geoffbeaumont Posted June 12, 2014 Share Posted June 12, 2014 Does anyone know a good source of information about available electric motors (decent sized ones) - a catalogue or searchable database that gives torque, dimensions, etc? Quote Link to comment Share on other sites More sharing options...
jbs Posted June 12, 2014 Share Posted June 12, 2014 Machine mart? Quote Link to comment Share on other sites More sharing options...
geoffbeaumont Posted June 12, 2014 Author Share Posted June 12, 2014 Machine mart? Hmm - had a look, but they don't list dimensions or torque for any of their motors. Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted June 12, 2014 Share Posted June 12, 2014 Parvalux in Bournemouth are good guys - I sourced a replacement wire-feed motor for my welder from them and they happily matched the original motor they'd made 30+ years ago. Quote Link to comment Share on other sites More sharing options...
cackshifter Posted June 13, 2014 Share Posted June 13, 2014 Brook-Invensys,Siemens. Torque usually depends on how long you want it for, its not as finite as ic engines. .Motors are ysually rated in continuous power. Quote Link to comment Share on other sites More sharing options...
geoffbeaumont Posted June 18, 2014 Author Share Posted June 18, 2014 Parvalux have plenty of info, but looks like all the motors they do are a bit small for what I have in mind. Brook Crompton on the other hand definitely have some fairly substantial beasts! What I'm looking at are automotive traction motors (for an entirely vaporous project which is unlikely to be appearing in the builds forum anytime soon - but as the vapour shed is now designed and has planning consent I can't do much on that until I can afford to solidify it). Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted June 19, 2014 Share Posted June 19, 2014 Do Eaton do motors? They seem to do a bit of everything. Quote Link to comment Share on other sites More sharing options...
ex_mod_90 Posted June 20, 2014 Share Posted June 20, 2014 What sort of torque and speed are you looking at? If you can give me a range, I can point you in the right direction. Are you looking at direct drive or through a gearunit? In my day to day job I cover most things from 120W to 10MW.......Rich Quote Link to comment Share on other sites More sharing options...
geoffbeaumont Posted June 24, 2014 Author Share Posted June 24, 2014 Well, the idea I'm toying with is converting a P38 to electric propulsion*. My initially idea, which I was fairly certain wouldn't work out but figured I'd investigate before writing it off, was to mount two electric motors in the diff housing of each axle, with direct drive to each wheel. Chances of finding suitable size and shape motors with adequate torque? Pretty much nil I suspect! Cooling would also likely be an issue. A more realistic option seems to be two motors mounted in the transmission tunnel driving the existing diffs via prop shafts (independent drive to each axle but not wheel). Finding motors of suitable size and output shouldn't be a problem, but getting the gearing right might be, at which point I'd be back to the tried and tested formula of one motor driving via a locked gearbox. Which is a bit boring, to be honest And reintroduces a load of weight and transmission loss (maybe not that much weight, depending how much lighter one big motor would be than two smaller ones). As far as total power and torque required, the BMW M51 in the diesel P38 has 141hp / 105kW and 210lb/ft / 280Nm - that would be acceptable, especially as the torque curve for an electric motor is much better than the M51 so it would address the diesels main shortcoming (massive turbo lag from stanging). The 4.6RV8 has 225hp / 168kW and 280lb/ft / 380Nm, which would obviously be nicer! From what I've read about electric conversions so far, the very different delivery of electric and internal combustion engines makes direct comparison of either torque or power difficult, but so far I've not really seen anything that provides much help with working out what you'll actually need to shift a given vehicle. I guess this may come down to working it out from basic physics... I've also read that multi-motor DIY conversions haven't generally been very successful, but haven't so far been able to find out anything about why they weren't. So I've no idea whether they problems others have encountered are ones I could realistically hope to solve. I guess I'd be looking at high voltage 3 phase AC for adequate control and sensible regenerative braking. * - yes, I'm well aware this is basically a dumb idea. Rule 1 when selecting a vehicle to convert to electric - pick something light. Rule 2 - pick something with minimal body electrics. Err...at least rule 3 is okay - plenty of room for batteries! Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted June 24, 2014 Share Posted June 24, 2014 * - yes, I'm well aware this is basically a dumb idea. Rule 1 when selecting a vehicle to convert to electric - pick something light. Rule 2 - pick something with minimal body electrics. Err...at least rule 3 is okay - plenty of room for batteries! I'm not so sure about that, if you've gotta lug around half a ton (or more?) of batteries you may as well pick a vehicle with the space & load-carrying. Quote Link to comment Share on other sites More sharing options...
geoffbeaumont Posted June 24, 2014 Author Share Posted June 24, 2014 Well, big and light would obviously be ideal! I guess part of the issue is also cost - a P38 may have room for plenty of batteries, but it's also going to *need* them if you want to get more than a few miles... 1 Quote Link to comment Share on other sites More sharing options...
geoffbeaumont Posted March 14, 2016 Author Share Posted March 14, 2016 I'm not sure what you call the resurrection of an old vapour thread...a haunting? Can anyone tell me the dimensions of a landrover axle differential (P38 ideally, but anything will do for a rough idea)? Quote Link to comment Share on other sites More sharing options...
