"Incidentally whil~t talking about muscle power, its efficiency is interesting. Ifyou assume that.a man east 2,500 to 3,000 ccllories a 4ay . .. this is equivalent to about an eighth of a ton of coal a year. Ifyou take our earlier assumption ofworking 8 hours a day for 200 days a year at a tenth of a horsepower, it means that a man treated as an engine is about 10 to 15 percent efficient. It is really very good, it is almost as good as a petrol engine and costs far less ... " P.O. DUNN Lectures on Socially Appropriate Technology POWER by S. S. Wilson, M.A., M.I.Mech.E. · Department of Engin~ering Science, Oxford University ·Oxford, ENGLAND . · ' ~ E .Jtt .... . Q) Q. C> .... Q) • Q. ~ C · ~ + 0 Q. Ill ·c: c ,_ + .... 0 ~ Ill 0 (.) October 1976 .. RAIN Page 9 0 ·100 o oer- • I -:- 0 ·60- • Mice • - 040- .. . e LemminQ 0 ·20 Frutt '~ 81! eeee • Ro~ O·IC f-. fly .- oe 0 ·6 eLacust eRot~bi-t 0·4 . . - HumminQbird • • Helico~r 0 ·2 BudQerioar • eooo • . Gull ecaw 0 ·1 f-. eSI'Ieep - . 0·8 • . ·~ PiQeon· Mone ~ Au'tamo'!'' 0·6 0 ·4 • . 1-krses . . Jet Salmon 'tranaoort0 ·21- . ... Mon on btcycle • 0 ·1 . I ·I I -i06 . -10~ 4 -10 3 -10 2 -ld 10' t<J 10 3 tc! lrJ I~ -10 I Body wt. (kg) Energy Efficiency of Different Means of Transport e Apart from the ubiquitous bicycle, still a growing field, pedal powe~ e Other uses of pedal power actually demonstrated are for c:'ln be applied to goods transport and to a.variety of stationary . ~orn milling a.nd for water pumping, in which pedalling can power uses, most of which are applicable in the U.K. as well as. Improve the output by a factor of three over manual effort. in less developed countries. The OXTRIKE, below,.is a basic· One use for the pedal pump is as a standby for a windpurnp tricycle chassis to take a variety of bodies for trans,port of · during periods of insufficient wind. · · goods or people. Profocype construction has been funded by ~mong the plans awaiting the building of prototypes is a OXFAM, and it is designed to be built from kits in any smaJl design for a two-man pedal-driven winch. One major . workshop, e.g. school/community workshops. The innova- use for such a winch is for cable ploughing and cultivation on tions include sheet.steel construction, three-speed gears, power- the lines of the '~nail,' .as described in an earlier pape.r. For ful foot brakes and a simple form of differential drive. Such a· many purposes, mcludmg small plots and allotments, the pedal vehicle fitted with box vim, hopper or flat truck body would winch may be as effective ·as a motor-driven w:inch; .be useful for OXFAM shops or for use with the OXFAM · Wastesaver project, as an alternative to a 3 5 cwt van-the . OXTRIKE payload is 3 cwt, which is more than the average load in the majority of city delivery vans. . , . OXTRIKE chassis, designed for transport of goods or people. •' ... ';t;..r • .~o.~. '•·· ' ::it :· ~) ,;; 'l7~ :i.0;~t' These excerpts are/rom "T~cbnology ·of Human .Sc{lle" by S. S. wilson. · Wilson bas been instrumental in recent development ofimproved people-powered vehicles. His more extensive essays in Lectures on · SoClally Appropriate Technology (see RAIN, june 1976) and SCientific American, March 1973, explore both the social and technological . aspects of improved bicycle transport. · · Pedal~powered diaphragm water pump, developed by IRRl for irrigation use. · · . . :?~c~roe tube · : / . . .... -----...... __ ·~ --- . . \
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