putting research into practice: from a steel city drawing...

EWB-UK National Research Conference 2010 ‘From Small Steps to Giant Leaps...putting research into practice’

Hosted by The Royal Academy of Engineering 19

th February 2010

Panel Presentation: Putting Research into Practice Author: Jon Leary Institution: University of Sheffield 1

Putting Research into Practice: From a Steel City Drawing Board to the Heart of the Maya Jon Leary

The University of Sheffield

[email protected]

Abstract

Maya Pedal produces bicimáquinas (yes, bicycle machines!) in rural Guatemala from abandoned bikes sent over by the container-load from the US and Canada. From the bicilavadora (bicycle washing machine) to the bicimolino (corn grinder), their machines provide an opportunity for people to improve their daily lives without having to resort to expensive electrical or dirty diesel alternatives. I worked with Maya Pedal to design the bicibomba movil (mobile bicycle powered water pump) for irrigation and general water distribution. Unlike Maya Pedal’s other static designs, it is completely portable. It can pump over 26m vertically and on flat ground, such as when irrigating fields, it achieves a flow rate of 40 l/min (equal to about 3 normal showers). With the aid of an EWB bursary, I travelled to Guatemala to put what I had done so far into practice.

Keywords: Guatemala, bicycle, machine, Sheffield, mobile, water, pump

The Research: an Idea is Born in the City of Steel

When asked to make something useful out of rubbish, a bicycle powered water pump generally isn’t the first thing that springs to mind. However, this was the question posed to me by my supervisors at The University of Sheffield during the final year of my undergraduate Master’s in Mechanical Engineering [2]. After a month or so of brainstorming and trawling the internet, I stumbled upon Maya Pedal [1]. They are an NGO based in rural Guatemala - the homeland of the ancient Maya, and today their descendants - and as I’m sure you have already have guessed, they build bicycle machines.

Maya Pedal began in 1997 when a group of Canadians known as PEDAL [3] (Pedal Energy Development Alternatives) coordinated an appropriate technology project involving the reuse of unwanted North American bicycles in the highlands of Guatemala. In 2001, Maya Pedal as it is today was born. Following a vision for sustainable development in Guatemala, a board of directors consisting of local Mayans took control of the organisation.

The concept of transforming the humble bicycle into a machine for harnessing the power of a person’s legs is not unique to Maya Pedal. During background research, I found plenty of interesting home-made bicycle machines and even a Thai Hotel that made their guests do the work with a novelty bicycle powered irrigation system for their garden! However, Maya Pedal is different because it produces bicycle machines in a place where they can really make a difference to people’s daily lives. Grinding corn, washing clothes and shelling macadamia nuts by hand are all time consuming tasks that are still done in the same painstaking way as the Mayans did thousands of years ago. As a result, many Guatemalans resort to using expensive electrical or environmentally damaging fossil fuelled machines to perform these tasks for them. In many cases though, bicycle machines can act as a direct replacement for their conventional counterparts. With the added benefits of zero fuel costs (unless you include the food eaten by the peddler), lack of environmental impact and the ability to operate in even the remotest locations, it is clear that they truly are a sustainable energy source.

Amilio Aviles, a Californian aerospace engineer who at the time was working as a volunteer for Maya Pedal, informed me that out of their many bicycle machines, there were 4 in particular that were in need of improvement. The bicivibradora de tejes (bicycle powered tile vibrator) is used to agitate freshly poured concrete roofing tiles and thus force out tiny air bubbles that would otherwise weaken them if trapped inside. The machine was built for a local man running a small family business, however he was unable to make a profit from it as he needed 3 people to operate it: one to pedal, one to mix cement and one to hold the tile mould. Improving the machine would not only mean more income for the family, but it would open up this source of income to others and make the roofing tiles (which are superior to corrugated metal sheets) available to more people. Many local people grow macadamia nuts. Maya Pedal has a machine that strips the husk, but is unable to remove the hard shell. Consequently, the nut growers are forced to sell the unshelled nuts for a lower value, as cracking them without smashing the nut is difficult and time consuming. Another popular occupation is selling licuados (fruit smoothies); the bicilicuadora (bicycle powered blender) allows street vendors to set up their stand wherever they want as no electricity is required. However, the machine is bulky and difficult to transport: a mobile machine would be preferable.