David Sparkes Posted March 14, 2016 Share Posted March 14, 2016 Can anyone tell me the dimensions of a landrover axle differential (P38 ideally, but anything will do for a rough idea)? Do you mean the overall dimensions of the gears inside the casing, basically what you would exchange with Ashcrofts when the 2 pinion diff shears its pin? (I am including the crown wheel and pinion in this overall package.) Or do you mean the casing the exchange item bolts into, and as though you have cut the tubes from the casing? Regards Quote Link to comment Share on other sites More sharing options...
geoffbeaumont Posted March 14, 2016 Author Share Posted March 14, 2016 Overall dimensions of the actual diff assembly (or I guess more pertinently the inside dimensions of the casing) - trying to work out what could be fitted inside a standard diff casing. Quote Link to comment Share on other sites More sharing options...
David Sparkes Posted March 14, 2016 Share Posted March 14, 2016 ... (or I guess more pertinently the inside dimensions of the casing) - trying to work out what could be fitted inside a standard diff casing. That was an interpretation I hadn't thought of. I don't have an open axle / diff to hand, I was just seeking clarification, so I'll leave the field open to others :-) Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted March 14, 2016 Share Posted March 14, 2016 I have a bare diff casing here.... Will pull it out later, remind me if I forget! Quote Link to comment Share on other sites More sharing options...
geoffbeaumont Posted March 14, 2016 Author Share Posted March 14, 2016 Cheers - no hurry, this is a purely paper exercise at the moment (though if it looks like it has legs then maybe...). Quote Link to comment Share on other sites More sharing options...
simonr Posted March 14, 2016 Share Posted March 14, 2016 You won't find a motor with anywhere near enough torque to direct drive! Even the best hub motors designed for the job will only allow a 2 ton car to climb about 20% gradient with one on each wheel! Most motors reach their peak efficiency around 60-80% of max speed - so you want a gear reduction appropriate to give you this at your cruising speed. If you assume you want to climb a 20% slope and you have 650mm rolling diameter wheels, a 2 Ton vehicle will need a torque at the wheels of 1300Nm (or so) or 370Nm into the diff. 1st gear on a P38 is 2.48:1 and the transfer ratio is 1.22:1 giving 3.02:1 overall. Thus driving the gearbox input you need about 100Nm to be able to make a hill start on a 20% slope. To be able to reach 70mph in 4th gear (0.9:1 overall ratio in to the diff), the motor needs to spin up to 2900rpm. So, you need a motor with 3000rpm and 100Nm stall torque as a minimum driving the gearbox or 1000rpm and 1300Nm (/ No driven wheels) driving the wheel. (Note, transmission losses & roll / wind resistance have been ignored!) Si Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted March 14, 2016 Share Posted March 14, 2016 Pfft, then maybe I won't bother Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted March 14, 2016 Share Posted March 14, 2016 Just remembered this: http://hackaday.com/2012/09/16/700-hp-electric-honda-s2000-built-by-high-school-senior/ And these: http://hackaday.com/2015/04/22/earth-day-electric-vehicles/ http://hackaday.com/2015/05/27/hackaday-prize-entry-an-electric-vehicle-from-recycled-parts/ http://hackaday.com/2012/06/26/maker-faire-nc-2012-electrical-vehicles/ ...well, you know how to use a search button for the rest. Quote Link to comment Share on other sites More sharing options...
