Steel can create a very durable and rugged car that will often outlast the animals that are drawing it. However aluminum is as durable and element resistant as well as being extremely lightweight and is often the material of choice for many countries. Pneumatic or inflatable tires also have been a boon to carts by helping to absorb some shock as well as to distributing the weight over a wider surface without significantly increasing drag on the vehicle.
Aluminum casting is already a technique that is widely used in many parts of Africa and other developing countries. Africa, usually to make cooking utensils and the like. "Aluminium wheels with integral roller bearings could be made by these artisans and would provide a very low cost solution to the wheel and bearing problem." (Oram173) See figure 6 below:
These designs element the ordinary friction involved in a typical axle joint design made from wood as well as the quick wear and tear on the material over a shorter period of time.
There have also been considerable important in the foundation of journal bearings. Journal bearings are fundamental engineering component that supports and positions an object while allowing that object to rotate.
Bearings made of wood have long been used in cartwheels, windmills, lathes, and other technical devices Archeological evidence shows that wooden wheels and bearings were first used in the Tigris- Euphrates valley circa 3500 BC These solid cart wheels were crafted of flat planks and rotated on fixed wooden poles. (Sathre & Gorman 48)
Slowly evolving to lighter spooked wheels and the use of bearing lubricants which have been document to the thirteenth century BC, journal bearing have evolved even further in the current epoch. Leonardo da Vinci studied the friction and wear of bearings in the 15th and the recent industrial revolution sparked great advances in bearing Technology. (Sathre & Gorman 41)
Sather and Gorman decided to research improving existing and readily available materials like wood and attempting to ascertain the ultimate combination of variables necessary to make the most efficient bearing out of that material. Since aluminum and Steel many not be available to many, having better guidelines for available materials is the next best thing. Their study discover, among other things that: higher wood density gave lower wear; Higher wood permeability gave lower wear; Permeability may be more important than density to bearing longevity; Petroleum-based lubricants gave higher dynamic friction than animal- and vegetable-based lubricants; Beeswax lubricant gave the lowest static and dynamic friction levels and so on. So changing or upgrading materials may be one way to go, but improving existing use of standard materials is another. (Sathre & Gorman 46-7) they also experimented with different varieties of wood to find the optimal type. (see figure 7)
In order to best service the owner, Animal drawn carts must meet many criteria for particular needs, but to improve them require and understating of the materials involved and most readily available to the country of use. While it would essentially be easy to manufacture and sell the perfect two or four wheeled animal cart and sell it world wide, many farmers and other citizens of many countries could not afford what might be an expensive luxury to them. So in order to completely address the needs of the owner the researcher must provide the optimal materials at the optimal cost and availability to the owner. Just as carts may be designed for a specific purpose, improvements to carts make take into consideration not only the external environment and ruggedness of the terrain but also the economic and resource environment of the owner as well as the particular animals involved in their use.
Sather and Gorman's study of wooden journal bearing is very promising and relevant for most emerging nations, but there is also, as Oram noted, the possibility of improvement through more modern materials such as aluminum construction that are also available to many nations at this time. By coming together as researcher and as global citizen many countries are also promoting economic plans that take the purchase of carts fro transportation into consideration. This could possible be the greatest improvement in the development of carts, making the best materials and most effecting engineering methods available to those who could not at first afford them. An excellent example of this is the Glovan one Ox cart which can be found in Appendix II of this report. It is an excellent example of engineering combine with locally available materials that can be of great benefit to the owner.
LIMITATIONS of the STUDY
The gender and age of the owners of the carts were not addressed here. These are certainly relevant consideration when constructing and employing carts. Not all designs and countries could be included due to the brevity of this presentation and many nations have developed even more interesting types of carts and modes of transportation.
The Golovan one-ox cart," in Land, June 1997 from Dept. Of Agriculture, sought Africa http://www.nda.agric.za/docs/Infopaks/golovancart.pdf
Light Single Drum Water Carrier." Animal Cart Programme. Development Technology Unit, Department of Engineering, University of Warwick, Coventry, England http://www2.warwick.ac.uk/fac/sci/eng/research/dtu/pubs/tr/animals/tr30.pdf
Oram. CE. "The development of low-cost animal-drawn carts." Meeting the challenges of animal traction Starkey P. And Kaumbutho P (eds), 1999 Harare, Zimbabwe. Intermediate Technology Publications, London.
Ogwang, V. "A note on improving animal-drawn transport in Uganda." Meeting the challenges of animal traction.Starkey P. And Kaumbutho P (eds), 1999 Harare, Zimbabwe. Intermediate Technology Publications, London.
Pack animals and animal drawn carts." Food and agriculture Organization of the United States http://www.fao.org/sd/teca/tools/lst/LSTP31_en.html
Sathre, R and Gorman, T. Improving the performance of wooden journal bearings Forest Products Journal Vol. 55. No. 1 1
Starkey, P. Harnessing and Implements for Animal Traction an Animal Traction. Deutsches Zentrum fur Entwicklungstechnologien Deutsche Gesellschaft fur Technische Zusammenarbeit 1989
Sustainable Rural Transport" International Council of Societies of Industrial design. 2005 http://www.interdesign2005.org.za/pdfs/feedback/AnimalDrawnCarts.pdf
Thibedi, J. Address by MEC Jerry Thibedi. South African government Information http://www.info.gov.za/speeches/2006/06102012451002.htm
The Light Single Drum Water Carrier
From "Light Single Drum"
The Glovan Ox Cart
From the Glovan one-ox Cart from "Pack Animals"
From Pack Animals
From Starkey 12 some examples of new cart materials