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astronomerroyal 05-30-08 09:46 AM

I have a rather specific question. I'm building another trailer, but this one will have suspension for each wheel. I've been looking for a suitable (cheap) shock absorber for the purpose. something with a spring and damping. Ideally not more than 8inches long. Stroke of about 2inches. Compression achieved with weights of 80lbs.

In what field of human endeavour would one find such a thing?


So far the front shocks from ATVs seem closest (rear bicycle shocks seem to have little intrinsic stroke). I imagine the spring would have to be replaced with something softer, but the other characteristics seem to fit, more or less. However they generally seem too large for the purpose. I hear the 'shock' on the BOB Ibex(?) doesn't actually have any built-in damping. There are similar cheap, purely sprung shocks on ebay, but none have damping, which is really something I want.

Any suggestions welcome.

Regards,
AR.

Kimmitt 05-30-08 11:20 AM

That sounds like a go-cart kinda thingy, I dunno.

badmother 05-30-08 12:26 PM

Could be built with two 20" suspension forks. I`we seen pictures of one. Tall and heavy I guess.

astronomerroyal 05-30-08 02:09 PM

Actually Go-cart shocks would be very good. The ones I had seen online were a little long, but there might be more suitable ones out there.

As for forks, that crossed my mind, but yes, too bulky. I had considered using 16" rigid forks oriented horizontally, combined with a regular shock. Overkill I concluded. I can make the chassis parts myself, it's only the suspension that leaves me at a loss.

Thanks. I think I'll pursue the go-cart shocks. Never having seen a go-cart I had no preconceived idea.

bloompedal08 06-04-08 07:13 PM

Just an idea I had considered...why not support the bed of the trailer with a series of short rubber or bungee straps? The straps could attach from the frame or chassis of the trailer to the bed along several points and provide a uniform vibration damping system. Granted, the straps would have to be short to allow for space considerations between the bed and the frame, but it might work, if you have enough of them and if they are of the proper elasticity.

astronomerroyal 06-06-08 11:53 AM

Thanks for the reply. I recently saw this trailer;

http://www.cargobicycletrailer.com/

and thought that it was a good way of lowering the centre of gravity, and adding bungees instead of straps would be an interesting approach to suspension.

I'd like the chassis (not just the load) to be suspended, so as to reduce the activity at the hitch. I'll probably just stick with independent wheel suspension and see if something (i.e. a good idea) turns up. I'm stuck on almost all aspects of the design, given my limited materials and tools.

lynnala 07-15-08 06:03 PM

How long of a trailer would you say you needed to carry 8ft. pieces of lumber? Could you/have you carried 12ft. pieces?

bikesatwork 07-19-08 05:24 AM

Quote:

Originally Posted by lynnala (Post 7067043)
How long of a trailer would you say you needed to carry 8ft. pieces of lumber? Could you/have you carried 12ft. pieces?

At a minimum, the distance from the front of the trailer to the axle should be at least half the length of the load. This will put the center-of-mass of your cargo ahead of the axle. So, for an 8' load, you want a front-to-axle distance at least 4' long. For a 12' load, at least 6' long.

Below is a picture carrying an extension ladder a little over 12' in length on a B@W #96A trailer. Note how the axle is behind the center of the ladder.

http://www.bikesatwork.com/posted_im...-2_cropped.jpg

If the distance is too short, and if you load is heavy, the trailer will be back-heavy and lift your bike in the air when you get off. A back-heavy trailer also reduces your traction.

lynnala 07-19-08 02:55 PM

Quote:

Originally Posted by bikesatwork (Post 7091462)
At a minimum, the distance from the front of the trailer to the axle should be at least half the length of the load. This will put the center-of-mass of your cargo ahead of the axle. So, for an 8' load, you want a front-to-axle distance at least 4' long. For a 12' load, at least 6' long.

Below is a picture carrying an extension ladder a little over 12' in length on a B@W #96A trailer. Note how the axle is behind the center of the ladder.

http://www.bikesatwork.com/posted_im...-2_cropped.jpg

If the distance is too short, and if you load is heavy, the trailer will be back-heavy and lift your bike in the air when you get off. A back-heavy trailer also reduces your traction.

Thanks, that's great info!

HandsomeRyan 07-24-08 07:13 AM

I just picked up some schweet 10" pnumatic tires on sale from Harbor Freight for $4.99 each.
http://www.harborfreightusa.com/usa/...o?itemid=30900

10" is a little smaller than I'd have liked but the price was right. The wheels are rated to 300lbs. and they have ball bearings for smooth rolling. While not as fast or as light as the larger nylon wheels used on most trailers, these wheels will allow for insane amounts of weight to be hauled. They also cost about 1/4 of what the 16" wheels I put on my last trailer cost.

