Making a trailer

[Night Train]

I found a pair of wheel chair wheels at the scrap yard.

I want to use them to make a 'rat' trailer to follow the Ratrike.

The wheels seem straight, very light and have a quick release axle centre and good 26" x 1.25" tyres.
I was thinking of a bit of old ladder as a chassis and then rig something up with a ball joint as a coupler.

The thing I was thinking about was that the Ratrike very easily lifts its back wheel when stopping suddenly. I was a bit concerned with the impact adding a trailer might have on that.
I would, I guess, aim for a fair amount of nose weight on the hitch to weigh the back wheel down and to keep it there when braking but would there be any benefit in adding trailer brakes?
Not sure how I would add brakes yet but I will think of something using side pull calipers or whatever comes to hand I reckon.

Anything else I need to know about or take into account?

The trailer doesn't have a 'need' yet but that will come when the trailer does.

 

[corshamjim]

My immediate thought is that with 26" wheels, unless you sling the load very low and have a good width between the wheels, the c-of-g is going to be dangerously high. If you look at most 2-wheel trailers for bicycles, they tend to have quite small wheels (usually less than and almost never more than 20").

I recently discovered how easy it is to capsize a trailer. Thankfully the ball-hitch detached and no harm done except a scratch or two to the frame of the trailer. It certainly made me appreciate the design of the hitch to separate safely rather than take me and the bike with it!

For trailer bits and pieces a couple of suppliers I've found useful are:

http://www.rosebikes.co.uk/products/accessoires/transport/trailers/trailers
and
http://www.bikester.co.uk/bicycle-equipment/trailers/trailer-accessories.html

Although I cheated and bought my trailer ready-made!

 

[Night Train]

Cheers, those are interesting links.

I'm trying to do this as a pure rat, nothing bought new, if I can.

I am thinking of using the U shaped bit of the top of an old aluminium step ladder to form a drop axle between the two wheel spindles adn then suspend a ladder frame at the bottom. That would give me maybe 4" or 5" of ground clearence for trailer pitching and still mean a large hold or crate all will be mostly below the axle centreline.

I have a small ball joint that I want to use as a hitch and given there will be no leaning articulation needn't be too great.

 

[Night Train]

I had a little bit of a play today, just a couple of hours either side of dinner. Ill at the moment so I should really at 'complete rest' as the doctor puts it.
He might have a point though as I am sweaty and shattered just doing a little bit.

Anyway, here is what I have done.

The tub is an Ikea crate that has been sitting outside with fire wood in it.
The two rails are aluminium extrusions from a window company that were left as samples at a job some 12 years ago. I hung onto them thinking they would be useful at some point.

The wheels are held on with two little bits of scrap aluminium with a 1/2" hole bored through for the axle and then two 8mm holes for the M8 bolts. The bolts screw into rivet nuts set into the base of the extrusion.

That sets the tub at about 4 1/2" off the ground.

The wheel centres are 3" behind centre to give it a natural nose weight and I will leave it longer then the tub so that a half tub can be added and also I can remove the tub and add a suspended net or other carrying members.

I will need to work out what to use to make the front and rear cross members now. I don't have any more of the extrusion nor do I have aluminium welding facilities here.

Still got to dig out the ball joint for the hitch, though I might look at using a steering colum UJ or make one.

 

[ufkacbln]

THe simplest hitch is that used by the BikeHod, but I don't know if it is patented.

Simply a length of hosepipe secured to the bike and the trailer arm and held in place by a pin

 

[Night Train]

Exellent!
I might have to try that. I still have a load of heater hose ripped out of an MR2 so maybe a bit of that would do.

 

[corshamjim]

That looks like it should be pretty nifty when it's finished. I hope you feel better soon and can carry on in earnest.

 

[Night Train]

I've just had a look around for potential coupling components, aside from a bit of rubber pipe.

Here is the collection.

From the left:
A ball joint broken off a car mirror saved from around 1984, steel in plastic with a 16mm ball.
A 1/2" drive UJ.
The tow hitch off a Ransomes Verge Cutter with a 12mm pin.
A track rod end from a 1979 Series 3 Land Rover.


The mirror ball joint is a little weak, being in plastic, but I could use the ball. The ball could be made of cheesy steel though.
The UJ is a possiblity but it is the smallest and weakest from my tool kit. I don't really want to sacrifice a good one.
The Ransomes hitch has good potential but could do with a weight loss programme.
The track rod end may have too much preload as it is quite stiff. It also lacks angular clearance for trailer pitching.

I am tending towards the Ramsomes tow hitch with a rotating eye on the trailer.

 

[Arch]

The Ransomes hitch has good potential but could do with a weight loss programme.