geoffbeaumont Posted March 14, 2016 Author Share Posted March 14, 2016 If I've done my calculations right, I reckon that a standard P38 (think it was based on a 4.6 V8, but I've very cleverly not noted that...) has 2728Nm/wheel peak torque when in low range first. Given the nature of torque delivery from an electric motor you can probably get away with less than that (or for that matter less then a P38 diesel) and still have decent drivability of-road (that's also ignoring transmission losses - comparatively, you'd gain a bit back there the more you simplify the drive train - but I'm not sure how much so I'm ignoring it). As far as I can see the absolute maximum motor that might potentially fit inside the diff casing driving directly would be ~1000Nm and probably around 5000rpm max (you'd need to get two of them in, so even that is at best going to be tight). Just about enough for on-road drivability if you live in Cambridgeshire... So no, I don't think direct drive will fly (even if I went the lengths of replacing the diff casing with something bigger). Cooling would also be an issue, given that even water cooled motors specify a relatively low ambient air temperature, and you're talking two of them in a very confined space (I don't think leaving the motors open to the air down on the axle of an off road vehicle is remotely sensible, given what they're going to get dunked in). However...what about mounting a pancake motor either side of the diff casing (as in one in front of the axle, the other behind), ideally each driving a single wheel through separate 90o reduction gears? Cooling is still an issue if you're casing them in, but they aren't packed in quite such a tight space. Not sure about clearance in front of the axle (drag link is likely to be an issue) but behind should be okay. Weight could be problematic, though. Not sure what that would all add up to. Quote Link to comment Share on other sites More sharing options...
simonr Posted March 14, 2016 Share Posted March 14, 2016 I have a motor which could be suitable! It's from a Forklift and was originally run on 48V but the windings have insulation rated for up to 150V. I bought it with the intention of building another electric car, but have never found the time - and it's just sat in my back yard ever since! It's a DC motor - so you'd need a controller such as this: http://www.evnetics.com/evnetics-products/soliton-jr/ (other cheaper options are possible) plus 12 car batteries in series. You could make a workable controller just using contactors switching banks of batteries between series & parallel, or by controlling the lower current which flows through the field windings (which is how I'd figured on running it). The motor cost me £50 and is worth that in scrap alone. If you wanted to give it a go - you would be welcome to it. If it doesn't work, weigh it in and get your money back! For everything EV, DIYElectricCar.com is the best Forum. (I'm on there as SimonRafferty) The thread about Forklift motors is here http://www.diyelectriccar.com/forums/showthread.php/using-forklift-motor-and-choosing-good-7598.html The motor I used in my Electric Freelander is a Siemens 70Hp unit capable of delivering 200Nm and 12,000rpm (I was only running it at 1/2 its max 450Nm). I had a fixed 2.5:1 reduction into the rear diff (3.21:1) so 8:1 reduction. It would make a reasonable job of hill starts and had a top speed of at least 70. I think if (when) I built another one, I would use a multi ratio gearbox to give slightly better hill climbing and lower rpm at speed. Si Quote Link to comment Share on other sites More sharing options...
Nigelw Posted March 14, 2016 Share Posted March 14, 2016 What about electric motor through the auto box? Quote Link to comment Share on other sites More sharing options...
geoffbeaumont Posted March 14, 2016 Author Share Posted March 14, 2016 2164 posts! That's quite an epic thread! At the moment I have no vehicle to tinker with and am only just getting to the point of having a usable workshop (with far too much still to sort on the house and garden, so I'm on a short leash...) - hence playing around with ideas instead of getting on and doing something useful! So thanks for the offer, but I'd hang onto your forklift motor for now! Using a single large motor driving the transfer box (or even gearbox) would certainly be a less challenging approach, but using multiple motors has significant attractions - even just per axle gives you a good deal more control, and if you can achieve one motor per wheel then you've got not just full traction control but the ability to get clever and do things like HDC (while using regenerative breaking) and torque vectoring to when cornering. Given a sufficiently sophisticated controller, obviously. Then there's freeing up space in the transmission tunnel that could be filled with batteries. These look rather attractive for a multi-motor setup (absolutely no idea of cost!): http://www.enstroj.si/Electric-products/emrax-motorsgenerators.html A single large motor looks rather easier to source. Did you use DC just because that was what you'd picked up, or was it a deliberate choice over AC? Of course it helps that at the moment it is just a paper exercise - so I can be idealist and not worry about the cost. I suspect quite a few compromises are going to happen if (hopefully when) it ceases to just be an intellectual exercise... Quote Link to comment Share on other sites More sharing options...
simonr Posted March 14, 2016 Share Posted March 14, 2016 My freelander is (was) AC. The forklift motor is obviously DC. I have no particular preference, each has plus & minus points. One option I have considered - and may be viable is to use 3, 4 or 6 large outrunner motors http://alienpowersystem.com/shop/brushless-motors/12090-outrunner-brushless-motor-130kv-15000w/ driving a single central gear to give you the torque. I think this has a chance of providing the torque required to direct drive a wheel. These motors give about 12Nm - but will rev to 10-20,000rpm. Si Quote Link to comment Share on other sites More sharing options...
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