Bowie69 Posted September 3, 2010 Share Posted September 3, 2010 Charles, As you're running locked axles, when you make the gearbox, would using a worm drive be an option, this would negate the need for a brake, wouldn't it? Just a thought, ready to be shot Quote Link to comment Share on other sites More sharing options...
MECCANO Posted September 4, 2010 Share Posted September 4, 2010 Charles, As you're running locked axles, when you make the gearbox, would using a worm drive be an option, this would negate the need for a brake, wouldn't it? Just a thought, ready to be shot Kyosho recently released a crawler with worm drive axles. Great if your doing rock crawling, but horrendous for general plodding about. Instant braking when ever you lift off http://www.kyosho.com/eng/products/rc/detail.html?product_id=104142 Heres and example fo brushed against brushless on a truck that probably weighs in at 4-5kg And with a crazy battery to suit: Bish i think you will be looking to see what people have used on models running on either Kyosho force axles or tamiya jugganuat/ txt-1, as thats whats normally used of scale models of this size. (Axle width of 30cm) Jamie, the only difference between your scania and this project is the size of tires. Yours are about 80mm and i think bish is looking at around the 200mm. Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted September 5, 2010 Share Posted September 5, 2010 So.... if you make your own 2 speed gear box, make the crawl gear worm drive and the pratting about gear in the normal way? Quote Link to comment Share on other sites More sharing options...
Part1cle Posted October 9, 2010 Share Posted October 9, 2010 Any updates please? Quote Link to comment Share on other sites More sharing options...
bishbosh Posted October 10, 2010 Author Share Posted October 10, 2010 Some progress, but not much. Build thread is here to avoid getting a telling off for being too OT Quote Link to comment Share on other sites More sharing options...
bishbosh Posted June 21, 2011 Author Share Posted June 21, 2011 Decided tableware was the better route to take : Some more progress as I have this week off, wheels moving alone a pace and all beadlock rings made Plenty more to do...... Quote Link to comment Share on other sites More sharing options...
Pete Attryde Posted June 21, 2011 Share Posted June 21, 2011 Some progress, but not much. Build thread is here to avoid getting a telling off for being too OT Didn't know you were over there, will follow the build with interest. Pete Quote Link to comment Share on other sites More sharing options...
simonr Posted June 22, 2011 Share Posted June 22, 2011 The build thread is really impressive Charles - it looks much cooler than I imagined ! I guess it avoids the whole MSA problem! In the thread, you talk about possibly using a pair of drill motors and boxes to power it. My feeling is that they will be fairly underwhelming! They do not like shock loadings and do not last that long mechanically unless they are from expensive drills. In which case you are better off with something else! Do you know how much torque and what max RPM you need? Also, what space do they have to fit in to? Also, what voltage are you intending to run and what is the weight of the vehicle? I have quite a lot of electric motor experience from the past! With a few rough guesses at the weight, I make it at about 10Nm into the diffs and about 2000rpm for 20mph? That's based on the vehicle weighing about 30kg. My Dewalt drill (ignoring transmission losses and roll resistance) with this torque would give a top speed of about 5mph. A good rule of thumb (used in other areas) is that your final drive ratio needs to be the (wheel diameter in inches * 10 * weight in kg) / motor power in Watts : 1 to give a reasonable combination of torque / speed with a single gear. For an off road vehicle, I would suggest multiplying the figure by 2 or more. So in your case, about 6:1 with a 1kw motor. That's based on a PM DC motor, not Series wound or Brushless. Having seen your thread - I have a small urge to build a scale Land Rover rolling chassis with my suspension bits (in miniature) fitted to it! At least I have CAD models of all of it so I could just CNC mill / turn most of the bits and mill a channel chassis out of a solid lump of Ali. Not that I need another project of course! Si Quote Link to comment Share on other sites More sharing options...
