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I've been researching electric cars...basically, they all are too expensive or they are modified golf carts that are hard to get licensed...and don't even think about the insurance for them. So, i have come up with a fairly serious idea for an alternative I want you guys to critique...seriously.
I
have been thinking about this for quite some time. This is basically a "trailer" but with a difference. The hitch is designed with a fair amount of side to side stability. The trailer has a small generator and a 14 hp electric motor and a set of batteries. Yes, it is heavy. But, it is geared to provide high torque to it's wheels in speeds around 12 to 35 mph...and it pushes the car that is "towing" it.
It recharges from home outlet at 110 volts...it also will recharge from the small 2-1/2 hp generator on board. I can also have it recharge with solar panels, but takes a lot longer....like a weekend of sunny weather. But, here is what it does.
You have your car...that is conventional - and really a large SUV is not good...but a small SUV, like an S-10 Blazer would be light enough....you hook up the power pack "trailer" and start off ...as soon as you get going and get to 12 mph, the trailer power pack kicks in...and you feel a surge of power...you basically get off the car accelerator, letting your car engine idle and an alternative throttle (hand operated and mounted on the steering wheel) is used...the trailer power accelerates the car...not fast but gradual enough to keep most drivers from cussing you out. And you get up to about 35 mph and cruise on steady electric power. If you tap the brakes the trailer power immediately ceases (just like cruise control) and the car engine is primary. Also you have a "kill" button that will disengage the electric pusher and switch right over to the car engine. If you encounter a hill, you can lightly tap the car accelerator to help get on up...or to take completely over for higher speed situations.
As for the problem of hauling around the heavier trailer...the trailer has a sensor in the hitch that compensates ... triggering the electric motor to power "idle" - that is just enough power, even at higher speeds, to limit the strain of the load on the SUV or car.
The range is about 40 miles before it needs a recharge. Or longer if you leave the small generator on while going around town.
I expect the SUV mileage to more than double in the most effective speed ranges and the cost of the recharge at home to be about 40 cents gallon of fuel equivalent (calculating Kwatts cost/equivalent mileage). overall, the average car, depending on weight...the smaller the car the better...would more than double mileage or even triple. If my calculations and paper ideas are right, this thing could mean tremendous fuel savings for any car...depending also on the driving environment...big hilly terrain or really heavy, slow stop and go traffic would probably not be as good as more moderate, average 20 mph or so
As an added benefit, it would license as a trailer, it would not force you into a tiny, crunch can of a car, it would not increase your regular car insurance since towed vehicles are usually covered in most existing policies, it would allow you to have the full comfort of the car air conditioning and heavier frame protection in case of crash, and the state would be in a hell of a situation to restrict it's use as it does in most all electric cars (mainly to protect the road tax they demand from us. They really don't want us to get transportation "fuel" from our home electric outlets that don't have a gas tax meter)
The problems I foresee are that not all driving conditions would be good...it would have some added maintenance…. like you really have to keep it plugged in or the little generator going when not in use (until it is fully recharged), it will drive up already extortion level home electric bills, it will have to have the batteries changed out about every three years...a cost of about $1,500.00 (the batteries are available at Wal-Mart for about $110.00 ea...deep cycle marine batteries)
That's about it...and I'll answer the questions and comments as they come. And, I need you to be practically critical. I am actually going to build one...so your ideas and suggestions will be greatly appreciated)
Interesting newsgroup thread about turning a car into a hybrid.
http://groups.googl...89/f40e23a1025a5354
[Amos Kito, Apr 30 2008]
Hybrid SUV
http://www.chevrolet.com/hybrid/
Grab one off the lot. [Noexit, May 01 2008]
Bionx electric bike motor conversion kits
http://www.greenspe..._motor_bike_kit.htm
Copy this technology. [baconbrain, May 01 2008]
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//$110.00 ea...deep cycle marine batteries// NO!! |
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I am not claiming to be an expert, but there are several better types of batteries available. |
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Litium-ion
lithium polymer
etc |
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Well, I'm glad to hear that my S-10 Blazer is a small SUV. I'll go ahead and get it running again, then. |
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Which brings up the idea that this trailer/pusher would save towing fees. Take it out to where your friend's car is broken down, hook it up and have it shove him home. |
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I'd like to see a safety feature that should be easy to incorporate. Program the wheels to mimic a limited-slip differential. That and an hitch-angle sensor could work with a speed computer to keep the trailer from out-running the vehicle's back end and shoving it sideways. That would help the side-to-side stability. |
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The trailer could be rentable for special occasions. Speaking of rent, it could also be traded in for a charged-up one. Not that that would save on electricity cost, but maybe on time and home wiring. |
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I'm liking this a lot. It's a revolutionary concept. Massive bunnage and best of luck. |
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I was not aware of a hitch sensor. Great idea. Also, I am planning on both trailer tires being driven via independent motors. Power to the motors could be controlled via slip sensors, equalizing the torque in turns and on slippery roads, like wet or icy....although I would hesitate to use this on icy conditions. and the battery selection is based on cost reduction and availability. I am using off the shelf, readily available (already in common use on golf carts, forklifts) parts and am trying to avoid anything exotic. Very simple chain drive, etc. Designing it so the average guy can maintain it...no fancy (and thus expensive) specialty service shops. |
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Also, I had not thought of the emergency use of it...another great idea...and renting them fully charged...there may be a commercial angle there. Thanks! |
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If you use lead-acid, your invention will be slower and less efficient than if you bought litium ion. |
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they are readily available. Google them. |
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BTW, I like this idea. Im not trying to pick at it. |
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And it's even got paragraph breaks ! (+) |
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See...I had no idea the LI batteries were that available. Thanks for the tip..they really would be better, I know the power to weight ration is excellent. Thanks, Much appreciated. BB |
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The biggest thing here is moving the trailer pivot point forward, either literally or virtually. The literal path is taken with anti-dive hitch setups. They have a pivot up a couple of feet and then a spring verticle hinge at the back. You can also do this virtually by using struts or twin hydraulic pistons. |
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Li-Ion is better, more money, more AH per pound, but touchy about recharging, so be careful. |
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Yes, I have used them in electric model aircraft. but with peroper recharging, they may last far longer than lead acid matrix batteries...so the initial cost may be offset by longer life and much better performance. Great help, there. |
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And, I see I will have to bone up my knowledge of hitches and trailer balance. Thanks...BB |
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BB, start crawling on the robotics sites / forums. People sell large used banks of LI batteries with plenty of life left. |
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Look for a electronics surplus site that sells laptop LI batteries. You can have several in series and then connect several series in parallel... this is the most cost effective way to build up a LI bank |
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Fantastic....great help. Doing it. BB |
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so.... you have a trailer to push your SUV around ? |
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anything wrong with putting all the stuff that's in the trailer *into* the SUV ?