The final machine was the bicibomba para pozo (bicycle powered well water pump). The current machine was capable of drawing water from up to 30m below the surface and was a very popular design. However, many farmers lived on steep inclines and wanted to distribute the water once it had been extracted from the well. One farmer had specifically requested a pump to transport water from a nearby spring to his house – a distance of 150m horizontally and 75m vertically. Amilio suggested using an off-the-shelf pump and adapting it for bicycle power, as they had done with a pre-manufactured grinder for the bicidespulpador de café (bicycle powered coffee depulper) and hand-mill for the bicimolino (bicycle powered corn grinder).



th February 2010


After some deliberation, I set off to the drawing board to design a bicycle powered water pump, a bicibomba. One of the biggest challenges was shifting the water over such a large distance (150m across, 75m up!). A healthy male can only reliably maintain a power of around 250W when peddling on a bicycle [4]. Conventional centrifugal electric water pumps with a power rating of 300-400W are only capable of pushing water up to 40m vertically at the very most. It therefore looked as if the target of 75m would be impossible to achieve. At the time, there were a number of designs on the drawing board, but one started to stand out. The design shown in Figure employed an A-frame base to lift the bicycle’s back wheel off the ground, where it could then be used to friction drive a converted off-the-shelf electric centrifugal pump.

Outlet

Hose

Inlet

Hose

Pump Assembly - driving roller

- cylindrical bracket

- pump head

Axle

Grips

Supporting Frame

Axle Grip Tighteners for

Lateral Adjustment

Radial Adjustment

Slots

Hose

Clip

Bicycle

Rear Tyre

Key

- Bicycle - Manufactured parts - Parts of original pump

- Other purchased parts

Figure 1 - CAD Illustration of the A-frame style design [2]



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The distinguishing feature of this design was that after pumping had finished, the frame could be flipped upside down and transported on top of the rear wheel of the bicycle like a pannier rack (Figure ). The whole set up could be moved from one spot to another in a matter of minutes; users could pump from the bottom of the hill to a mid-way tank until full, and then continue pumping from the mid-way tank to the top of the hill. The number of mid-way tanks can be increased indefinitely, effectively making the pumping distance unlimited. This greatly increased the flexibility of the machine and to reflect this, we gave it the name bicibomba movil (mobile bicycle powered water pump). The design was also highly adjustable to different bicycles – Figure demonstrates how axle grips allowed lateral adjustment to fit a range of axle lengths and a sliding rack on the frame allowed the pump to move up and down (radially) to accommodate various tyre sizes.

Having settled on a design, the next step was to take it off the drawing board and into the real world by building a prototype. Based on Amilio’s descriptions of available pumps in Guatemala, the Clarke TAM 105 centrifugal electric water pump was chosen for the UK prototype as it was cheap and a close match in performance (max. head=35m, max. flow-rate=40l/min, power=350W). Some engineering analysis [2] showed that using the armature of the electric pump as a roller to be friction driven by the rear tyre would rotate the pump at a suitable speed and that the bicycle’s gears could be used to optimise this. Further analysis [2] was conducted to determine whether the design was sufficiently robust. With some minor modifications, construction began and a few weeks later, the prototype was complete.

The machine had been designed to be as simple to build as possible, however after the manufacturing was completed, it was established that certain parts should still be simplified further. Maya Pedal’s workshop consisted only of hand tools, a few vices, a bench grinder, a chop saw, an arc welder and a drill press. A couple of parts in particular had required the use of milling equipment, a lathe and boring tools. To manufacture these parts at Maya Pedal would have required an expensive and time consuming trip to the machine shop in the next town. Therefore, significant modifications would be required before the design could practically be produced in Guatemala.

