Building a pusher trailer

[Crash Machine]

I've spent a few sleepless nights thinking about it. I'm going to build a pusher trailer. I've been towing my extra battery in my trailer. With the custom trailer weighing 23 lbs. itself. Plus the Sampsonite suitcase at 13 lbs. And then add the battery and mounting hardware at 25 lbs. and I'm towing quite a load. The motor handles it beautifully. I pedal alot especially at start. But I cant climb hills or carry much extra. So what I want is a pusher trailer that can carry 70 lbs plus batteries,assist the bike in climbing hills and still be able to maintain my 25 mph top speed. Not much to ask(haha). I think the motor would have to be at least 500 watts, maybe more because of the smaller wheel. I don't care much to increase speed, just to not lose speed up hill with a load. I wonder if I used a non-geared motor could a regen. brake act as a trailer brake and gain back some power? Or would the constant resistance of a non-geared motor be too much? I was considering a single wheel set-up(b.o.b) but tales of high speed instability changed my mind...maybe. I think a two wheel set-up would be more stable with more load carrying capabilities. Plus I have a trailer I can modify. But will a hub motor on only one side be a problem? All my experience in motor vehicles and the few examples I can find on the internet tells me that it shouldn't be. With this I could also hook up to a standard bike and let others feel what it's like to ride electric. Which would make me the pusher of sorts.
Am I being a complete newbie in my way of thinking or is this a real possibility? The trailer will go to the fabrication shop this week and I will probably be in the market for a motor within a week or two after that. I may even get a 30 ah battery. So if anyone has any advice or comments I would greatly appreciate them. Also I will try to provide data on the products I buy. Besides the bike is basically done so I gotta feed the need for E.

 

[grwsaltspring]

Hey Crash;

I have done up a single wheeled version that I'm still tinkering with. Mine mounts to the seat post.

I used the e-bike components that I had on hand from my first build to prove the concept. (C-lyte 406, 36V 10 Ah NiMH, Drain Brain...)

Shifted from a 26" to a 20" wheel blah, blah, blah...

Tony did the trailer fabrication for me. http://www.tonystrailers.com/

I live about 7km from town, (my primary destination) 1000ft up a mountain.

The grade varies, the steepest is about 10% IIRC. There are a few flattish "rest" sections, but only in the second half of the climb.

I haven't tested the weight carrying capabilities of my particular trailer yet, I was thinking it would be good for carrying produce to our Tues market in town and 4-6 bags of groceries home at the end of the day. Say 50 lbs+.

We have narrow roads on island with for the most part, no shoulder, so the narrower profile of the single wheel appealed. I did contemplate a two wheel design that could convert to a Kayak trailer though, perhaps next time.

I haven't tested the speed up or down hill yet (IE with a speedometer) so your comment about high speed instability I can't address, but I didn't notice anything particularly alarming going down. (I've hit 90+ KPH going down some sections, without the trailer, in the past)

One thing that I'm still getting used to is the "motion" of the trailer on the bike. Very much like towing a trailer behind a car, kind of jerky at times.

I think a 36V battery is a bit small for anything more than pedal assist, so when this pack goes I will probably try something bigger.

The thing I love the most about this set up is that it takes about 5 min. tops to convert back to a "normal" bike.

I have yet to do it, but I also have the intention of switching between bikes which will be very easy to do.

A surprising aspect is that people don't notice that the bike is an electric assist until I tell them.

Personally I like the way this project is turning out.

Cheers Greg

 

[billvon]

Am I being a complete newbie in my way of thinking or is this a real possibility?

I have an Ibex-based powered trailer with a Crystalyte 406 sized motor. Works well, chatters a little on bumpy roads. The suspension seems essential.

 

[Rassy]

I think using a trailer is a great solution for an e-bike. There are many threads here where too much load on a bike has broken spokes and rack supports, etc.

Of course a trailer has it's own set of issues. I really like the hitch simplicity of my BOB trailers, but it is true that at speeds over 20 MPH the tail will sometimes wag the dog, especially with heavy and high center of gravity loads.

I have made several two wheel pusher trailers, one for a bike and the others for a trike. They all performed great with no handling problems. All of these trailers had two motors, so I can't respond to handling questions concerning one wheel drive on a two wheel trailer. I know the one wheel pedal drive on my delta trike can be a problem on a grade over 15%, and for a pedal only delta trike I would seek out a two wheel drive if purchasing another one.

Good luck with your project.

 

[Crash Machine]

Here's my donor trailer. It started life as a Schwinn Chariot I think. The frame is steel so it could be more easily welded. Heavy but it wouldn't matter much might help. I want to add a bar outboard of the wheel to position drop outs for the motor. Burley makes a similar set-up on their cargo trailer but it's aluminum I think. Will one controller and throttle control two motors and what about battery drain? Actually it was your trailer(Rassy) that first caught my eye.Thanks alot for the info...

 

[Rassy]

Hi Crash. You can run two brushed motors from one throttle and one controller, but each motor will only see 1/2 the max amps from the controller. I have always used one throttle and two controllers for both brushed and brushless motors. The throttle is just hooked up in parallel to both controllers, i.e., all red wires to red, black to black, etc. The controllers must also be hooked to the same battery pack. I.e., if you use two battery packs, they need to be hooked together in parallel, otherwise your batteries will try to balance using the small throttle wires, and probably other small wires within the controller, etc.