specfically the battery pack and the wheel-motors. |
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I like the idea though, ... an electric tractor...err, pusher. |
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Have you considered how much juice is going to be needed to move that heavy thing around, plus the weight of the vehicle? Weight of the batteries + weight of the trailer + weight of the SUV? |
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It also sounds like you've got a fair bit of retooling that's going to be done to the towed vehicle. How do you expect this to be cheaper? |
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It's an interesting idea, but seems like it'd be cheaper just to buy a hybrid. |
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//anything wrong with putting all the stuff that's in the trailer *into* the SUV ? // My sentiments exactly. How would putting the motor on a trailer (other than for the other annotations mentioned) be advantageous? Pushing a car while in gear is bad for the transmission. Letting the car roll in neutral is even worse. |
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//Letting the car roll in neutral is even worse// |
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What? Why? Are you talking about a manual or automatic transmission? |
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A lot of automatic transmissions have a lube pump that is driven by the engine, not the wheels. So shoving the car around means that dry gears are gnashing. Which is why small cars are towed with the front wheels on dollies. |
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It's a real mess, and someone should have designed better. I forgot about it earlier, remembered later, and just now clicked on this to mention it. |
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In addition to the dry gears you will not have complete control of the car if it is coasting in neutral. |
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I saw this as more of an electric assist. Give the car 10HP boost with electrics so the engine just idles at RPM without much load. Like going down a slight hill all the time. You can't shut off the engine for several reasons; vacuum assisted brakes, power steering, AC, etc. It's the reverse of over-powering electric trailer brakes. I've towed trailers where I'd stop faster with the trailer than without. In this you hit the gas, the pusher kicks in and gives you a cheap boost, the engine has it easy and you save gas. I think it would work well. |
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Good points, and back to the original description. I got things off-track by mentioning rescuing broken-down cars. My apologies. |
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There's a BionX battery assist for bicycles that has the programming to help the pedaler a little or a lot, which is probably what this needs to copy. See link. |
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The trailer could also recharge by towing it. 'Though that might be less efficient than an on-board generator, there may be advantages, like regenerative brakes always ready. |
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Just buy a hybrid. Your trailer is only good at harvesting energy but makes lots of waste being carried along all around. |
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BB, Man, you keep saying there is going to be a //on-board generator// |
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You dont need a generator. Your motors can act as generators. The speed contollers available for electric car (for 3-phase AC motors) use the motor to generate power when braking. Regnerative braking. |
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This is, assuming, your NOT suggesting that the power to recharge the batteries come from a gererator operating while the betteries are discharging and powering the SUV. I hope your not.... |
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Generally I like this idea. I see it pushing forwards towards a cheap hybrid conversion of already-existing vehicles in some fashion. |
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This is going to seriously confuse your transmission control module. Some electronic retooling may be required there. It will also put a horrible burden on your torque converter. I think some kind of special mode may need to be built into the driveline altogether. If it could be an add-on and a reflash of the tcm, it might make sense. |
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Given fuel economies in lower gears, you might save more fuel if you reversed it, using the pusher to get moving and the gas engine once you were up to speed. |
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Why are we thinking about this? It adds weight and must be propelled itself, pulled, pushing, whatever. It will be a net user of energy. Any other thought pushes this towards belief in perpetual motion. |
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//It will be a net user of energy. Any other thought pushes this towards belief in perpetual motion.// Not completely true. Yes, this will add weight as any hybrid conversion usually does, and yes it will use energy as pretty much everything does, but the idea is to use less NET energy and this could. |
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I envision this as about a 20HP trailer add-on to a 200HP existing vehicle. Many people bought gas guzzling cars and now find they can’t afford to drive them. So this will work if we can add cheap energy to replace the expensive energy we are now using. So where does that come from? This idea offers three possible solutions: regenerative braking, home power and onboard power. None of these come free so there is a certain amount of gain they will have to provide just to break even, but it is possible. |
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Regenerative braking is a feature that most cars do not have and would be expensive to add-on. If you could siphon off 20HP worth of braking and then apply it to subsequent acceleration, you could have a net gain. Normal brakes just turn this energy into heat, so we are using energy that is normally lost. No free lunch here. |
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Home power is reasonably cheap because it probably uses cheaper fuel (coal, hydro, nuke) that is usually not available to automobiles. If we charge batteries at home and then use that power to assist our normal engine, just take the top 20HP off, we use cheap energy to replace the expensive energy. Cars usually don’t need more than 20HP except when accelerating and when traveling at high speed, so the hope is that, you start your car and have it drive around with little or no load all day. As I said before, imagine driving to work 20 miles slightly downhill all the way and ask yourself if your mileage would improve. |
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Onboard power seems silly, but it doesn’t have to be. We just need to use a system that is more efficient than the present one, so that there is less total fuel used. The first thought that comes to mind is a small 10HP diesel (China makes an air cooled one that is crazy reliable, cheap and loved by home power people) that could be electrically started and run at a constant RPM to recharge the batteries when necessary. Auto motors are inefficient for many reasons; one of the big ones is that they need to be versatile. They need to operate well on a wide RPM range to provide drivability. This leads to compromises that cut power and efficiency like not being able to tune intake manifolds and valve timing. Constant RPM engines can be made much more efficient. Diesels are also more efficient, but most people (especially in US) don’t own them. Also a 10HP engine will produce 10HP more efficiently than a 200HP will. |
