powered trailer idea (EV pusher trailer to make conventional car a hybrid)
 

I just found an old (2005) thread by MetroMPG about a powered trailer. http://ecomodder.com/forum/showthrea...ailer-201.html
I was wondering if there was any more thought from the ecomodding community of the merit of such an idea. What situation/application would such an idea be ideal? I'm thinking more along the lines of a trailer assist that would be more universal. i.e.: able to be towed by any standard gas guzzler to help efficiency when being towed. How about a small diesel on the trailer running a generator to power electric drive motors. Like a (scaled down) railroad locomotive.

As a matter of fact... I just sold one of the "surplus" golf cart controllers to a guy in Texas who is building an electric pusher for his PT Cruiser. If he builds it, he'll be the first of many people who've wondered about this idea (that I know of).

http://ecomodder.com/imgs/pusher-trailer.jpg

More pics of his progress in the builder's Flickr album: http://www.flickr.com/mbarkley



I'd think the best application for something like this would be for low speed "EV mode" and assist.

design the trailer properly and you could gain a boat tail out of it.. could serve two functions..

I know I saw a EV Volkswagon with a diesel pusher trailer..running biodiesel.. kind of cool for extended range for EV's

Cool. Is he a member? If so, hopefully he'll post a thread!

Do you have a link, etc.?

I have to say that this is one of the coolest concepts I've heard about in a while. It's certainly doable!

I think that's texoma EV if i'm not mistaken; he started a thread about it here on our site. Small World hey, lol.

While a neat idea, any such design should reduce or turn off the trailer power when the vehicle and trailer are not in a straight line. Otherwise the trailer could cause uncontrolable oversteer in a turn. And then you will not be happy.

I think the ideal application for a powered trailer is a sports car with a big engine. The trailer could have some kind of power that is more efficient for low power use such as an electric motor, a small gasoline or diesel engine, a hydraulic accumulator, compressed air engine or a flywheel. I think the hydraulic accumulator might be the best solution. It wouldn't use any power when stopped and it could easily be recharged by turning on the car's engine and driving while setting the trailer to pump oil back into the high pressure tank. It could also recover energy while braking. For even better efficiency, it might be good to use a small engine on the trailer to keep the accumulator charged up. The extra engine could shut off when the accumulator was full. One possible complication is that adding an engine might be considered tampering with the emission control system. It might also be possible to use a collapsible windmill to recharge the accumulator or batteries when the vehicle is parked. The trailer could also have some extra room for luggage to add to the skimpy luggage space in sports cars.

This system would save lots of fuel when driving slowly in heavy traffic if the car's engine could be shut off. It might be necessary to add some way of charging the battery, keeping vacuum in the power brake booster, pumping steering fluid for power steering and pumping transmission fluid in an automatic transmission to protect the bearings.

Here are a couple of articles about using hydraulic accumulators in cars.

http://www.motherearthnews.com/Green...s-Mileage.aspx

http://www.motherearthnews.com/Green...-Gasoline.aspx

I also like the idea of using a solar and battery powered trailer with a bicycle.

AS Andyman has stated a bit, this is a MUCH harder integration in a new car than an older car. In my base model Aspire with no power steering, no ESP, no auto trans, etc. integration is easy because almost nothing it automated. If you want to turn off the engine and use it to power you forward you have to come up with a VERY complicated system integration that my company into the GM Tahoe 2 Mode Hybrid.

In the end, aren't you just adding a ton of more weight and in-stability to try and garner minimal payback. Would the powered wagon be able to push the vehicle? IE, would the friction of the tires (dependant on trailer weight) be enough to push the vehicle forward? Will it "bind up" under a normal trailer ball and hitch interface?

I'm not saying it won't work, but there are some obstacles to overcome depending on the car make and model. Now not shutting of the car would be a different story, much easier that way.

Yeah, jack knifing on snow and ice covered roads would definitely be a concern. But thats what sensors and computers are for.:p
The guy with the EV porsche pushed by the VW Rabbit trailer claimed no oversteer problems even with (if I remember correctly) full push and the tightest turn radius. No snow in CA, though. *sigh*:rolleyes:

Get a vehicle with Trailer Sway Control and you won't have a problem! but you also cannot key off your car... ;)

We were discussing powering the wheels for an offroad trailer. Would take some stress off the tow rig... But we were discussing using the electric motor at slow speeds and the rest of the time let the motor keep its batteries topped up.