As far as drain on your battery, it's pretty much relative to how much power you are using. Of course your trailer will be heavier with two motors, and your battery must be large enough to provide the amps needed, but one motor trying to push a total of 400 pounds at a given speed with a given pedal input should use about the same amps as two motors trying to do the same job.

 

[Crash Machine]

Ok that's alot for a new guy to handle but I think I can. I was planning on using the 10 Ah batteries for my initial tests. That's probably a little small for two motors? Any suggestions on who's got the easiest motors/controllers to work this kind of modification? Or who could send me a controller wired in such a way? I think I want to do it myself for the experience. Don't mean to bombard you with questions.

 

[spinningmagnets]

Here's an old thread with pics and info of 10 different pusher-trailers.

http://endless-sphere.com/forums/viewtopic.php?f=6&t=9855

 

[Crash Machine]

Thanks alot that helped being able to see what others built. Another sleepless night. I keep ya'll posted.

 

[JEB]

I built a pusher trailer with a one wheel drive using a Ego 2hp~ motor, under full power the trailer would "crab" 10" go cart tires were gone in about 30miles start/stopping in a parking lot.

The same motor to a jack shaft with 2 bmx 18tooth sprockets- driving 2 10" go cart tires, with full suspension, have been running it for over a year with no problems.

 

[gogo]

Here's another:
http://www.svendus.se/goldenmotor/

 

[Crash Machine]

The guy in the link above is exactly what I was thinking. He's only using one hub motor. Of course we don't know what problems he ran into. Maybe a hub motor has different physics? The one wheeled trailer concept is easier. I've still not decided. I really just want help up the hills. Also to think of geared or direct drive. Could a regen. brake act as a trailer brake. My controller has a connector that disables the regen. I wonder if I could rig up a switch to it to engage the regen. on downhills to help brake the motor? First I gotta figure out one wheel or two. First things first.

 

[spinningmagnets]

I read about pusher trailers for a while. I may still make one later, but for now I'm going with a bike hub-motor. I remember having some of the same questions, and what I recall is that having one powered wheel on a 2-wheel trailer is not a problem with the handling. I went as far as buying a 20" BMX from a thrift store for $10 just to get the two wheels.

I do recall reading that over 20-MPH the bike handled very squirrely. I want to be 30-MPH capable, and plan to ride around 25-MPH often. You might scan the pics in this thread for some good materials suggestions.

http://endless-sphere.com/forums/viewtopic.php?f=3&t=12329&start=15

 

[JEB]

I found that having a long tounge (pivot mount to wheel cl) no problem behind a bike, or trike, down hills I tend to go 30+ mph. To short it tended to "wag the dog".

 

[Crash Machine]

Ya, my trailer now I typically reach 30 mph+. It also has a long tongue that connects right by the axle. Never had a problem. Tha's why a bob trailer makes me nervous. Maybe the weight of the motor will help.

 

[Crash Machine]

How about this thing that Louis from Fusin sent me.Available in 48v 350 watt or 500 watt Now that's nice...

 

[monster]

you could put a tonne of solar panels on a trailer. ive seen it somewhere

 

[Crash Machine]

That's what I was thinking. Trying to find out now who makes it and how much. Hard to break through the language barrier. I'd learn Chinese for one of these. Will keep posting.

 

[gogo]

That looks like an inrunner motor with the coils having a direct heat path to the outer casing, making for an easy cooling mod if needed. Did you get a price on this?

 

[Crash Machine]

Not yet. I guess it's still night time over there. I wasn't sure if he was saying he had these or if this was just an example of what other manufacturers produce. He did say this was how the Chinese carry heavy loads. I just wonder what kind of wheels it takes. Max torque 80NM, output rpm 260 was what he stated so maybe he does have them.

 

[spinningmagnets]

That looks like it goes to the the powered wheelbarrows I've seen on the web. try that search term. If you use bigger diameter wheels than a wheelbarrow, upgrade the motor, higher voltage...

 

[Crash Machine]

Louis at Fusin doesn't make these but he said 260 dollars for the motor only. He will contact the maufacturer if needed. Pretty cool since it's not his product. Anyways ordered the Bob Ibex trailer today. Gonna go that route first. The two wheel trailer is still going to the fab. shop sometime soon. That way I got both a light and a heavy trailer. I want to make the Bob a regen./ pusher trailer. If you can't decide do both I suppose.

 

[dogman dan]

That does look cool for a trike, or two wheeled pusher. Or get really fun, and make a two wheeled puller trailer, and use a wacky tiller arangement to steer it. Seems like I've seen that in china, with a two wheeled power unit for farms. It hooks to a wagon for transport, and to a plow for field work.

 

[Crash Machine]

Ordered the Bob Ibex yesterday. Actually it was the mention of a pusher trailer with a reversible wheel is what planted the seed for this. That and I'm surrounded by at least 11% hills in all directions. The Fusin controller has an electric brake function. I'm familiar with the idea having been in the crane business for a while. Sending non-phased or reverse phased electic current should work to brake the motor and in this case regen. I wonder if I used a non-geared motor and used a simple switch to engage and disengage the regen. brake especially downhill for a trailer brake. Possibly simply using the connectors on the controller that enable/disable the regen. down a hill. As long as we're dreamin' Hummmmm.....

 

[grindz145]

It seems like you would need to secure the trailer with a couple of extra posts and turn it into more of a trike type of setup before it would get stable. It seems to me like you will have the old backing-up-a-small-trailer scenario where you would jacknife or get unstable. What is appealing to you about building this up in this way? I mean don't get me wrong, looks dangerous and fun