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Yeah, it’s easy to tell people to go buy new cars and a store bought hybrid is definitely going to be better than this, but I think this could have a niche market in people who already own vehicles they couldn't give away (I own a Land Rover Discovery with 4.0 that averages 12mpg, so it gathers dust in my garage.) |
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Again, good points, [MisterQED]. Some of the objections to this fail to notice that it is for a niche of sorts. No, it's not for everyone, and no, it isn't perfect. But I'll bet that if [Blisterbob] tools up, he could sell all that he could make. |
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//it is for a niche of sorts// If it is a nich Sir [baconbrain], I'm afraid it would be a very miniscule nich. I can not imagine any set-up where dragging a trailer 20 miles to work and back each day could save me gas money. Slightly down hill both ways or not. The extra cost I have seen while towing a trailer has always far excided any savings I have seen claimed or hoped for here. The aerodynamics alone would kill you. Sorry halfbakers, but I have to call this one as DOA. |
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Still, who was it that said a fool is born every minute? You are right [baconbrain] that [Blisterbob] could sell some of them. Anything can be sold if you find the right buyer. Sounds like he could even sell some right here. |
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What great ideas....and criticisms and comments on things I never thought of. Let me clarify a few points. 1) The Generator...this is just an added thought for when you go some place that might not have an electrical resource..like to a theatre far away or perhpes to a camping area....for a hike...who knows. The little gen would just run until the batteries are recharged...and it run at maximum effeciency rpm thus giving the booster extra range when needed. 2) As for the push capability, the engine on the SUV or car would ALWAYS be idling when driving...never off, to give A/C, power steering, power brakes, computer,etc power. The "Pusher" would make it seem you were always going slightly down hill....until overcome by extra load on steep hills where the SUV engine would then be used to help out with all that lugging power. But, even then, the 18 or so HP in the back...is helping, thus reducing the fuel used by the engine. It is a helper, not a prime source of power. The idea being to get maximum help when the SUV engine is sucking the most gas...at lower speeds, in city type driving. |
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Ideally, if you could recharge the batteries with solar or wind or even from a salad oil fueled or natural gas generator you will basically cheat the oil companies and the government out of their extortion fees. |
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3) The point of doing it with a trailer is to avoid the exorbitant taxation and licening fees...trailers are licensed dirt cheap and require no additional insurance. also, you get to use an already paid for vehicle..instead of having to buy a new high priced hybrid...you buy a pusher that required just bare bones equipment AND no extroadinary gvt safety testing and requirements....also the product liability insurance for trailers is no comparison to what manufactureres go through for vehciles. Finally, anyone could build these and market them with all the innovation free enterprise offer....try entering the automotive building market today...I guarantee, no small guy will get two inches before the big boys murder his dream...remember Tucker? |
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It is a HELPER...not a prime mover. And, I have probably been sending folks in a wrong direction by using a 'small" SUV as an example....although it would work with one. As I said in the original text, the smaller, lighter the vehcile being assisted, the better. |
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I like it... a "first step" hybrid that requires no modification to the vehicle (apart from a custom trailer hitch) and can be used on multiple vehicles. |
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Basically you just idle the vehicle engine and use the trailer for accelerations and regenerative braking. |
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For highway runs leave the trailer at home (unless you're transporting something heavy) |
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Oh, how I love that this trailer can maximize regenerative braking 100% but the awful truth is that it can't even maximize its own inertia to be stored as potential energy. Remember, electric generators awfully lagged behind hydraulic generators in regeneration. People should think how awful is the rolling resistance of the tires you need to compensate, notwithstanding the air resistance due to turbulence created by the SUV. And, due to safety concerns, I cannot even suggest a device to lift the rear tires of the SUV upon braking to maximize regeneration. So, therefore, a useless trailer becomes a hazard to safety and performance. You better buy an enhancement kit/retrofit offered by Alpha–Core/Poulsen Hybrid of Connecticut, USA. |
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[rotary] you're a jackass, but that poulsen thing looks neat; note that it isn't as flexible as the trailer, though it takes away aerodynamic/rolling-resistance losses for some types of driving. |
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[bb] how about gizmos on the gas and brake pedals (instead of a hand throttle) to control acceleration and regen braking |
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And if you play with the fanbelt, you might be able to get power brakes/steering/etc by using the starter-motor (or better still a drop-in replacement for starter and alternator) as a source, fed by the trailer... then you can have short runs as a total electric vehicle, don't even have to turn over the IC engine. |
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I confess I am out of my element, but I am moved to observe; if the naysayers here are correct, then hybrid autos would sit and rust, would they not? Alas, they move. |
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Blistered Bob, you are on the tail of something here. Good luck in your pursuit. |
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//if the naysayers here are correct, then hybrid autos would sit and rust, would they not// Yes [borisbarp], you are most definitely out of your element. The reason that a hybrid can work while this thing will not, is that a hybrid is a hybrid. This is a train. A separate stand-alone gas powered vehicle is either pulling or being pushed by a separate stand-alone electric vehicle. That is two complete and separate vehicles, doing the job of one. While with a hybrid you have only one doing the job of one. |
