Push-trailer?

[TroyO]

I'm sure someone has covered this ground... what about a single wheel push motor that attaches to the bike kind of like a kiddie trailer? (Except maybe better balanced and stronger anyway...)

Motor, batteries and electronics on trailer.... hand controls remain on the bike. Clip on the trailer, plug in the control harness and off you go. Unplug/unhook and the weight remaining on the bike is minimal.

I have tried searching but haven't come up with much. I may be using the worng terms... push trailer, powered trailer etc. If someone knows of a term I am missing or a has a link to a post where others have tried it please let me know.

I am going to be doing the first one on a tight budget but to offset that I do have some stuff I can leverage.... I have a few large computer UPS's I may be able to salvage batteries from The units are failed but I would hope I can scrounge a few individual batts that still have some go left.
(I have not opened the up yet, but we are talking 3000VA units so I would guess they have some decent SLA's inside.)

I also have a small mill and lathe in my home shop, and a basic mig welder.

I'm thinking brushed (IE cheap) motors.... any suggestions? Would a radiator fan motor from an auto graveyard cut it? I'm a little more tempted to go with something like this... 1/2 HP, 1750 RPM, 24V...
http://www.surpluscenter.com/item.asp?item=10-2543&catname=electric

The drive power would be fed to a wheel kind of like this:
http://www.harborfreight.com/10-inch-pneumatic-tire-with-gold-hub-41475.html

Is the idea at all plausible? The first one at least will be cheap... $150 budget (Which really means $300... LOL, just don't tell my wife. My greatest fear is that when I die she will sell my tools and toys for what I told her I paid for them....

Anyway... any help or guidance appreciated!

 

[amberwolf]

It's certainly possible, there is at least one thread dedicated to just pictures and basic descriptions of various powered trailers, with links to their build threads or websites, etc., where available.

There are probably a few dozen such trailers here on ES, some of which have their own threads, and some are just described or pictured in other threads. One, very recent, is by Kingfish in his Going to California thread, and it's associated trailer thread.

I'm thinking brushed (IE cheap) motors.... any suggestions? Would a radiator fan motor from an auto graveyard cut it? I'm a little more tempted to go with something like this... 1/2 HP, 1750 RPM, 24V...
http://www.surpluscenter.com/item.asp?item=10-2543&catname=electric

The drive power would be fed to a wheel kind of like this:
http://www.harborfreight.com/10-inch-pneumatic-tire-with-gold-hub-41475.html

I don't know that particular wheel or fan motor would work, but I know that you can run a bike on fan motors. Take a look at my DayGlo Avenger thread, and there is a little info about how I did mine, with a couple of 12V axial-flux pancake brushed fan motors, run at 36V, as a friction drive. Would've been a lot better as a chain drive with a lot more reduction, and I still plan on someday revisiting that. There are lots of details about the construction over on my Electricle blog, first link in my sig, if the info in the first page or two of the thread isn't enough (as it changes to a hubmotor later on).

Personally, I'd just use bike parts, or even a bike trailer (I have two that I plan on turning into push trailers, if I ever have time), including using bike wheels, as they are plentiful and easy to fix or replace if needed. And easy to setup for chain drive from a motor.

 

[spinningmagnets]

"Revisiting a Push Trailer"...3 pages of pics and great ideas.
http://endless-sphere.com/forums/viewtopic.php?f=6&t=9855

 

[Rassy]

Like AW says, there's been a number done here on ES. I think I've done 5 different versions myself.

For a two wheel bike I had the best results using a BOB trailer, which hooks up right at the axle on both sides. My attemps to use a short one wheel trailer resulted in an unstable ride. I also had good luck with a two wheel pusher trailer behind a standard bike. I'll go see if I can find the thread spinningmagnets put together for pusher trailers, and post a link here.

Good, I see that link was posted while I was typing this.

 

[bobc]

here's another (mine)
To be frank, I've done it & it works but it's a bit of a pain to use, mostly because the thing bounces on every bump!
http://endless-sphere.com/forums/viewtopic.php?f=3&t=24698

 

[REdiculous]

I've done it as well and I think the BOB type is the way to go. Mine attaches near the seat and handling is definitely a little sketchy at higher speeds...




Despite the handling issues at "high speed" I like this setup anyway. All I added to the bike frame is the dropouts the trailer attaches to and without the trailer the dropouts hold a skateboard quite nicely so it wasn't a totally useless addition.

Oh, you might want to look for a stronger motor..1/2HP aint much, especially if you're lookin' to use SLAs.

 

[TroyO]

Awesome... thanks so much for the links! Now, off to the research.....

It will likely be SLA and a cheap motor for it. 1/2 HP may not cut it huh? My motor selection may have to wait a little bit until I can see what I can scrounge in the way of batteries and how much they weigh.