I can see that it would have the greatest advantage in town, but why not optimize it for cruising on the highway?
OK. Let me try and put a finer point on the concept I have rolling around in this melon o' mine.:p
Mr. X gets into his Duramax-powered, gas guzzling PU truck and hitches up his humongous horse trailer. He plans to tow this puppy a couple hundred miles, maybe over a thousand. He enters the anticipated mileage into the (user friendly) 'black box' mounted in his PU truck's cab. This computer interface then calculates the optimum way to run the trailer's auxiliary drive unit. As Mr. X tows his trailer down the highway, the auxilliary drive unit powers the trailer and makes it seem as the trailer is not even there, as far as the load the tow vehicle experiences. Maybe on shorter trips the trailer could even push the tow vehicle a bit.
Try not to think in terms of what you or I are capable of as DIY's. There are engineering firms capable of ironing out the details. I know, 'cause I work for one.:)
On a CONCEPTUAL level, what are the issues to answer? Here's one;

That's the million dollar question. Is it worth it?

I agree, but has he simulated a panic accident avoidance manuver? Stomp on the brakes while turning the wheel?
Looking over the website I see no mention of it.
I know that when I tow my utility trailer fully loaded, there is a noticable effect on handling when I brake while making even a gentle turn. It is certainly managable in daytime, at lower speeds, with an alert and rested operator who anticipates the effect. Maybe the porsche is so heavy with all the batteries the weight and inertia of the trailer is insignificant.

Yeah, no pulse and gliding here.:o
Trailer Sway Control, you say? Sounds interesting. Thanks for the tip!

Well heck, if you are going to get engineering firms that can work with OE's to interface with all of that stuff ( I know, 'cause I work for one too ;) )

I could see a benefit of powering a trailer to help haul stuff, this coudl lead to being able to downsize truck engines that haul things which could improve efficiency. If you can drop a truck engine form an 8 to small 6 and tow the same thing because you do not need that low end torque, image the fuel economy savings!

Yeah, one of the features our company has for trucks. We did the Dodge 1500 for 08 with TSC. Very cool feature, but still won't help someone slamming the brakes and ripping the wheel one way on the highway with a fully loaded trailer. Can only do so much to try and beat physics, but for some odd reason physics always wins!!!

Fun to try though ;)

Gee, I hadn't even thought of that angle *slaps forehead*! :rolleyes:
Nice, steensn! I'll call it the 'divide and conquer' benefit.
regarding 'trailer sway control':
It would have to be a very smart trailer, wouldn't it?

It is all done through a module on the truck, not anything on the trailor. They have semi's that will stop a jacknife now, but they have not rolled that technology into a large pickup tuck yet. Probably will become a "must have" for semi's sometime in the future per government regulation, but not yet.

powered trailer
 

I think the idea of a traction power unit in the trailer,providing thrust is kinda scary.I really like the idea for an EV extender as I think ttoyyoda mentioned,and the streamlining concept mentioned by ebacherville.I went to the Solar-500,at Phoenix Int'l Raceway in the early 90s and saw two electric trailers.---------One was Allen Cocconi's,creator of the black-box for the GM Impact,the other was from a Volvo team.Allen drove his electric CRX up from Los Angeles,with a gen -set on the trailer,feeding power forward through an electrical umbilical cord.-------------Neither Allen or Volvo's people seemed to have caught onto the fact that had they streamlined the trailer,they could have probably extended range.I attempted a motorcycle-based,one-wheel trailer for the CRX just to try the streamlining part,but when I tested it,unbeknownst to me,two carburetor vacuum lines were completely burned through.I still got 48-mpg through Texas,New Mexico and Colorado.I'll have to retest to see what it will do with good hoses.

Don't forget that you can design the trailer with 2 recievers and use a single wheel with suspension that swivels. That would eliminate the risk of jacknifing because the trailer simply becomes an extension of the vehicle, which would allow you to theoretically build a removeable boat tail for any vehicle.

That is exactly what I plan to do to the vibe, build it a portable boat tail for better hwy FE.

In case you have not seen this there are about a million pictures of them on this site to give you ideas.
http://www.singlewheel.com/
Funny how everyone had them and now you never see one.

aerohead,
That sounds really cool. Do you have a writeup about it somewhere?

Updated pictures of the electric pusher trailer project:
www.flickr.com/mbarkley

I really like the modular and retro-fit features of the pusher trailer. The downside to just adding an EV trailer to an existing gas powered sedan would be around town driving while towing a trailer... the post office, the mall, Starbucks and strip mall parking lots near downtown aren't very 'trailer-friendly'.

On the other hand, an EV pushed by Diesel powered APU trailer sounds more appealing the more I think about it. If you work 10 miles away, use the EV wo/trailer. If you are going out of town, headed out on a long trip, hitch up the APU trailer of choice, have it push you down the hiway. When you get to your destination, hotel, temp job site, aunt Madilda's, un-hitch the APU trailer, chain it to the nearest lightpole and use EV power locally.