Pete Attryde Posted June 22, 2011 Share Posted June 22, 2011 The build thread is really impressive Charles - it looks much cooler than I imagined ! I guess it avoids the whole MSA problem! In the thread, you talk about possibly using a pair of drill motors and boxes to power it. My feeling is that they will be fairly underwhelming! They do not like shock loadings and do not last that long mechanically unless they are from expensive drills. In which case you are better off with something else! Do you know how much torque and what max RPM you need? Also, what space do they have to fit in to? Also, what voltage are you intending to run and what is the weight of the vehicle? I have quite a lot of electric motor experience from the past! With a few rough guesses at the weight, I make it at about 10Nm into the diffs and about 2000rpm for 20mph? That's based on the vehicle weighing about 30kg. My Dewalt drill (ignoring transmission losses and roll resistance) with this torque would give a top speed of about 5mph. A good rule of thumb (used in other areas) is that your final drive ratio needs to be the (wheel diameter in inches * 10 * weight in kg) / motor power in Watts : 1 to give a reasonable combination of torque / speed with a single gear. For an off road vehicle, I would suggest multiplying the figure by 2 or more. So in your case, about 6:1 with a 1kw motor. That's based on a PM DC motor, not Series wound or Brushless. Having seen your thread - I have a small urge to build a scale Land Rover rolling chassis with my suspension bits (in miniature) fitted to it! At least I have CAD models of all of it so I could just CNC mill / turn most of the bits and mill a channel chassis out of a solid lump of Ali. Not that I need another project of course! Si Not the best picture but I have already attempted to re-create X-springs on my 1/10th scale Landrover. Seem to work quite well. Based on Si's post I thought of this motor as it would seem to fit the bill and is not especially expensive Motor and this speed controller Speed Controller Pete. Quote Link to comment Share on other sites More sharing options...
bishbosh Posted June 22, 2011 Author Share Posted June 22, 2011 Do you know how much torque and what max RPM you need? Also, what space do they have to fit in to? Also, what voltage are you intending to run and what is the weight of the vehicle? I have quite a lot of electric motor experience from the past! No idea on all fronts except the space, which i have plenty of looking at the size of the brushless motors used on 1/5 buggy conversions. What is more pressing is the lathe's motor is sounding a bit poorly - I might have got it a bit hot today..... With a few rough guesses at the weight, I make it at about 10Nm into the diffs and about 2000rpm for 20mph? That's based on the vehicle weighing about 30kg. My Dewalt drill (ignoring transmission losses and roll resistance) with this torque would give a top speed of about 5mph. Thanks for that, I'll abandon the drill idea then. A good rule of thumb (used in other areas) is that your final drive ratio needs to be the (wheel diameter in inches * 10 * weight in kg) / motor power in Watts : 1 to give a reasonable combination of torque / speed with a single gear. For an off road vehicle, I would suggest multiplying the figure by 2 or more. So in your case, about 6:1 with a 1kw motor. That's based on a PM DC motor, not Series wound or Brushless. .Good to know - not sure of the weight yet I expect it will be 15 - 20kg all up with 8" diameter tyres. I will certainly be quizing you once I have a better idea of weight etc. Will need some input into gearbox design too.... Having seen your thread - I have a small urge to build a scale Land Rover rolling chassis with my suspension bits (in miniature) fitted to it! At least I have CAD models of all of it so I could just CNC mill / turn most of the bits and mill a channel chassis out of a solid lump of Ali. Not that I need another project of course! Thanks, "just CNC it" cheers - it's taken me all day to make one wheel!!! Git. Quote Link to comment Share on other sites More sharing options...
simonr Posted June 23, 2011 Share Posted June 23, 2011 >Thanks, "just CNC it" cheers - it's taken me all day to make one wheel!!! Git. However, it is much more satisfying, manually turning something - I miss it not a lot Seriously though, if you have something that you need to make several of, mail me a drawing and some lumps of metal and I'll run them for you. Payment in Newcastle Brown Ale is always welcome! The brushless motor looks pretty good - but will need a bit of gearing as you will probably be starting at 8000 rpm or so, no load. I do like Brushless motors for the flexibility & torque. For the gearbox, you could use something like a little ATV winch which has a multi (usually 2 or 3) stage planetary reduction. Something like an X1 might be worth a look. By re-engineering it a bit, you could make a multi speed box in the same way as an auto-box which has planetary sets, each with a braking band to stop or allow the ring gear to rotate, then take the drive into an idler shaft from the planet carriers. I think that could give you something controllable using a servo to directly operate the brake bands and give you gear-change without either crashing gears or need for a clutch. Alternatively, you could get the individual gears water-jet cut? Dave NAS90 would probably assist! Si Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted June 23, 2011 Share Posted June 23, 2011 Bish/Simon, My thought proces got tweaked by some of this, nice to see the buggy coming along Charles For gearboxes, have you thought about battery drill boxes? They are available separately as repair items, and in varying quality, like this: http://www.robotmarketplace.com/store_dewalt_gearboxes.html 2 and 3 speed available at a push of a switch..... or a servo, probably. Quote Link to comment Share on other sites More sharing options...
