charriot trailer diagram

charriot trailer diagram

Originally uploaded by aaronforest.

New trailer design, for a flatsy-like cart that also operates as a manual push cart. The pulling arms secure the load, and this design actually uses less material than “flatsy”. I’ve designed a universal joint, made from M16 or 5/8″ nuts and bolts as well. This trailer attaches beneath the seat on a bicycle with a drop-in pin mechanism, like Bikes At Work uses, more or less. This design is heavily influenced by my work with bicycle Ambulances in Namibia.

seatpost hitch

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Originally uploaded by aaronforest.

This is the hitch I designed for the BEN ambulances. I will also use this design for my new trailer design, “Chariot”, which is built with the design principles that guide my community bike cart design project and the designs “Deep and Short” and “Flatsy”. Low cost in parts, can be fabricated with minimal experience and simple tools, etc–but this design pulls under the seat on the bicycle for operation as a hand cart as well. The BEN Namibia trailer that I am designing is based on similar technolog, but uses kink bends reinforced with 10mm rod to eliminate the need for a 25mm tubing bender, as conduit bender for 25mm OD tube aren’t strong enough to bend 25 X 1.6mm tubing, nor are they available in Namibia, nor is the radius small enough.

This hitch attaches to a bicycle seatpost (left side of photo), has a hitch pin that slides through the trailer pivot tube to allow easy removal, and a universal joint made from nuts and bolts. I am redesigning two of the pivots to spin freely, instead of on threaded surfaces, which introduce the potential for binding and unsafe operation.

BEN Namibia bicycle trailer

roll7

Originally uploaded by aaronforest.

I designed this trailer to address a need for cargo and human transport in one trailer, with better manufacturability than the bicycle ambulances. The tailgate folds down for a passenger’s legs, and a mattress and canopy can be added for comfort and safetly. Not shown: Sheet metal wheel guards.

Recently I have been starting to address another design issue that we are facing here–manufacturability outside of our own shop, of a versatile bicycle trailer that also has good human-transport capacity. I work within many of the criteria of Appropriate Technology design and implementation–and i the last 8 months of working as a bicycle cargo transport designer in Namibia, I’ve come to realize even more that so much of a project’s success is in the design of the implementation, whether it be in the private OR public sector. In the case of our bicycle ambulances, the project implementation is fairly successful currently, because there is a lot of support from BENN–but without this organization’s support, there are no mechanisms currently for the production and distribution of bicycle ambulances to continue in Namibia. (I’m hoping to change that before I leave in 4 months). However, because I designed the ambulances to be repaired in the common welding shops along all the mayor roads and in towns, the existing ambulances have a good chance of being repaired when something happens to them. The idea of a new bicycle trailer design that also has human passenger capacity addresses some of the continuity problems in relying on an NGO for a technology to be provided in a country. Such a trailer would be more simple, affordable, and would be able to exist in the private sector, with support from NGOs such as BEN Namibia for design, training, monitoring and evaluation, and quality control. A bicycle trailer is easy to design for cargo, but when you add sick human passengers, there are many more issues that come into play.

Some of the design constraints that I’ve identified thus far are as follows:

*Must be made with the following tooling: stick welder, vice, hacksaw, file, electric hand-drill, hammer, and basic hand tools. Maybe a grinder is appropriate.
*Tubing available:19mm, 22mm, 25mm, 32mm round and square tubing, often either 1.6 or 2mm wall thickness (rectangular tubing also available)
*other material available: 0.6, 0.8, and 1mm sheet metal, expanded and flat mesh, M6, M8, M10, M12, and M16 nuts and bolts…, 25mm, 30mm, and 35mm angle
*wheels and tyres available: 20″, 24″, and 26″, but if 20 or 24″ wheels are used the trailer must also fit 26″ wheels for field-servicing.
*Functionality: contain bags of flour or grain, contain buckets of liquid, hold loose items larger than 1cm by 1cm by 10cm.
*More functionality: carry passenger in reclining position, legs out or slightly bend down, with lap and chest restraints, and cushioning.
*More functionality: Prevent water, sand, and mud from entering cargo area. Have covering for sun and rain for passenger’s torso and upper legs at least.
*Complexity: lend itself to fabrication with simple jigs and fixtures, and training in manufacture in 1 week.
*Terrain: withstand rocky and steep terrain, and also sandy slopes.
*pulling: Must be operable by a bicycle AND by hand pulling for sandy and steep terrain.
*cleaning: Must be cleanable with soap and hot water. Most medical transports in Namibia will be for illnesses, often communicable, that are complications of HIV/AIDS. Sanitation is an important design criteria.

This is just a start. Does anyone want to collaborate on design? I’m listening…

Ambulance #1

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Originally uploaded by aaronforest.

This is BEN Namibia ambulance #1, before we sent it off to Katima. So far the first 14 ambulances have followed this design, with the exception of the canopy, which I modified to sag less. Ambulances 15 through 23, which I’ll make in June? I’m thinking….Bright yellow, with blue material. Because color is clearly the most important thing I have to consider at this point…. Thoughts?

for a better view of the dunes by swakop….

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Originally uploaded by aaronforest.

The sand was hot! I began the day knowing that I was going to be burning my feet, but I didn’t expect to burn the hands too. Well worth it though. The view of dunes upside down is very strange–like the tests when they turn an object like a microwave upsidedown and have you identify what it is, and it’s kind of disorienting at first. Elizabeth and I spent a weekend in Swakopmund, which was lovely really, and I spent as much time as I could taking advantage of the sand and grass, with some assurity that I wasn’t going to stick a 2 inch thorn through my body if I lay down.