Nevertheless, a working prototype was ready for testing and some preliminary trials were promising, with the pump functioning as planned. The acid test for a pump, however, is to find out how much water it can pump at varying heights/heads. Normally, this would be done in a test rig under controlled conditions to give accurate results, but it was decided to go for an ‘alternative’ approach: use a staircase to vary the height and measure the time taken to fill a bucket at each elevation (see Figure a). From this data, Figure b was plotted to compare the performance of the bicycle machine with that of the original electric pump. The test began at ground level, and found that the flow-rates achieved (male peddler: 40l/min, female peddler: 30l/min) were very similar to those of the unmodified electric pump (40l/min). As we made our way up the stairs however, the peddlers began to get tired and were unable to sustain the same amount of power. The male peddler’s power dropped from 350 to 200W and female’s from 150 to 80W. The maximum heights/heads reached by the male and female peddlers were 26m (incidentally, also the height of the top of the staircase) and 13m respectively. The step change in power delivered by the male peddler at heights/heads above 20m appears to have been psychologically induced by knowing that the end of the test was near.

Other sources of error included friction in the pipes, leaky couplings and human error in timing. But, however flawed the experiment may have been, it had proved that the pump worked. And it worked well. It had been shown that the pump could lift water the required vertical distance of 75m in just 3 stages, or less.

That said, there was still a long way to go before the design could be useful in Guatemala. The original plan was to produce a set of instructions on the manufacture and use of the bicibomba movil to send over to Maya Pedal. However, a few months before the end of the project, I had successfully applied to both EWB and The University of Sheffield’s Wilson Memorial Fund, for financial support to travel to Guatemala myself. I was planning to work on the design in Maya Pedal’s workshop to demonstrate what I had done so far and draw on the organisation’s extensive experience with bicycle machines to truly optimise the bicibomba.

Transportation Mode Pumping Mode Figure 2 – The design could be quickly and easily swapped between functions (adapted from [2]).



th February 2010


Bicibomba Movil

Inlet Hose

Outlet Hose

Measu

red

Pu

mp

ing

Head

Supply

Barrel

Outlet Hose Nozzle

Average Water Level

in Supply Barrel

Measuring

Bucket

Assistant

Figure 3 – a) Experimental set up for performance testing of the Bicibomba Movil

with b) comparison of recorded data against theoretical power inputs (adapted

from [2])



th February 2010


Putting it into Practice: Tales from the Guatemalan Highlands

Almost a year later, in May 2009, I touched down in Guatemala City. The view from the air was amazing: towering mountains surrounding rows and rows of buildings, spilling up and down the various ravines that punctuated the city. However, appearances can be deceptive; Guatemala City is notorious for its gangs. The longest civil war in Central American history (1960-1996) has left many people with no other choice than to use the weapons that they have been trained to use during the conflict to take what they need to survive. Guatemala is definitely a developing country, and a place of many contrasts. Guatemalans are very aware of their more affluent North American neighbours, the influences of whom can be seen in the most unlikely of settings. For example, subsistence farmers carrying cell phones who live in mud brick houses with televisions inside. The cell phone is likely to be an old American design and the television may well be black and white, but it is this integration and re-use of technology from Guatemala’s wealthier neighbours that have made the re-use of old bicycles such a success. Although most of the population is not in danger of starvation, many Guatemalans are subsistence farmers and Maya Pedal’s machines are designed to boost their income and increase their quality of life, whilst encouraging self-sustainability.