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No, wait, what am I thinking. It would be worth it just to watch. Can we say - Funniest Home Videos? By the way, any of you ever try to back up a vehicle that had a trailer attached? Does the term "jackknife" come to mind? But never mind that. If it is a good idea, then let’s really go for it. I say you should have another pusher for the first pusher. That would give you even more savings. In fact, if you're right you should be able to string enough of them together, so that you will be able to get where you’re going at no cost at all! |
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Here is one who is out of his element too: the one who commented this: // note that it isn't as flexible as the trailer // |
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How dare he said so... maybe *out of his scientific mind* too. |
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[rotary] I'm surprised at you. Less or not, any flex at all and this thing has negative stability. I suppose it would be no problem if you only plan to use it for a few feet. |
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I dunno, [Ozone]. I've braked a vehicle while pulling a brake-less trailer, many a time and oft. Yeah, a very heavy trailer will chase you off the highway, but a medium trailer with no brakes isn't a disaster. This pusher may have to be limited in its push, as is planned, but it isn't an accident in progress. |
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My earlier suggestion included sensors to detect if things are folding up, and a cut-off switch. Hell, it could even include differential braking to pull things back into line, if everything goes loopy. |
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I'm saying your concerns are a factor that must be taken into account, but not an insurmountable obstacle. |
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I will point out that if this pusher starts bouncing from side to side while pushing, things could get ugly, really fast. Sensors and switches will be needed, but not hard to implement. |
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Oh, [Ozone]. I pretty get into the mind of [FlyingToaster] before commenting such. Of what I understand, he meant *flexible* as "able to adapt to new situation". Notice his statement: //For highway runs leave the trailer at home (unless you're transporting something heavy)// (he is implying that Poulsen Hybrid is too rigid to be detachable) |
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His above conclusive statement out of his honest observation is contrary to the situation. If that trailer is flexible enough, it should not be left home for highway runs. |
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I don't believe the net would be a gain to fuel economy or power especially if your area includes any inclines even with regenerative braking. Fuel economy requires efficiency in three areas: Air resistance, Rolling Resistance and Weight. If you are not improving any of these and making at least two worse then we cannot expect a substantial improvement in economy. |
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{Ozone} Thank you for your note, but as indicated, your opinion is one that already seems questionable to me, therefore so does your clarification. |
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OK folks. For those of you that do not understand what the stability problem is. First off, [baconbrain], it is not a problem when braking. It is a problem while the trailer is pushing. Now, lets exercise our gray matter. I’ll try to explain it so even an IU grad can understand. Pushing is sort of like balancing a yardstick on the end of your finger. It is unstable, but not impossible to handle if you have a small amount of skill. However, unless I am reading the description wrong, the trailer/vehicle connection is not rigid. It is a //hitch//. Now think about balancing the yardstick if the center is no longer rigid, but only HITCHED. As soon as the connection starts to rotate, hang it up. |
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Honey, don't yank my panty off, don't poke my nether either. Don't ever trail behind me like dung. Climb onboard - let's be one. |
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//First off, [baconbrain], it is not a problem when braking. It is a problem while the trailer is pushing. // |
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Sorry, [Ozone], I wasn't clear. My mention of braking a vehicle while towing a brakeless trailer was meant to illustrate a common case where the trailer IS pushing the vehicle. A trailer without brakes is PUSHING the tow vehicle whenever the driver lets up on the gas or hits the brakes. |
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I've been pushed by an overloaded trailer more times than I should admit, going downhill or trying to stop--I lived through it, obviously, and cannot recall feeling a loss of steering control, just a wish for more brakes. Any driver who has ever pulled a trailer has at some time been pushed by the trailer, unless the trailer brakes were way out of adjustment. |
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//As soon as the connection starts to rotate, hang it up.// |
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Exactly! As soon as the hitch-angle safety sensors detect that rotation is beyond parameters, shut it down. Cut off power to the pusher's wheels, and initiate differential braking to straighten it all back out. Or, kick in the clamps or safety struts that keep the hitch from rotating. |
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But, again, that's safety for odd situations--normally, the pusher isn't any more of a problem than a brakeless trailer on a downgrade. |
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Try this, then. Load up a trailer with, say, batteries, but don't connect the brakes if it has any, tow it up to 65 mph and let off the gas. The vehicle will not slow down as fast as it normally does, but it will not go squirreling off into the ditch like [rotary]'s mind. The trailer will push the vehicle for a bit. Now, hook the load of batteries up to wheel motors, install controls and safeties, and [Blisterbob]'s your uncle. |
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i'm not really up on this stuff as much as I should be... how much does, say, 1kwh of batteries or supercaps cost and weigh ? |
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[baconbrain] I give up. If you are going to go to the trouble of creating a stability augmentation system, in the aerospace biz we call that flying by wire, you must have so much money to throw at [Blisterbob]'s half baked idea that no amount of reality will slow either of you down. |
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I just ask you for one thing. Please let me know when and where the first test run is going to happen. I still want to send a tape of it into Funniest Home Videos. |
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Keep at it Bob. They may be right, and maybe it'll be too hard to control, but the only way to be sure is to try. |
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There are a lot of skilled naysayers on HB. I've been warned that ideas involving glow in the dark material will cause radiation sickness, informed that anything involving solar panels is perpetual motion, moving parts equals death, devices that measure ambient microwave radiation will cook anyone in the area, and apparently using a decoy requires you to purchase a thousand decoys before it is ever effective... |