One step at a time. I will say what I envision is a little different than what i have seen out there... more along the lines of the "Skate scepter" in terms of driving wheel style. http://www.youtube.com/watch?v=gWHUUsMZLf0

It also may go more vertical and less horizontal in layout... I dunno, too many variables at the moment, LOL. As I start gathering my "Junk pile" it tends to flesh itself out better,

 

[buzzfirst]

I don't know if this is appropriate or not but in the used items section there is a guy that has lots and lots of cheap motors and controllers. Thread name escapes me. It says something like big haul. Anyway he may be able to get you on the road. Disclaimer: I don't know him and have not bought or received anything from him, heck I can't even remember the name of the thread. Good Luck and pictures are always good.

 

[buzzfirst]

Score thread listing.

 

[REdiculous]

I will say what I envision is a little different than what i have seen out there... more along the lines of the "Skate scepter" in terms of driving wheel style

It'll still need to be connected to the bike in some way. Either to the seat post like those half-bikes for kids or to the rear axle, either like a bob trailer or like those 2 wheel trailers. Lower is better.

Here's a thread that might interest you. If you did that and put a wheel on it you'd have an electric "Skate scepter". Pretty neat idea and he did mention an RC version in the vid.

One thing I'd worry about with using a weedwhacker is the clutch and the overall strength of the weedwhacker. A friend and I used an old straight shaft weedwhacker as a make-shift boat motor and even with the springs removed there was a lot of slippage so tons of heat....granted, it's easier to move a bike than it is a boat but pushing 200lbs or more up a steep hill could generate a lot of heat in the clutch if it slips too easy.

 

[TroyO]

I meant in general that I was thinking about a single wheel option instead of a dual wheeled trailer, and that I was going to try and keep it short by stacking batteries/motors vertically and latterally (As much as I can, anyway) instead of horizontally. Not high enough to raise the COG too much, but think more a single wheeled box with the wheel towards the front instead of a long trailer with the wheel at the back. That will put the power wheel as close to the rear wheel as possible which I think will help manueverability? It would still be attached as a trailer, probably to the rear wheel dropout (I think I have that term right, LOL... where the rear wheel bolts.) with some fashion of flexible coupling. CoC (Crap-O-Cad) attached.

I just got back in town and pulled apart that UPS..... SCORE! (I Think)

8x 12V, 9AH SLA batteries.... They are listed as "PXL12090" and have "270W 10 Minute rate" on the side.

The battery unit was replaced because the UPS failed it on self test. My guess is that means that one of the batts died and that most likely 6 or 7 of them are still OK. I need to find out how to charge and test them individually to figure it out. I would guess some kind of load resistor and a volt meter would be enough for me to figure out which units weren't up to par. Even if I can only salvage 3 that should be enough to start out with. If I can salvage 6 I think 36v/18AH would be perfect for what I want. I can also try "zapping them" to see if it that wakes any duds up.

The other UPS I had has been in storage forever and has 8x 7AH cells which if they work may be usefull for something. I am kicking myself for tossing an old 2 stroke snowthrower I had that was chain driven... it never started when I needed it but I kept looking at the frame and thinking it would be soooo easy to convert to electric, LOL. Those 7AH ones would probably be great at that!

Anyway, I need to research how to charge and test these batts so I can figure out what I have to work with so I can get an order together for some of that stuff from the Score thread... hard to beat that value! Thanks for the heads up BuzzFirst!

 

[REdiculous]

I understand not wanting a really long trailer but I don't see how scrunching it up like that will really help. The standard bob trailer tracks well and is proven...


My trailer is pretty long, tracks well and I can still do tight circles (at low speed). Where it's hitched (high) makes it sketchy at speed, however, I hope to modify it soon-ish to attach at the axle.

 

[Rassy]

Troy, I know I mentioned it above, but a super short trailer like you show above tends to "wag the dog" more then a longer trailer. Several of us have tried it, and I don't think there are any still being used, except behind a trike. I think what happens is that each time the bike tilts a little from side to side, a natural thing that happens as you pedal, the trailer reacts. Even coasting at speeds over 20 MPH can lead to a bad wag. To prevent the trailer from causing a problem, the frame and hitch need to be solid, and a little more distance is needed between the bike and the trailer wheel. Even a regular BOB trailer will get spooky at higher speeds if it has too much weight too high. A short two wheel trailer does not seem to exhibit these tendancies.

One suggestion, before you go to all the work of motorizing it, build the basic trailer, load it up with weight (batteries), and see how it tows. Have a plan B, and let us know how it works out.

 

[TroyO]

Ohh I'm sure I will run through plans A through at least J before I even start bolting anything together... then go for K-D2 or so by the time I call it good enough, LOL. The physical trailer is in my mind the easy bit... once I have the rest of the system components together I can just weld up something different and snap the system on to it, no big deal. If it's powered and geared close enough to what I want the actual form factor is not hard to change.