Maya Pedal is based in San Andrés Itzapa: a small, indigenous town around an hour to the South West of the capital in the mountainous region of Chimaltenango. Before making my way to Maya Pedal, I spent a few weeks attending one of nearby Antigua’s world-renowned Spanish language schools. I continued to study here on the weekends and by the end of my 4 months, was proud to say that I was verging on fluency. Arriving in Itzapa after the luxurious Antigua, I have to say that my first impressions weren’t great. Concrete breeze blocks and rusty rebar were the building materials of choice, whilst the small stream running through the centre of the village seemed to double as a rubbish bin. As we walked through the market towards Maya Pedal, I realised that even though we stuck out like sore thumbs – 2 Europeans with humungous backpacks towering above a sea of traditionally dressed Mayans – no-one was staring at us. Maya Pedal had been in the town for 13 years now and had become well integrated into the local community.

When we arrived at Maya Pedal, all the volunteers at that time were American. However, people came from all over the world to work at Maya Pedal. During my time there, there were a pair of Columbian journalists writing an article for the National Geographic en Español, a French bike mechanic on his way from the US to South America overland, a whole family from Californians, a Peruvian engineering student, an Australian engineer and a few Spaniards. The whole process of volunteering at Maya Pedal is a lot less formal than most organisations that accept international volunteers. People can just wander in and out as they please, help out where they can and, in exchange for their efforts, receive a place to stay. On one hand, this gives great freedom in what people do there; but on the other it can become chaotic. It took me a good week or so to get into the swing of things and start to realise exactly what was going on.

Co-ordinating this unruly mass of volunteers is Carlos Marroquin. Founder, director and responsible for the day to day running of the place, Carlos is Maya Pedal. Carlos is an extraordinary man. He was born and bred in Itzapa and is highly respected in the local community. But not just here: as the inventor of the majority of Maya Pedal’s bicycle machines, his work has been recognised internationally. He has spoken at MIT in the US, arguably the best technical university in the world and has been invited to talk at the International Development Design Summit.

During the first month or so, we were swamped with an order for 26 bicibombas para pozo (the original bicycle powered water pump for extracting well water). Each machine took around 3 days worth of labour, so when the number of volunteers dwindled down to just 2, progress virtually ground to a halt. But, such is the way of Maya Pedal, and the next week we had shot up to 9 and were struggling to find space to put people! Just as we began to get close to finishing the pumps, we got news that a container-load of bikes would be arriving from the US, at 6am the next morning! When the container finally arrived (only 3 hours late, but virtually on time by Guatemalan standards), so did a hoard of Mayans! The board of directors, as well as their families and friends had all been roped into helping out. 5 hours and 500 bicycles later, the place looked like someone had exploded the world’s first bicycle bomb over it. The next week was spent cataloguing the bikes for tax purposes and organising them within the building. Only around a quarter of the bikes that Maya Pedal receives actually become bicycle machines. The rest are generally in good enough condition that they can be repaired and sold off to subsidise bicycle machines for communities that really need them. When all the new stock had been put away, work on the pumps continued. A few weeks later, they were finished and Carlos hired a huge truck to take them up to a town near the Mexican border. One pump was installed as a demonstration and the rest were left with the community.

Now that the bicibombas para pozo were out of the way, it was time to start on what I had come here for: the bicibomba movil. Over the past few months I had learned so much. I came to Guatemala barely able to string a sentence together and incapable of crafting anything vaguely useful in the workshop. Now I was laughing and joking with Carlos and was welding together bicilicuadoras with my eyes closed! I was ready to create something innovative. I discussed the design with Carlos and within a couple of minutes, he had already thought up a replacement for the cumbersome A-frame I had designed. He proposed using a pair of seat tubes and seat posts to provide the vertical adjustment required to accommodate differing tyre sizes. It was an excellent idea, as the components had originally been designed to provide vertical adjustment for the saddle. He also proposed using angle iron to construct a stronger, lighter frame and using the original pump casing instead of manufacturing an intricate cylindrical casing with a boring machine (that Maya Pedal do not have). I went about constructing a prototype and a week or two later, it was ready. It didn’t look very pretty, but it worked. The seat post height adjustment was a little tight, but that could easily be fixed next time.