Heh! Did you ever see the original hitch on Pete Eland's extremely long trailer, in Velo Vision? That was made out of bearings off a tractor of some sort!

http://www.eland.org.uk/trailer3#oldhitch

Scroll through the loads, and you'll see my old trike, and one of my bookcases!

Design looks good, I like the low slung aspect, and the fact that it could adapt to boxes, or a net or something. Big wheels will give a smoother roll just like on a bike I guess.

 

[Night Train]

Heh! Did you ever see the original hitch on Pete Eland's extremely long trailer, in Velo Vision? That was made out of bearings off a tractor of some sort!

Yeah, I have some big pillow block bearings like that, they weight more then the average bike!

I can see where the problem is (aside from the weight). That set up pushes the vertical axis pin a whole wheel diameter behind the wheel axle.

 

[Night Train]

Today was spent making the tow hitch as I needed to know what I was making for the front of the trailer.

The hitch in the Ratrike is written up in the other thread but it looks like this.

The drawbar that it receives needs to be a close fit to reduce slack and play but be able to rotate axially to allow the trailer to Roll. The hitch in the Ratrike allows Yaw and Pitch.

I used a bit of round bar that happened to have a couple of holes in it. I turned one end town to be a loose fit on a bit of gas pipe and the then put a bolt though the hole at that end to stop the pipe falling off. The pipe will be the mounting point to the trailer allowing the round bar to rotate freely.

Here is some video of the movement.


The pipe catches on the bolt every now and again so I needed to improve that. I cut the end off the bar and drilled and tapped it for an M10 bolt and a thick washer to take the load.

I then made a housing that was welded to the gas pipe allowing the draw bar to be fitted to the front of the trailer.

In the background you can see a white board with two triangular reflectors. A legal requirement on car trailers but not sure about bike trailers. I had them so I might as well use them.

To fix the front and rear wooden crossmembers to the aluminium extrusion I cut and shaped some oak and bashed it into the extrusion. It was then secured with a screw.

The crossmembers were then drilled and screwed in to the oak. By luck and a fair bit of planning with good machines in my workshop the frame was square first time.

The hitch was then bolted on the front with a matching backing plate to spread the loads.

That's all for now.
It was hard going doing a small amount at a time with the work spread over three floors of the house and resting lots as much as I could.

I might get to take it out for a test un tomorrow or at the weekend.

 

[Arch]

Wow, looking good!

You've probably thought of it, but if it won't weaken the frame it might be worth cutting some holes/slots in the sides to allow fixing of ratchet straps or bungies for larger loads.

And quality too. There can't be many bike trailers with oak in them!

 

[Night Train]

I had played around with the idea of strap fixings but I am reluctant to do anything too unreversable to the aluminium extrusions as they could have a use elsewhere in the future. The extrusion has a lip on it so it will hold hooks in a way.

Anyway, the big box seemed to defeat the idea of the trailer being compactable with quick release wheels so I had another thought.
In amongst the piles of stuff I have I had kept a roll of black out roller blind material. It is black on one side and peacock blue on the other.

I decided I could make a fabric 'skip' to hang in the trailer frame. Good thing I studied dress making and upholstery and have an industrial Singer sewing machine!

I decided on black on the outside as it made it a little less conspicuous and also made the inside brighter. The base layer is double thickness as the fabric was about 12" short and so rather then adding a small amount I overlapped almost the full length for strength.
The top of the fabric is hemmed and lengths of oak inserted to take the weight. The oak was then screwed to the frame around the inside.

The bottom of the 'skip' was only about 2-3" from the floor, ok for road use but it could be a bit low if on a dirt track so I added some straps to pull the fabric upwards to increase ground clearance.

I then made a cover to keep out the weather but with the blue on the outside for a little colour and to reduce solar gain melting the stash of choclolate biccies essential for any cycle trip.

The internal size is 44" long by 20" wide and 12" deep. The base inside is 24" long by 20" wide.
Externally it is 47" long not including the drawbar and 23" wide to the frame and 30" overall. About the same width as the Ratrike.

All I need to do now is add a rear light mounting point and I am ready to roll.

 

[Arch]

Wow, you're not going to be skimping on the biscuits in that are you!

Looks cool! I like the straps to raise the load bay level, very nifty!

 

[Night Train]

I have added rubber 'O' rings to all the moving parts of the hitch both on the trailer and the Ratrike to ease the sloppiness and add some damping as well as keeping grease and water apart.

I also took the chance to weight them.

The trailer weights in at 16kg with the cover.

The Ratrike weighs in at 26.6kg with the panniers on. The rear wheel carries 10.6kg while each front wheel carries 8kg, obviously without me on board.