about something like a forklift, but then I remembered how much I loved a Big Trak when I was a kid. So I'm going to build my own lego version of this ... Well sort of. It'll have 6 wheels, be skid steer, it's going to have a tipping bed on the back, not sure on the 4th function yet! Not sure what it'll look like yet either So a quick q for all you PF gurus out there. I've only build the Boss and Volvo with remote PF to date so I'm after some help. Apart from size what's the difference between the motors. And when should I use a clutch gear thing, the White gear ?
January 4, 201510 yr Here's a detailed description of the motors: http://www.philohome.com/motors/motorcomp.htm The ckutch white gear is used where there's a danger of a mechanism breaking bricks, or such.
January 16, 201510 yr Author I'm having a nightmare with my MOC. Can't get it to skid steer so I guess I'm missing something in terms of how they fundamentally work ... I can design a car in the real world, just can't design a skid steer ... But then I'm a body engineer and not a powertrain/chassis one! Not got a lot of love for the model now as it's frustrating me So might abandon it and try something else, but no idea if I'll get it done in time (travelling from work & hopefully moving home) ... And I need to work out what to do instead as I'd like to do something different to the rest and I want the functions to be a big "play" feature ... Sorry but I don't like the idea of brakes and gears being functions (no offence intended to those who've done that) I'll try and post pics of my monster on Sunday night when I'm home.
January 16, 201510 yr As well as to defend parts, the clutch gear is also used for child safety - for example when there is something like a winch, for which the string could easily strangle a child. Off-topic, just mentioning it here because it might be worth something to someone. (Unrelated to the clutch gear, I've also found one of my kids wrapping a 2m string from a non-motorised lego winch around themselves, I now hide away the models with long strings to avoid this). @Seaside, skid steer with 6 wheels is harder than skid steer with 4 wheels imho. You have more tyre scrub to contend with (4 of the 6 wheels have to be dragged sideaways if counter-rotating). But it could be done. It works with Big Trak because the wheels are relatively low-friction, and Big Trak is also better used on low-friction surfaces (deep carpet is bad for Big Trak performance). Boop boop beep. Also Big Trak Is Back http://www.bigtrakxtr.co.uk How have you got it set up? All you need is two motors, one driving the wheels on each side. Which tyres are you using? You do need a strong axle design, the skid steer will tend to pull the wheels off the axles, but you can figure that out once you have the basic drive-steer function worked out. Edited January 16, 201510 yr by andythenorth
January 16, 201510 yr How about building this one: https://www.google.de/search?q=metrac&biw=1192&bih=548&noj=1&source=lnms&tbm=isch&sa=X&ei=Vti4VPq4JIvsO9ORgNAD&ved=0CAgQ_AUoAQ Drive, 2 steering modes, raising/lowering the attachments, +1 rear and front PTO driven by the drive motors. That was my second idea, but I'm going with another one with the boring gearbox function
January 16, 201510 yr As well as to defend parts, the clutch gear is also used for child safety - for example when there is something like a winch, for which the string could easily strangle a child. Although it's true, I'm just trying to imagine a child hanging from the 42009 extended boom... :grin:
January 16, 201510 yr Author I was using the unimog/volvo wheels/tyres. As you say possibly too much grip ! I've tried it on a tiled floor and carpet. Carpet is useless but now its struggling on the tiles too ! Was thinking of building some tractor but it sure what functions 3 & 4 would be! Ps you've got to love big trak (I was born in the 70s)
January 16, 201510 yr Author Couple of quick bits of advice sought Do people use the servo motor in general for steering as it offers return to centre or is there another option ? Secondly if I wanted a function where I used a motor to engage or disengage the sliding gears on a constantly rotating shaft (red slider with red lever into dark grey gear) any advice on this in terms of setup and motor to use ?
January 16, 201510 yr Because of the center to steering-simple and effective, and because of how strong it is. At last, it has very little or no play, so wheels stay straight even on bumps, if geaometry is well done.
January 16, 201510 yr 6 wheels and skid steer don't go very well together. Skid steer requires (not surprising) skidding. The longer the wheelbase, The more sideways motion there needs to be during skidding. To effectively use skid steer you either need low traction (like tracks) or a very short wheel base (like a Bobcat loader). It would be extremely difficult to get a 6 wheel skidder to work.
January 16, 201510 yr Yair @Seasider, you could build something inspired by the Melroe M880 Multi-wheel dozer. 8 wheels, and the unimog wheels would be about the right size... http://forums.dhsdiecast.com/default.aspx?g=posts&t=130232
January 17, 201510 yr Author Going to try a tractor ... I think. Question is where I'll have enough build time! @blakbird, I thought that was the case that the track and wheelbase was becoming too big to overcome the grip
January 30, 201510 yr Author Time for a long overdue update ... Firstly this was the still-born project of the 6 wheel monster So then as of last Sunday I tore it up and started on the TC6 project again with a tractor Firstly getting the engine/drivetrain to work - medium (?) motor linked to the drive and also driving the 4 cylinder engine too Offset steering - using a Servo motor Drive and Steering working so time for a test ! ... and it worked Added the PTO shaft and 3rd motor to engage/disengage the PTO 4th and final motor added to raise and lower the rear hitch So now I'm building a second chassis which will hopefully be more refined than this one to hold it all together nicely, i've already got the battery positioned :) . Then its a case of putting some 'trim' on it in terms of a cab, an engine cover and some arches ... oh and deciding what to use the PTO for ! But the challenge is getting it built in time as I'm off away on business all next week ! But this is one project I'm determined to finish even if i don't make the deadline. So how do I post videos ? They'll be taken using an iphone
January 30, 201510 yr Author Oh I'm using a train/variable controller for the drive and steering and a standard flick controller for the pro on/off and raise/lower
January 30, 201510 yr Too bad you ditched the first big project. What kind of tractor this will be? To post the video, go to YT copy the embed link, and put the link here between (media) yourlink (/media) tags. Just put square brackets instead. Edited January 30, 201510 yr by Milan
January 30, 201510 yr Author It'll be a MOT (my own tractor) not going to make it look like anything in particular. Will be a modern style. But my dad will hate me as it'll most probably have red on it and he used to work for the blue tractor company ! I'm guessing I need to upload the video to YouTube then ? I can't post videos via photo bucket ?
January 30, 201510 yr Well Red and Blue (Case IH and New Holland) are both under the same umbrella company: CNH Industrial.
January 30, 201510 yr Oh, sorry, I was thinking by default that you have youtube video. Yes you can use photobucket as well. Just copy the link (embed link, if I recall correctly) and paste it here.
January 30, 201510 yr Author I was thinking of Massey actually. One of the historical competitors in the uk of Ford tractors ( which as you say became New Holland and then CNH)
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