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so to push your car with a pusher that might use solar power obviously means... I'd better not explain what it means, sarcasm doesn't translate over internet around here. |
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HB gets a lot of enthusiastic morons onboard, and the old timers feel the need to beat them down before they go off and create a rocket-powered hydrogen-filled blimp or something. |
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Anyone doubting that a trailer can be used to propel a car should cringe in terror as they read about the EV pusher, which has already been linked to by Flying Toaster. Be sure to film that in operation for america's funniest home videos. The nature of that trailer probably will make it more suitable for nomination anyway. |
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Anyone doubting that electric power from a wall socket can be used to push a car should go back into their caves, and use the internet to join the Flat Earth society. |
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I do think that the existing diesel propulsion for an electric vehicle on freeway trips is a little less complicated than your plan will be. Electric cars will be easier to incorporate electronic controls into, and freeway driving requires fewer turns, and therefore less precision on turning equippment. Your car is a gasoline vehicle, and propelling it with electric will require more hard-to-incorporate controls and steering equippment. |
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I do think that the regenerative breaking rewards from this vehicle will be smaller than you assume. |
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I do think that aerodynamics, and weight issues could kill this idea. |
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I also think it will be you, and not me that will be footing the research and design costs, and reaping any potential rewards. You are taking real risks in designing such a vehicle, but I suspect they will pay off, if not because your invention actually works, then because I know for a fact there are enough people out there willing to buy something like this without ever calculating their mileage to see if it is helping or not. |
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[yrx] saw another one on the net, too... a 924 Porsche being pushed by half a Beetle (why do people always use VW's for these things); very long arm on the trailer, but the guy drove it halfway 'cross the continent. |
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Everytime I visit this site I update my plans for world domination. |
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The solution to the trailering and aerodymanics issues are simple, move the trailer tires right behind the regular rear tires and eliminate the turning flex of the hitch. Since the trailer lacks correct Ackerman adjustment, so it will attempt to make the car understeer. This can be limited by using high profile bias-ply tires on the trailer. Their sidewall flex will allow the tires to just track the slight angles necessary for the turn. This also fixes the aerodynamics issues, because the trailer can just be blended right onto the car and actually improve aerodynamics. |
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I don't think Ackerman-whatsis is gonna make up for that completely, but if your rear tires are close to the bumper you shouldn't need too much clearance... just make the track a bit thinner than the vehicle to keep aerodynamics. |
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Son: Dad, I made you a trailer. You now can waste your gas and it would save it. |
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Dad: Son, that’s too simple. Make it more elaborate: Put sensors that optimize the controls whenever I wreck them in haste and waste. |
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S: Oh, that’s way too intricate and expensive. I cannot place simple mechanical governors due to considerable distance, and moreover, I have to increase redundancy to safeguard against failures of drive-by-wire systems. Anyway, that’s futuristic, so I’ll try. |
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D: Don’t you forget to place differential active braking system on all wheels, so I may not lose steering control or excessive skidding. Please, be careful to calibrate the trailer’s roll sensor in all conditions so it may not contribute rollover disaster of my SUV in emergency maneuvers. Another thing, place hitch-angle safety sensors and control clamps or safety struts that keep the hitch from rotating. Make sure the controls are impeccable in upgrade and downgrade turns where most trailer-related accidents occur. |
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S: Oh, you made it more complicated, dad. I have to place a CPU too, which has an autopilot mode, to do all that work for you or else you would be overwhelmed. Okay, I have to muster a pack of engineering geeks to make it through. I hope they won’t laugh at my trailer project in the first place, or I have to design a chic paramour area on the trailer to pique their primordial urge to innovate. |
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D: BTW, is your trailer light enough? |
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S: Very light indeed, dad—to silence the naysayers: Shame on them. The trailer has state-of-the-art futuristic batteries that are lightweight, powerful, long-lasting, and…hopefully cheap enough. It has composite monocoque structures, with carbon-fiber, titanium, magnesium, aluminum and steel synergistically layered, reinforcing each other to make the trailer sturdy enough. It has light and intelligent integrated circuits and controls. And… |
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D: Oh no, son. Think it over. Do you mean that it would just readily skid upon regenerative braking due to being very light? I fear your geek buddies would attempt to rip the ABS of my SUV and replace it with… oh, I don’t know if it would be safe enough. The remedy I can think of is to have a stiffer hitch with lifter catch to transfer some weight of my SUV to your trailer—and that’s dangerous! Furthermore, without that kind of modification, your trailer cannot push such SUV effectively without burning its Firestone. |
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S: Oh no, I might have been dreaming of future Mars Colonial SUVs… |
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[FlyingToaster] Ackerman angle is the angle the tires need to turn for a car to make a turn. Inside tires have to turn more than outside tires. Since these trailer tires don't turn, they will need to slip. Radial tires are designed to minimize slip to improve handling. Bias-ply tires don't do as well, so when you make a left turn, your front tires will turn left, but the trailer tires will have to turn slightly right. The combination of high profile and flexible sidewalls will allow the tires to slide around the turn. |
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I think the proponents of this trailer rather than a modified hybrid have the right tools/effort/attitude in a wrong direction. They are attempting the impossible when the right solution is already at hand. Let's go for Poulsen Hybrid. |