Train locomotives generate electricy via big Diesel engines that drive electric motors to propel the train down the tracks. But the torque loads are huge, transmitting mechanical power alone through gears has huge losses so the generator makes sense in that case. I am not sure how efficient an EV car with a Diesel electric generator trailer would be, by nature is sounds kind of lossy.

Either way, the cool thing with the pusher trailer or generator trailer is you aren't tied down to any one source of propulsion. Mix-n-match your auxillary power unit, you can own several... if Diesel goes out of fashion, switch to a gasoline APU while you are retro-fitting your Diesel APU to run on french fry grease or biomass fuel. Gasoline lines too long? Switch over to a compressed natural gas powered APU (CNG) that you Phill up through your household NG outlet (Google "Phill CNG"). Will some sort of fuel cell technology take over in 3 years? Hydrogen? Build a pusher trailer around that.

That's the train of thought (sorry...:p) I had. What's the diesel/electric locomotive's 'reason for being' ? My guess is torque. It would take a whopper of a torque converter on a diesel engine to move a train! :eek:
I agree, the diesel/electric concept does sound 'lossy' (hey, it's a new word!) But I would like to see some data...

It's also the basic premise of GM's Volt (except gas instead of diesel). You have an electric drive, battery pack and generator that only runs once the batteries drop down to a certain level.

I think the possibility of more train-like transportation is a definite possibility in the future. Imagine taking a modular approach to your standard car. Have a very aerodynamic powered front 'car' towing a single occupant passenger 'car' with a fly-by-wire control scheme. Add passenger 'cars' as you need them, and hook up with others for power-sharing and the aerodynamic benefit. Add a battery car with solar collector for range extending.

going along w/ the idea of being able to reduce load on lg trucks: the trailer could be used to suppliment durring acceleration and big hills. for steady-state, the trailer's motor would shut off. put regenerative braking, and you''ve got a good trailer brake! Most of the power requirments for towing come from acceleration and hill climbing.

If the tow vehicle has an engine that is too big for good fuel economy, then it may still make sense to run a smaller engine on the trailer and turn off the tow vehicle's engine.

If the tow vehicle has an efficient engine, then I would try adding a steam engine to the trailer to use the waste heat from the tow vehicle's exhaust.

Such would be a perfect application for a Stirling Engine:
Stirling engine - Wikipedia, the free encyclopedia

They work well with low temperature differences, so remaining exhaust heat would could be converted to motive force. It would work especially well on long cruises.

You may be right. It depends on economics. I don't know where you can buy either a Stirling engine or a steam engine. I've read that Stirling engines don't have a good power to weight ratio. I need to do research to learn more about them. I've read that the ideal Stirling cycle has four steps: 1) compression at a constant low temperature (radiator temperature) 2) heating to the temperature of a heat source 3) expansion at a constant high temperature (the temperature of a heat source) and 4) cooling to the temperature of the radiator. The strange thing about these engines is that they require the cylinder(s) to conduct heat into and out of the the gas during expansion and compression. This has to be done fairly slowly for good efficiency. I suspect that it would be easier to convert a normal gasoline engine to a steam engine than to convert it to a Stirling cycle engine. That would require a different valve system.

According to what I've read about the BMW Turbosteamer, an engine running on waste heat would make about 15% of the main engine power. A car going 60 MPH probably needs about 20 HP on a level road so the waste heat engine should be large enough to produce about 3 HP. If it were more powerful than that, it could produce more power when climbing hills.

I have been thinking about powered trailers for sometime now so I googled "Powered trailer" and found this site which I think is great. I registered immediately and, while this is my first post, I certainly doubt that it will be my last.

I will be retiring shortly and would like to buy a vintage travel trailer for restoration and to spend two or two or three months a year seeing something of the country. Unfortunately, Pulling a trailer (even a small one) with a pickup or large SUV is in direct conflict with my basic inclination to be as green as possible. Since my home is in the city, the most appropriate vehicle for me would be agile, easy to park and economical. Probably a small hybrid because of their excellent mileage in an urban environment, not something capable of towing 5000-10000 pounds.

With this in view, my ideal powered trailer would never actually push the tow (guide??) vehicle since I believe this would require much more design effort to assure an acceptable level of safety. Rather, the goal would be to supply power to the wheels which wheels to assure that tension in the hitch was always as close to zero as possible and would
never be in compression that would cause the tow vehicle to be pushed. my thinking is that the drive system would consist of internal combustion engine, generator, batterys, and an electric drive motor, possibly one for each wheel. Also required would be a sensor for determining the load in the hitch and lots of supporting electronics. I would like to see the engine/generator as light and small as possible so that it could be moved to an out of the way location when the trailer was in use (parked, not traveling).