One thing I maybe was missing (Well, there are probably lots) but I just noticed it looks like the BOB trailer (Who the heck is BOB anyway?) pivots just aft of the U that connects to the rear wheel. That would help with the turning radius, I suppose. I was visualizing this essentially 3 foot rigid extension behind the rear wheel and wondering how the heck you would turn that thing. The kid (Or dog in my case) trailer I have uses a spring as the attachment and the arm has a wide clearance sweep that wouldn't work for pushing at all.

What I was proposing would move up and down but be rigid left/right. It would always stay in line with the frame as seen from above in other words. It would lean in the turns with you too. I figured no swing = no wag.

Althought my CoC did make me realize I could do essentially what I want (An easy to pop on/off power unit that keeps minimal stuff on the bike) by using the same components mounted to the rear axle so that the weight of the unit itself rests on the rear wheel and uses friction drive. I don't particularly care that it be a trailer as much as that I can in ~1 minute or less and no tools pop it off the bike and leave less than 1 lb behind. Better yet, if I can swap it from one bike (26" wheeled) to another (24" wheeled) in the same time while leaving behind 1 lb or less on either.

Most of what I have seen so far is while it's pretty easy to pull off the batteries (Which admitedly are the bulk of the weight) the motors and drive systems have to be pretty much unclamped each time, or left in place.

Plus, keep in mind... I am reading a TON on the forum still and learning bits and pieces from everything I come across... I may change my mind at any time, LOL.

 

[Rassy]

Sounds like you have plenty of (good?) ideas.

The first two wheel pusher I did for a regular bike actually had a hitch sort of modeled like a kids trailer. A ball joint near the left side of the axle with a piece of rigid angle iron going back to the front left side of the trailer. It worked very good.

Your idea of attaching the one wheel trailer in a rigid line would be interesting. Certainly would eliminate the sway, but may be a problem during lower speed turns. When I was sorting out my sway problems I thought of using a pair of springs, sort of like anti sway bars used on travel trailers, between the bike and trailer. Maybe even a couple of those screen door springs or hatchback lifters, basically anything that would want to keep the trailer straight, but would allow some turning.

Good luck however you do it.

 

[REdiculous]

What I was proposing would move up and down but be rigid left/right.

That won't work. Trust me, I've tried.

The problem is the tire has to stay in-line with the bike so in a turn it has to slide (and bounce) sideways across the ground. No good on the tire and it's very difficult to control, even with an empty trailer.

 

[bobc]

Like the guys above said, you can make it ostensibly rigid but it WILL pivot somewhere by breaking something. If the trailer is strong enough it will break the bike.
I went out a few miles with my trailer last night: the high hitch does mean you can feel the trailer, but only if something is slightly loose, allowing a longitudinal torsional oscillation to build up - last night it was the fastenings of the trailer hitch onto the bike itself.
The "high hitch" thing is interesting. I don't like the BOB hitch because it makes the trailer so short for side 2 side "wagging".(this is just a prejudice from looking at the system, it seems to work just fine for a great many people...) I went for the hitch over the back wheel because it gives extra traction to the trailer wheel but in practise it is subject to longitudinal axis oscillations of the whole trailer/bike/rider system (though these disappear to all intents and purposes when everything is tight). Perhaps the axle height hitch going to one side of the back wheel of the bike would be a more stable arrangement? A very strong hich could be made for the bike using a combination of frame stays and the wheel axle itself.

 

[TopCat]

I have built a few trailers over the past couple of years. I have tried various methods of attachments that'll allow the bike/trailer to tilt etc when cornering.

Here's a few of mine...

The Long Haul/Heavy Load Trailer. - not finished yet.
The wheelchair wheels have brakes - thats what the black wires are. Still needs another couple of cross beams like the one at the rear, plus brakes rigged up.

The Mono Wheel Trailer.
The yellow bungee is just to hold the box lid on.

The Shopping - come Push Trailer. hopfully. Remade it later.

Loaded with an old busted telly going to the dump.

This is the one I use at the moment. Im redoing the hinge attachment for the rear of my mountian bike.

Building this trailer lead me onto building an Ebike I have removed the motor and have it on my Schwinn Spoiler chopper at the moment.

Another one thats not finished yet

As you can see my front gardens full of trailers in various states of build/repair

My Trailer(s) build thread...
http://motorbicycling.com/f9/bosscats-push-trailer-16616.html

When I started building trailers my idea was to make a fishing/touring/camping type trailer. I found a good few while researching. Here are a couple of beauties. Shows you what can be acomplished if put your mind to it.

This ones done by a German guy who use's it for touring...

This site also shows the construction of the folding top trailer... http://www.w44.de/ Use Bablefish webpage translator if you wish to brows the site in english - http://uk.babelfish.yahoo.com/ Its well worth a browse to see the build process and the amount of work the guy put into it.

Another German made camping trailer...

http://www.guelo46.de/00004.html

I think the next step up after bulding something like the ones above would be to add a motor to them, and some kind of solar or wind powered charging system?

Regards
Tom