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Oh, how foolish it is to talk about bias tire slip when the trailer hasn't even enough traction force to significantly push or pull the SUV. Did anyone propose a very heavy trailer? |
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These are reasons enough why some have silly patents just because they have the nerve to think it first then rush ahead, letting everyone to laugh at it later. |
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For the control aspects: There are some good comments above addressing control problems. First, as I said in the original commentary, the hitch will have limited movement..yes, on tight turns the tires may scuff...very much like rear tires on a semi-tractor and trailer do. Second, the drive wheels would be designed to be as close to the rear of the pushed vehicle as possible. |
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Also, have you ever noticed the helper weight support tires on cement mixers...no swing at all...scuff turns only. Stability no problem. |
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As for the slip sensors, realize this unit will be powered by two drive motors providing power to each wheel independently. The power to each wheel will be controlled via a digital controller that is sensing several factors, including but not limited to torque "request" from the pushed vehicle, road traction, power consumption, dynamic braking "request", etc. anything that can be sensed that is pertinent to the most effecient "push" mode can be sensed and output tweaked accordingly. I progam controllers all the time and believe me, there is no difficulty setting up such sensory input and power output and controlling the motors to a very fine degree. It is just a matter of installing the proper sensors. |
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You guys have given me a good insight as to some of the problems I might encounter. I really appreciate that...will save me time and grief. If and when I get this built, I'll set up a web site for up dates. I'll keep you folks with all the constructive comments informed. |
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And, if it is a waste of time and money as some here have suggested...Well, I'll try to have as much fun as possbile during the process to make the whole thing worth my time and my money. |
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[blisterbob] Good luck. If it works, I'd like to see plans so I can put one on my Land Rover. I think to niche is to make diesel electric, but it all depends on the price/weight of the batteries. |
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If you have problems with tire scrub, I thought of a cool hydraulic steering system for the trailer that works off side forces from the hitch and the need for a reverse sensor. Just allowing the tires to flex seemed easier, but it all depends on your rear overhang limiting how close the axles can be together. |
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If you dislike the instability inherent in the pusher trailer, you can, of course use the old single castering wheel trailer design. It does require two auto mount points.
I recall that one of the electric car guys in CA used to tow a power trailer with a generator for range.
You do have a significant weight addition with lead-acid cells. When we built our series electric in EE class, the 30 cell battery held just over 8MJ about the equivalent of 1/2 gal of gas and weighed around 1500lb. By the way, 1kwh = 3.6MJ, rule of thumb for lead cells 30 Wh/kg.
I would not be surprised if a properly designed trailer could actually improve the aerodynamics of some SUVs. |
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Okay, at least I know now someone openly proposes a very heavy trailer. What would the other benefits are there in a heavy trailer aside from greater traction? I think it's more fun to build a very heavy trailer, [Blisterbob]: It has more challenges and has tackled the greatest issue. Don't waste time on proposals for a lighter trailer unless it holds heavy cargo, mind you. |
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Interesting. I saw a trailer just like this once, that somebody built to use as a pusher for his bicycle. It evidently worked well enough to pursue, since the guy went through three iterations to iron out the kinks (rule #1 - do not attach the trailer to the seat post) |
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I hadn't thought about this in years. I like it though. |
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There's some video to be found on the web of a guy who converted his Farmall Cub to electric by attaching the motor to the PTO and running the power into the drivetrain from that end. It seems to work. |
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I must apologize. I looked up the EV Pusher on the net. I seems they are able to push a vehicle without it going horribly unstable. I am still skeptical. It flew, but we finally had to give up on the flying wing because of stability problems until the capabilities of fly-by-wire caught up with the design. The math still shows that pushing is unstable. I must though, in order to maintain a clear conscience, humbly admit that I’ve learned something here. Four wheels on the ground lessens the instability very significantly |
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I must also however stick with my contention that it is not a viable solution to the problem at hand. Ability to handle the instability without wrecking does not overcome the problem of inefficient design and wasted energy. |
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[Ozone] I can actually think up some neat ways for things to go wrong, involving bad road surfaces: potholes, rocks, ice, rain... the trailer might make a situation worse, but if you could put a steering mechanism onto the trailer's hitch, synched to the vehicle steering it would probably be *more* stable than the vehicle by itself. |
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Any realistic "efficiency" equation should include things like cost and ease of maintenance as well as performance of the entire vehicle-train (with and without trailer) over the entire spectrum of anticipated driving scenarios. |
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[Ozone], bravo for the apology, but it wasn't needed. You were patient, logical, polite and quite possibly right, at all times. |
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The EV Pusher is interesting. |
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This is a good idea for city driving, and after reading all the comments, I think the trick is to use two ball hitches at the rear of the vehicle to allow a vertical pivot, but not a horizontal pivot. Make the driving wheel(s) into casters, or just use one. In very sharp turns it would have the least efficiency, wanting to push the rear of the vehicle around, but in most driving it would be fine. You could even put limit switches on the casters to shut off the motors on a very sharp turn, if necessary. |
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The real trouble as someone mentioned earlier is the transmission. If you had a stickshift vehicle, no problem. If you have an automatic, and most of 'em are, this thing will be working against it in any forward gear. You'd have to disable the TCC (torque converter clutch) or something, because it would think it's going down a hill and engine braking would be working against it. Very interesting concept. |