My biggest question is to learn how much power would be needed to move the trailer along at 65-70 mph keeping in mind that it will be drafted to some extent by the guide vehicle. I look forward to finding the answer to this and many other questions relating to efficient trailer pulling on this forum.

Welcome to Ecomodder, Pfznik! I think you will find most of us here are pretty easy going and tolerant of 'creative thinking'. :p
Your goals are very close to what I had in mind, as well.
As for determining the load in the hitch, I was thinking of piezoelectric load cells between the ball of the tow vehicle and the tounge of the trailer.
Unfortunately for me, it's just a mental exercise at this point, but I would love to hear your ideas and any experiments you may perform!

For load sensing, couldn't you use the tongue of a brake-assisted trailer? I think they have a piston in them that activates the trailer brakes as the tow vehicle slows. You could use the piston to shut off your pushing motor. This is an interesting concept, I like it.

ah yes, the dream of retirement and seeing the great you-ess-of A :)

I've done a fair amount of trailer towing, a 24ft then later 32ft bumper pull box trailers with a 1 ton Ford dually. What you'll find is the power required (to keep the towing weight neutral) varies quite a bit. Frontal or cross wind or not, uphill grade or downhill, starting from a stop, etc. Constant cruising load varies more than you'd think (when you tow alot, you realize just how non-flat the terrain really is) Just thinking out loud here; A vintage trailer is going to be heavy, you'll need a worthy truck w/brakes to suit and a suitable powerplant, there's no way around that. If you go that route you are saddled with the weight issue. I once saw a 4cylinder Diesel Isuzu delivery truck converted for racecar trailer towing, looked great and got great mpg according to the team.

Another interesting read: Cummins did an areodynamic study on tractor trailers rigs and areo recommendations. It's a powerpoint presentation (slides) that is well worth looking for and reading when you find it.

I bumped into a guy out in Death Valley last fall, who had just retired, and was seeing the country by motorcycle. he wasn't a real motorcycle buff per se, he had dreams and plans, and wasn't about to let fuel prices change that. It turns out he'd been on the road since spring, home is Michigan. He was camping and motel-ing, plus staying with friends and relatives. Sounded like a great retire kick-off trip to me:thumbup:

More on powered trailer
 

I have some further thoughts on the use of a powered trailer as a means of pulling a trailer with a car that would also be practical for everyday use from a green point of view. In the future I will call this the guide vehicle as opposed to tow vehicle. My first concern is to determine why a portion of the weight of all trailers is supported at the hitch. Why not have four wheels out at the corners, wagon style, so that the trailer could stand on its own with out landing gear. After all, small autos brought along behind motorhomes are towed four wheels down. Is there some simple dynamic reason why this is not a good idea (ie, reason manhole covers are round)? Am I missing something? Of course, front wheels (possibly rear as well) would have to pivot or be under a fifth wheel in order to track properly.

My reason for asking this is that by taking the vertical load off the hitch, opens the choice for guide vehicles to even even further (to smaller cars) since concerns added weight and weight distribution no longer exist.

Come to think of it, I guess the next thing would be to eliminate the physical connection between vehicles alltogether and communicate relative positions by radio or light waves. You could then lead your 32' trailer along with a moped. At a camp ground, you could stand by your trailer with electronic gear such as an radio control model enthusiest would use and fine tune your trailers parking.

remember the OLD horse trailers with tires at all 4 corners? the front 2 turned with the hitch. no tongue weight, but having 2 different pivots makes it hard to back up (think of a semi hauling 2 trailers)

but i think it could work with a powered trailer. you could use just trailer power for backing up (have the rear trailer tires be the "powered" axle)

if you had a low speed controller, you could even move it around a little at camp, when detached from the tow rig.



but always remember, the tow rig may have to pull full braking duty if all this electronic stuff failed.......






hey, with all this work, just put a steering wheel and petals on the trailer, and tow your car with it :D

I've considered the idea of a powered trailer for a bicycle as well. It would just be a single-wheel with a small lawnmower or strimmer motor on top. People say you can't use a vertical-shaft motor for these types of things, but I say you just have to be more creative. :P

how about a right-angle drill adapter? you can get some pretty heavy-duty ones.

I wouldn't use a pusher trailer without a direct cable mechanical disabler accessible from my driver's seat. Last thing I need is a stuck throttle when i'm trying to use an offramp.