Ideas for a powered trailer.

[Ryland]

As I was at work today, pulling a flat bed trailer, I got to thinking about what it would take to pull a trailer behind my electric car, my first thought was to plug in to the car and have a powered axle, then I got to thinking about the same idea only behind a gas car, of course at this point the batteries would be best as part of the trailer.
My thoughts for controls are along the same lines as the automatic brakes on some trailers, the hitch of the trailer extends and compresses and operates the brakes, a setup like this would work for throttle as well, only speed controllers can be programmed so instead of relying on mechanical dampening, the dampener and lag can be programmed in to off the shelf speed controllers, so a pull on the hitch will give the power source of the trailer a bit of throttle, a trailer like this could even be towed behind a bicycle if the throttle was sensitive enough, of course the braking is very important and with this type of set up could be easy because of regen braking with added mechanical braking for those times when you need to stop fast.
My first thought for building this is to build it off a golf cart, a two wheeled trailer could use just the rear end of the golf cart, for a bicycle a 4 wheeled trailer would be best because it wouldn't need to have tongue weight if it was set up like a wagon.
Big hold up is speed, my idea with a golf car would have a top speed of 30-40mph, weight should not be an issue because golf carts are designed to haul or people, so 600-800 pounds, plus the weight of the body, roof and the design of a golf cart having a low floor, that low floor being a weak point.
Another reference point is that Commuti-cars use a golf cart rear end and have a curb weight of 1,400 pounds or more plus the weight of cargo and two people, GEM Neighborhood electric vehicles come on a pickup version that can haul over half a ton with a total gross vehicle weight of 3,000 pounds fully loaded with people and cargo, again about 1,500 pounds of that is vehicle, so it seems to me that building a trailer that can power it's self for the most part, or assist at least and haul 1,000 pounds or more should be realistic, giving people with compact cars and light weight vehicles like bicycles, motorcycles and small electric cars a great deal of hauling capacity.

[euromodder]

Pushing from behind, the trailer is going to try and push the lead vehicle sideways unless they are lined up perfectly.

With a wagon set up, you have 2 pivot points to worry about - the hitch and front axle pivot.

[CFECO]

The railroad has been putting engines on the rear of trains, to reduce the amount of slack take-up, but I don't know how they manage the rear of the train being compressed and the front extended, slack wise, while topping hills and such. Trains do not have the steering issues a trailer would, (usually)! The Army Gamma-Goat, had a powered trailer driven by a driveshaft from the main unit.

[Frank Lee]

Originally Posted by euromodder

Pushing from behind, the trailer is going to try and push the lead vehicle sideways unless they are lined up perfectly.

With a wagon set up, you have 2 pivot points to worry about - the hitch and front axle pivot.

I wouldn't think a trailer would get too squirrely unless one was applying lots of torque and/or on a low traction surface.

If the wagon was fwd perhaps it would behave similarly.

[Ryland]

I don't want the trailer to push me, I want it to provide 95% of it's own forward propulsion, so you would feel some of the weight of the trailer behind you all the time but it would feel like a much lighter trailer then it is.
For example, I have a Burly brand bicycle trailer for behind my bicycle, it weights maybe 35-40 pounds, even with my 140 pound room mate in it it's not hard to tow on flat roads, but but that is about as much weight as I like to tow so say I want to haul lumber and tools behind my bike, or the idea of the larger trailer that could haul 1,000 pounds or more would work well for towing behind my civic vx as it's only rated to tow 1,000 pounds and any trailer has a bit of weight to it bringing the cargo weight down to 500 pounds or less.
The only time the trailer should push the lead vehicle is while it's braking, I would want a mechanical brake on the trailer along with the regen braking for this exact reason and with the programming of electric vehicle speed controllers the lag time you can program in should prevent the throttle from ramping up to quickly and running you over or pushing the vehicle side ways.

[silverinsight2]

Originally Posted by euromodder

Pushing from behind, the trailer is going to try and push the lead vehicle sideways unless they are lined up perfectly.

With a wagon set up, you have 2 pivot points to worry about - the hitch and front axle pivot.

This seems to work.



http://www.mrsharkey.com/pusher.htm

and this



http://www.jstraubel.com/EVpusher/EVpusher.htm

[dcb]

yah, two wheel, one pivot point should work fine 99.99% of the time. well 100% of the time if you manage the EV power reserves so it is there also when you need it.

I wouldn't commute with it, but if I were going from city to city to show off my EV it would be about perfect.

You would have to spend a certain amount of time at your destination before it made sense to use it on regular trips, vs a non-electric hiway car that gets better hiway mileage. Do the math.

[Ryland]

Those are nice pusher trailers but they can't be used for hauling anything, I'd like something that would work for hauling 4'x8'sheets of ply wood and lumber, or a half ton of dirt and I don't want to own, license, insure and store a pickup truck.

[dcb]

It is hard to imagine dedicated batteries on the trailer (expense). How often you use it becomes a factor (vs something you put together for a couple Benjamins that you limp around with on occasion).

[Ryland]

How often it gets used depends on how well it works, I tend to barrow a truck once a month or so to haul stuff, a number of my neighbors have talked about buying trucks that would sit most of the time for those odd times that they have to haul stuff as well, so what is the cost of buying a truck? you can get something that is in rough shape for $1,500 and are going to spend alot of time and money keeping it on the road.
For my self I would do this because I already have the set of batteries and a spare commuti-car rear/drive axle that is good for moving 1,800 pounds down the road at 40mph when installed in an electric car and at a higher voltage should be good for 55mph, of course a SepEx motor would work much much better.
So for me it shouldn't cost more then $600 in parts and of course the time taken away from other projects and if I didn't have use of a truck that only costs me putting gas in it when I use it, I would be in a bigger hurry to build this, but I think it's a good solid idea that could work for people who are keeping a pickup truck and spending hundreds a year to license and insure it just so they can haul something heavy every few months, or if you look at why people spend $10,000 on a truck they often say that it is so they only have to own one vehicle even tho they only use it for hauling a few times a year, at that point the fuel savings alone would pay for a trailer like this.

Originally Posted by dcb

It is hard to imagine dedicated batteries on the trailer (expense). How often you use it becomes a factor (vs something you put together for a couple Benjamins that you limp around with on occasion).