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Would it be worth looking into a primarily electric-solar car pusher? Power would likely be very limited, but in certain areas with clear weather and daytime driving, the removal, or vast reduction of battery weight might be worthwhile. |
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Would it also be worth looking into the use of a flywheel instead of batteries? That also might cut down on weight, and would greatly simplify the regenerative breaking mechanisms... And yes, cars which store energy via gyroscope have been proven to work without flipping over, or noticeably effecting handling in any way. |
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I see that [FlyingToaster] has already linked the Golf diesel pusher, so that saves me some searching. |
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IMHO brilliant. Charge from home; leave out the onboard generator and use regen braking algorythm; tap into the forward vehicle's computer to derive drive data for the trailer control computer; make the trailer invisible to the user (ie braking and acceleration all happens automatically in response to standard pedal inputs from the cabin) and I'd buy one in a shot. |
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If they were available in a swap'n'go deal from service stations, all the better. But user-owned and home-charged works too. |
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not entirely sure about the making it invisible to the driver; driving characteristics *will* be different. Onboard generator (in one of Bb's annos) is there for camping :D |
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Gentlemen, I have been reading this in August, and there are some aspects of Blisterbob's idea which are similar to an Electric Pusher Unit I will be bringing to manufacture in 2009. I will be placing 700 to 1400 pounds of Golf car batteries in a trailer with an electric series motor of 50 hp. and a popular ev controler. The trailer will be 12 ft. long with an eight ft. body and a four ft. long hitch shaft to minimise jackknifing damage in backing up. It will connect to a standard class II hitch installed on any standard sedan or smaller vehicle, with a standard 2"ball. The trailer will have standard tail lights and connect to the car with a standard four pin trailer light connection. The trailer axel will be a standard chevy S-10 axel and tires, and the electric motor will attach directly to the diferential to drive in a conventional manner, no limited slip please. There will be no side sliding or traction problems. this has been proven by thousands of miles of driving with pusher trailer units pushing ev cars in Oregon, and California. On non slipery pavement. (SeeWWW.mrsharkey.com.) There will be a 15 ft. flexable electric cable connecting to the controler in the pusher and with a mini control console on the other end which will be routed to the driver's area with on/off and power adjust controls and a power in batteries remaining meter (aka gas gage).
It will take five minutes to connect or detach and ten minutes to transfer to another vehicle.
Blisterbob, have you built yours yet? You will notice I am NOT using LI batteries, it is extremely important to have PERFECTLY matched cells if you want to build series strings and parallel several together to build a large voltage and current capacity battery, that is all same manuf. same size, same age, and one bad cell can cause melt down or fire and explosion either during charge or discharge... Not for me new cells are too pricey too. I want the lowest cost, most experienced, (older), proven stable in years of use Technology to push me around town for 100 to 200 miles on a charge. I'll start my gas engine and let it idle in neutral, push me around town or out on the interstate at 70 mph and my car will be using one half gallon per hour or 100 mpg because my electric service at my home sells me energy at $0.40 per equivalent to a gallon of gas. And that is the energy which will be propeling me. Oh sure touching the brake pedal will light up the trailer brake lights and an interconect will "Kill" the electric drive just like cruise control. but just don't use it on "Black ice" or other very slipery pavements and none of the other problems I've been reading are of concern here, ever show up on the highway! So build it or buy mine next year. |
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oh god why. Goldberg traction contraption. |
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so no actual prototype yet. so simple but yet you haven't really REALLY tried it yet? Doesn't sound like the sort of company that is about to take change the world with its invention. furthermore good luck defending any kind of patent. |
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WcW, Perhaps it is the 100,000 miles I've driven pulling trailers and tankers up hill and being pushed back down the by them without ever personally jack-knifing is indicitive of my experience and skill. And my tendency to drive slower on wet or slipery pavement. We aren't building them for NASA, It isn't a 500 hp. rocket engine supported with a large hydrogen baloon 24 inches above the road surface with its only connection a universal joint like a six inch length of radiator hose to the pushed vehicle. It is 2400 lbs. of modern trailer with steel chasis, leaf springs, light truck axle, simple diferential drive from one 50 hp. motor, modern radial tires, eight feet from tires to hitch, 250 lbs of weight pushing down on hitch, 1100 lbs on each tire, and a modern motor controler using pwm to allow smooth power from zero to 70 mph for up to 200 miles. The only time it will push sideways is on very tight turns, the operator/driver should know to reduce power on such tight turns just as they would on any vehicle with rear wheel drive, to prevent oversteer. I've had more instability from a mid size stock trailer with only one horse in it, as the 1600 lb. horse moved around in the trailer the truck would wander off sideways requiring constant correction. Still I stayed in my lane of traffic on the highway from Tampa to Ocala and returning, just "Pay-Attention." Also an important skill of drivers is backing up a trailer and steering it into a desired space. With semi's we typically put the trailer between two other trailers with 24 to 36 inches of clearance (Half that on each side!)and a trailer 48 to 56 feet long and over eight feet wide weighing over 50,000 lbs with no special equipment but a mirror on both sides of the tractor to see one side of the trailer you are backing, usually not both. Oh and the transmission is MANUAL with a clutch, not automatic,because that alone saves 20% in fuel costs. and speaking of fuel costs, I had an AMC Spirit sedan with 232cid 6 cyl, 5 speed manual with clutch, PS,PB, and Air cond. and on the highway it got a solid 35 mpg in 1982 for $7,000 new. |
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If the idea is so clear in your head then
why not put ass and grass together and
build one? I could have it done
yesterday and all you seem to have is
talk. Fact is that towing around that
quantity of redundant hardware is
INEFFICIENT. There are serious
problems with the design both in terms
of safety but also in terms of efficiency.