Carlos saw the potential of the design and already had a customer in mind. The next week we began construction of the first official bicibomba movil. Carlos also had further improvements up his sleeve, such as replacing the fiddly triangular frame with a simpler square one, simplifying the pump attachment to use only one bolt instead of four and the addition of an internal nut and bolt to stop



th February 2010


the socket constantly falling off of the axle grip. The result was a machine that was easy to build, robust and professional in appearance. Unfortunately, Carlos had done all the measurements by eye and consequently when we went to attach it to a bicycle, we realised that it didn’t fit! A little chop sawing and re-welding put it into shape though, and before long, it was ready for testing. The pump worked beautifully, as did all the adjustable features. It was great to see how far the design had come (see Figure ).

Carlos had been speaking to the customer who had ordered the bicibomba movil and apparently, he had also asked for a bicigenerador de electricidad (bicycle powered generator). It made sense for us to try and combine the two into a single machine. An electric motor could easily be attached to the frame in place of the pump and operated in reverse to charge a battery, which could then transported on top of the frame, as shown in Figure e. Figure outlines the major adjustable features of the machine. Unfortunately, my time at Maya Pedal was over before we were able to test the bicigenerador. Other volunteers have informed me that it worked well though, and that the gentleman who ordered the machine was very happy with it.

After four months, my time in Guatemala was up. I was really sad to leave. I had learned so much about the culture, the language, the tools of the workshop, bicycle machines and life in general. It was great to see a design through from the very first step, right down to building the first production model with my own hands. My only regrets were that I couldn’t stay a bit longer to see the pump in action in the field, or do some more with the generator. Fortunately though, I’m still in regular contact with Maya Pedal today. Carlos informs me that they’ve now sold 6 bicibombas movil, at 1,200 Quetzales (around £100) a piece. I recently completed a construction manual

Figure 4 – Evolution of the bicibomba (clockwise from the top left): a) The original

bicibomba para pozo [1]; b) myself testing out Maya Pedal’s static design for a

mini-bomba; c) myself riding the first prototype of the bicibomba movil in the UK;

d) Carlos Marroquin demonstrating the second prototype in Maya Pedal’s

workshop; e) and finally Carlos Sr., Carlos Jr., Jamie and myself outside Maya Pedal

with the final design.



th February 2010


for a bicibomba movil, which will hopefully help Carlos remember the measurements and allow new volunteers to get building independently. It is also freely available on Maya Pedal’s web site [1], so that anyone anywhere can have a go at making one.

Acknowledgements

I’d like to thank both The University of Sheffield’s Wilson Memorial Fund and EWB’s UK Bursaries for providing funding for the project. Also to my girlfriend Caitlyn for spending a whole day climbing up and down staircases to test the pump! Thanks to my supervisors Dr. Steve Bradbury and Geoff Heppell for all their excellent advice. I never would have even started the project if it hadn’t have been for Amilio Aviles, the volunteer who sent me so much information during the design stage in the UK. And finally, thanks very much to Carlos for all his advice and for always having a smile on his face!

References

1. Maya Pedal. [cited 2010 31st January]; Available from: www.mayapedal.org.

2. Leary, J., Design of a Novel Product Using Waste Material, in Department of Mechanical Engineering. 2008, The University of Sheffield; Available from www.mayapedal.org.

3. PEDAL (Pedal Energy Development Alternatives). [cited 2010 31st January]; Available from: http://www.pedalpower.org/.

4. Whitt F.R. and Wilson D.G., Bicycling Science. Vol. 2nd Edition. 1982, Cambridge, UK: MA:MIT Press.

Figure 5 – The dual-function machine: la bicibomba y generador movil

Pump

Axle-grip

Axle-grip

Motor

Height

Adjustment

Height

Adjustment

Locking

clip

Locking

clip

http://www.mayapedal.org/

http://www.mayapedal.org/

http://www.pedalpower.org/

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