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

[Andyman]

Originally Posted by garys_1k

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

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.

[pfznik]

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.

[Tango Charlie]

Welcome to Ecomodder, Pfznik! I think you will find most of us here are pretty easy going and tolerant of 'creative thinking'.
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!

[MazdaMatt]

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.

[metromizer]

Originally Posted by pfznik

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....My biggest question is to learn how much power would be needed to move the trailer along at 65-70 mph...

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

[pfznik]

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.

[Tony Raine]

Originally Posted by pfznik

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

[millenniumtree]

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

[Tony Raine]

Originally Posted by millenniumtree

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.

[MazdaMatt]

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.