elbekko Posted June 28, 2011 Share Posted June 28, 2011 On the gearbox front, why not a vario? They should be able to handle 10Nm, and with a bit of fiddling I'm sure you can make it locking. Not sure how easy it'd be to package, but I think they can be made to be pretty small (basically the size of the pulleys used). Quote Link to comment Share on other sites More sharing options...
bishbosh Posted June 28, 2011 Author Share Posted June 28, 2011 On the gearbox front, why not a vario? They should be able to handle 10Nm, and with a bit of fiddling I'm sure you can make it locking. Not sure how easy it'd be to package, but I think they can be made to be pretty small (basically the size of the pulleys used). OK, so to start you need to explain to me what a "Vario" is!!! I have not the first idea! Quote Link to comment Share on other sites More sharing options...
landroversforever Posted June 28, 2011 Share Posted June 28, 2011 Here you are charles: http://en.wikipedia.org/wiki/Continuously_variable_transmission Quote Link to comment Share on other sites More sharing options...
Night Train Posted June 28, 2011 Share Posted June 28, 2011 How about a Sturmey Archer hub gear from an old bike. They come in 3, 4 and 5 speed or newer ones go up to 8 speed. Just pull the insides out and you have a multistage epicyclic gearbox with a simple shifter. This is a 3 speed with drum brake. This is an 8 speed with drum brake. This is a Rohloff 14 speed. All would be more then able to handle the shock and torque loadings. Quote Link to comment Share on other sites More sharing options...
elbekko Posted June 28, 2011 Share Posted June 28, 2011 OK, so to start you need to explain to me what a "Vario" is!!! I have not the first idea! What Ross said. Basically just a belt between two conical pulleys on each end. As these pulleys move apart or together, the transmission ratio changes. It's used on scooters etc, and I believe MAN had a transmission like that too. And something in the back of my head says Audi has something similar too. Quote Link to comment Share on other sites More sharing options...
Night Train Posted June 28, 2011 Share Posted June 28, 2011 If you want constantly variable then you could get a Nuvinci hub gear off a bike, or get Simon to make you one. Quote Link to comment Share on other sites More sharing options...
elbekko Posted June 29, 2011 Share Posted June 29, 2011 That thing took me a while to figure out how it could work, but I think I got it now Very interesting, and definitely seems up to the job. Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted June 29, 2011 Share Posted June 29, 2011 What Ross said. Basically just a belt between two conical pulleys on each end. As these pulleys move apart or together, the transmission ratio changes. It's used on scooters etc, and I believe MAN had a transmission like that too. And something in the back of my head says Audi has something similar too. Not sure about MAN, but DAF certainly did: http://en.wikipedia....wiki/Variomatic Audi definitely did, even used on their A/S8 IIRC http://cars.about.co...oknow/a/CVT.htm The old Rover Metro used one too... people don't like them because there's no gear change jolts Quote Link to comment Share on other sites More sharing options...
elbekko Posted June 29, 2011 Share Posted June 29, 2011 Ah yes, DAF, my bad. Quote Link to comment Share on other sites More sharing options...
landroversforever Posted June 29, 2011 Share Posted June 29, 2011 There was a CVT available in the MG/Rover 200 shape cars . Quote Link to comment Share on other sites More sharing options...
D3DPE Posted June 29, 2011 Share Posted June 29, 2011 and Volvo 340's D Quote Link to comment Share on other sites More sharing options...
disco_al Posted June 29, 2011 Share Posted June 29, 2011 and fiesta's.........but anyway - VERY nice looking bit of kit, well done Quote Link to comment Share on other sites More sharing options...
lil_me Posted June 30, 2011 Share Posted June 30, 2011 Really enjoyed reading these, good luck with the project Quote Link to comment Share on other sites More sharing options...
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