I am still playing with a couple ideas for what type of trailer to build but I have worked out how to make a super-duty axle. The wheel use a 5/8" diameter axle so I got some 5/8" bolts that were about 8" long and cut the heads off them with my chop saw. I'll weld the now-headless bolts into both ends of a piece of 3/4" square tubing with just enough bolt sticking out to secure the wheels with lock nuts. (I'll try to remember to get pics) This will serve as a super-beefcake axle for the trailer. Below is an aski art representation of what I'm planning:

\\\\\\__[][][][][][][][][][][][]__\\\\\\

The slashes are threads, the underlines are the unthreaded sectons of the bolts, and the brackets are the square tubing. I'll use nylon lock nuts to hold the wheels onto the axles.

Depending on what I decide the trailer should be, I'll either bolt the axle to a plywood base or I'll weld a frame from more of the 3/4" square steel tubing.

astronomerroyal 07-25-08 04:09 PM

Other than the Bob Ibex does anyone know of other trailers with suspension (homebuilt efforts included)? I'm currently building one - almost finished - but am not entirely happy with the design and was looking for some ideas.

Unless it's done really well I'm starting to feel that adding suspension to a trailer is rather counterproductive; adds weight and weakens the infrastructure. That said, it was quite interesting thinking of all the ways to add suspension to a trailer.

Keep up the good work.

lynnala 07-25-08 09:47 PM

I've got a set of those pnumatic 10" tires on a wagon, will they work with a trailer? Maybe doubled up?

astronomerroyal 08-04-08 01:52 PM

Trailer #3 - with suspension.
 
3 Attachment(s)
In case anyone else tries to make a trailer with suspension. In this case it's for ferrying photographic equipment - and the inevitable groceries. My #1 trailer has proved to be slightly too small and I fancied making my final effort a relatively ambitious one.

After several weeks of gurning and much headscratching I put a prototype together. The wheel sections are hinged at the back. The spring is roughly 6" long rated at about 40lbs/inch. Apparently the damper is called a 'belt tensioner damper' and belongs inside a BMW's engine. It seems suitable, perhaps a little too well damped. The result is approximately 2" of useful travel with no bouncing (a criticism of the Bob Ibex, I believe). The spring can be preloaded with tension by adjusting the U-bolt thing at the bottom end of the spring. A decent grocery trip should cause no more than 0.5inch of static sag, the remaining 1.5" reserved for potholes.

As for tips, I recommend building one side of the trailer and using the pieces as templates to make the other side e.g. clamping a finished and unfinished piece together and drilling through the pre-existing holes into the unfinished piece. The result should be a mirror-image. I've always found this to produce highly symmetrical chassis and nicely aligned wheels.

As for springs, twice I underestimated how stiff the spring would need to be. The final choice was basically the stiffest my hardware store had. Design around the available stock springs because they often don't come nicely organised by rating, and custom jobs are expensive.

wheel-wheel =20"
Trailer bed is 5.5" off ground. This produces a very stable trailer. Althgough not yet attached the hitch will be a universal coupling (as in trailer #1, somewhere on this website). The upgrade from 12.5" to 16" wheels seems to have been a good move.

The weak point of this trailer would be the lateral rigidity of the wheel sections. Also the chassis probably need reinforcement at the mid-section.

Does anyone know how to paint aluminium properly? My previous efforts have not lasted, the paint comes off very easily. I sandpapered, cleaned, rinsed, primed and painted them, but might've been using the wrong products.

Cheers.
AR.

HandsomeRyan 08-08-08 09:01 AM

Quote:

Originally Posted by lynnala (Post 7137297)
I've got a set of those pnumatic 10" tires on a wagon, will they work with a trailer? Maybe doubled up?

I'm not sure that I understand what you mean by doubled up?

I'm using them on a custom built trailer, they will not work as a direct replacemnts on commercial trailers without some serious modification.

HandsomeRyan 08-08-08 09:05 AM

Quote:

Originally Posted by astronomerroyal (Post 7203348)
Does anyone know how to paint aluminium properly? My previous efforts have not lasted, the paint comes off very easily. I sandpapered, cleaned, rinsed, primed and painted them, but might've been using the wrong products.

Very nice work on the trailer. :thumb:

To answer your question-

You need to scuff it up a bit with scotchbrite, or something similar, followed by an Acid etch bath and then alodine the part. (The alodine is a chemical conversion process, which allows the paint to stick, turns it a bit of a gold color.) At his point the part needs to be cleaned with the proper solvent to remove any oils or other impurites from handling, if this is followed by a quality epoxy (two part) primer, and epoxy paint. It will hold up really well.