This isn't a horse trailer and you can
god damn bet that if the control system
failed you would have a nightmare of a
time stopping the vehicle. Make a
prototype and show us the vidie. Stop
armchair quarterbacking if you think
the idea isn't half baked and bake it. |
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[Engineering Manager], how specifically are you controlling "throttle"? I get the mechanical part, but where is the human interface? Are you going to put a second throttle somewhere? Same question for brakes. |
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Also all the stuff you are talking about sounds like fifth wheel applications (horse trailer, semi), have you tested much with a standard hitch? I've personally never seen a standard hitch horse trailer, but I guess it's possible. |
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Is this the sole power source for the vehicle? You say the engine is in neutral, but I doubt 50 HP is going to push both 2400 lbs of trailer AND 3000+ lbs of automobile to 70 MPH. Or is this just an assist where you just have a dash slider that says medium thrust and then you drive around with the 50HP electric pushing you whenever the brakes are not applied? |
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Next how big are the brakes on the trailer? Are only one set of S-10 brakes enough for 2400 lbs of trailer or are you kicking in regenerative brakes? I'm assuming you are using the back axle off an S-10 and that usually has the smaller brakes as most of the weight shifts forward. Or are you converting to big after-market electric trailer brakes? |
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All the pushers in the links are significantly lighter than the cars they are pushing, 3:1 for Sharkey, your setup will be about 3:2 or worse. Does that worry you? It sounds like you have extensive experience with semis who have this weight diff or worse, but they use fifth wheels so are different animals. |
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I'm not against this idea, and BTW welcome to the HalfBakery, but as you can see if you look at my previous annos, the hitch is the thing that always worried me. |
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WcW, I am working on building the prototype at this time, so I'll be sure to let you know when to bring the camera over and take the World's Most Sedate Home Video...
MisterQED, Thanks for the Welcome note.
To answer the several valid questions you have annotated: The human interface with the throttle equivalent for the pusher is a mini console with several switches to push, or flip, main power on/cut off, accilerate, set speed, coast down, resume after stop. They work just like your cruise control.
Power ratings used with electric motors is AVERAGE Hp. not PEAK as is used with gasoline engines. So a 50Hp. Electric is roughly equivalent to a 350Hp. rated Gasoline engine. and typical cruising power is close to 25Hp average on level roads. Note I am designing this for standard sedans, not for "SUVs"
As you say most semis use fifth wheels but my horse and stock trailer is a bumper pull. In horse trailers and RVs a fifth wheel hitch is used to minimise jackknife damage when backing, it puts the trailer up in the rear window where it can be better seen and bends 100 degrees before damage occures.
Concerning braking, there are commertially available automatic trailer brake controlers which use only the electrical signal to the brake lights to apply trailer electric brakes, we will use regenerative braking operated electrically with a similar controller to provide a moderate slowing but most of the brakeing is going to be from the pushed vehicle, with anti lock brakes on the rear wheels for anti side skid stability.
I'm told trailer brakes aren't required for units weighing under 3,000 MGVW. There will be a 15 minute presentation on safe driving with a pusher and a 20 minute presentation on preventive maintence for the battery pack and motor lubrication, as well. we are planning to use the S-10 brakes for parking when unhitched, and for application with a spring in case of break-away from the hitch, as our State mandates. |
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[baconbrain] your idea is good and should work well the way you're planning it. I recommend keeping it simple by skipping regenerative braking and attached generators. Regenerative braking will only add about 5% to your range anyway. Also, one motor and a standard differential seems the simplest. [Engineering Manager]'s idea is even better, as pushing an EV is millions of times better than pushing an ICE Vehicle. Why drag around the ICE when you only need it for long trips, or trips longer than the battery powered pusher trailer can handle.
I envision a future with 100% EV's for the 90+% of the driving that is covered by a 100 mile range built in battery pack, and trailer mounted battery packs that can be rented on an as needed basis from gas stations and exchanged along the way for fully charged packs. I would expect trailer mounted ICE gen-sets to exist in parallel, and could also be rented as needed. The trailer shouldn't need a drive unit as the EV already has that. |
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[EM]'s idea isn't about pushing EVs, but also pushing ICE vehicles. The two ideas only diverge in the fine details. I agree with the rest of your anno, except I'd like to see catenary highways that for a fee, that allow you to recharge your batteries as you drive and extend EV ranges to near infinity. |
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[+] because at the very least, it's an interesting idea that should be considered and either persued or the reasons for rejecting it should be clearly stated. |
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Frankly I'm a little amazed at the bickering and useless posts. |
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The key here is to do some math and figure out how much energy it would add to the SUV and there for how much it would increase your MPG. Then figure out how much weight, and drag, it would contribute. |
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The answer is in the numbers. There must be a few real engineers who read this site? |
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