A middle of the road solution, would be to scuff it up well, and clean it well with solvent, and put a light coat of quality epoxy primer, something like DP40 or DP70. The put one or two light to medium coats of a good epoxy paint. The reason I say light, is even though this will make a tough coating, it will be subject to rock strikes and thus chipping. If the paint is thick it will often chip easier, and be harder to sand and paint over in such a way to hide the chips.

astronomerroyal 08-09-08 07:21 AM

Quote:

Originally Posted by HandsomeRyan (Post 7231981)
To answer your question-

Thanks for the paint info. Sounds definitive, and somewhat more complicated than I had envisaged. I'll ask at my local hardware store.

How2 08-09-08 06:18 PM

Quote:

Originally Posted by HandsomeRyan (Post 7123489)
I just picked up some schweet 10" pnumatic tires on sale from Harbor Freight for $4.99 each.
[U][COLOR=#000020]I am still playing with a couple ideas for what type of trailer to build but I have worked out how to make a super-duty axle. The wheel use a 5/8" diameter axle so I got some 5/8" bolts that were about 8" long and cut the heads off them with my chop saw. I'll weld the now-headless bolts into both ends of a piece of 3/4" square tubing with just enough bolt sticking out to secure the wheels with lock nuts. (I'll try to remember to get pics) This will serve as a super-beefcake axle for the trailer. Below is an aski art representation of what I'm planning:

\\\\\\__[][][][][][][][][][][][]__\\\\\\

The slashes are threads, the underlines are the unthreaded sectons of the bolts, and the brackets are the square tubing. I'll use nylon lock nuts to hold the wheels onto the axles.

Depending on what I decide the trailer should be, I'll either bolt the axle to a plywood base or I'll weld a frame from more of the 3/4" square steel tubing.

Sounds interesting Ryan. Please take lots of pictures. I look forward to seeing your final product. (with or without a Santa.. LOL)

talleymonster 08-09-08 07:13 PM


That is awesome! It gives me some good ideas!! I love DIY stuff!

crackerdog 08-10-08 09:24 AM

If you are going to paint aluminum with regular paint, you have to use aluminum/galvanized primer. Regular primer doesn't work.

chrome frame 09-11-08 07:58 PM

I'm getting ready to start building a trailer with some 1.5" square aluminum channel I have laying around. It would be very helpful (for me and others) to see some detailed pictures (close ups) of hitch and receiver solutions as well as different ways of mounting wheels. Homemade and commercial welcome.....

HSean 10-23-08 09:50 AM

........
 
Regarding suspention trailers, I have some ideas that are easy and will proberly work, one is leaf springs, lots of car trailers have them, they come in many sizes, get some old ones remove the smalles piece and use those, trucks have em to

http://www.dodge.com/shared/2008/ram...eaf_spring.jpg

the other alternitive is the springs from a bike I own, they are adjustable to, I don't have a picture on how to install them but put the rear wheels on two long arms on each side of the inner of the wheels and make them pivet from front of trailer with the shocks holding them to trailer by the axel, wich will proberly work good, i have a pic of those shocks but any may work, I have the same bike as this, it has good shocks

http://img.photobucket.com/albums/v3...OW67836611.jpg

astronomerroyal 10-27-08 09:19 AM

1 Attachment(s)
the suspension trailer I made in post #38 was deemed a failure because the overhead required to make a suspension system added considerably to the weight. Also, the intrinsic flex of the trailer bed was comparable to the suspension travel. Also the suspension compromised the wheels' lateral strength. Adopting a prebuilt suspension system from a bike might be a solution, but is probably overkill. The leaf spring idea mentioned above, is an idea worth considering, but could easily add too much weight. simply building a rigid trailer and suspending the load with some bungee cords is probably the easiest of all solutions.

I think it's a case of solving a problem that doesn't exist (I hate it when people say that.)

Instead I built another (number 4) rigid frame trailer, which has a perfect (for my purposes) geometry: 16" wheels with axles raised ~2" above chassis, makes a big difference in stability. Room for two large tubs. My personally favoured Universal joint hitch system.

It's pictured below as a beer train (front trailer). My orignal trailer (number 1) attaches to the rear. the universal joint approach makes these trains very easy to put together <- this is my 'construction tip', which I shall repeat ad nauseum.

badmother 10-27-08 10:13 AM

Show us the universal joint solution plse.

Trailers looks great.

astronomerroyal 10-27-08 08:31 PM

Post 73 in the 'Post your trailer' sticky thread shows the universal joint hitch. Mine's from the steering column of a golf cart.

fenderbender 11-18-08 08:01 AM

Diy trussframe trailer buildplan?
 
Truss frame trailer measurements/buildplan?

I remember seeing a buildplan somewhere on the web for a truss-frame trailer similar to the one previously sold by Bikes-At-Work. Can't find it now so anyone here have a link to this site? If not, could someone please scan and post here alt. mail me a buildplan?
Found a great pictorial on flickr but sure could use the measurements for a medium size version!

http://farm1.static.flickr.com/220/5...ff8983d8_m.jpg


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