Engaging Learners Through Designs That Matter: Global Awareness
Projects - Hand Operated Water Pump Modification
Mechanical Engineering Student
California State Polytechnic University, Pomona, CA 91768
Our approach to teaching must be based on sound pedagogy that helps students to “uncover” the principles instead of being told. Research indicates real learning occurs when learners are immersed in realistic situations in which they are forced to perform, get feedback, take action, and given chances to adjust their responses. While there are many ways to simulate such situations, the most effective approach to learning is having students engage in real projects – projects that can directly benefit communities and offer a unique way to learn and serve. At Cal Poly Pomona a number of service learning and global awareness projects are currently under development. These projects include the design of devices for developmentally disabled children as well as global projects such as the design of hand operated coconut de-husking machine. This paper describes the redesign of a hand-operated pump for potential use in developing countries.
This project objective is to improve upon the current cast-iron style, hand-operated water pump that is used in many developing countries as a primary means to pump well water. While few improvements have been made in the last 200 years to the current design, the goal of this project is to create a more efficient means by which water will be pumped out of the well. The main problem is that in order to use the pump, a heavy lever has to be operated which can become awkward to use and cause fatigue after pumping water for long durations. Because these pumps are used in developing countries, it is imperative to create an efficient pump that is both cost effective and easily distributable across the world. The most important considerations in creating this pump is the ability to easily retrofit current pumps in remote locations, requiring very few tools to install the device, not requiring electrical or other power, and being able to quickly install the device for little down time. At the root of the project is the goal to create something that will help these people in developing countries who use these pumps regularly make pumping well water less of a chore and increase their quality of living in some way by doing so. Water Pump Information and History
Designed in the mid 1700s, hand-operated water pumps are still being used throughout countries such as India, Ghana, and Ethiopia. While some changes have been made, the integrity of the design has remained virtually untouched for nearly 300 years. While some pumps have been installed recently, most have not been modified or replaced in over 50 years. Many of the developing countries settle for what they have because they do not have the means to improve upon their current conditions. Many groups and organizations are trying to improve the daily living conditions for many of these people; drinking water is one of the most important improvements to be made.
In Ghana, in a few remote villages, these pumps are running non-stop supplying water to the people. When discussing the situation with a family friend who was stationed in Ghana for two years working with the Peace Corps, he told me that the current design of lifting and lowering the lever is horrible and could easily be improved. Although most people have learned to use it quite effectively, a newer, more efficient design would be a welcome change to these people. The current design cannot be any simpler. With very few parts to break, and not many components to service, the pumps are fairly reliable. Even pumps that have been around for over 50 years are still functional. This factor alone is one reason to leave the design alone, but the benefits of increased efficiency override the downside that a few hours of service and maintenance might cause.
Fig. 1: A Typical Hand Operated Water Pump
Potential Design Concepts
Many designs were conceptualized for this project; most ideas were foot powered, but a few were hand-crank style, with the assumption that the design of the pump should not be
altered too dramatically; the objective was to simply remove the awkward lifting required in the current design. All of the hand powered designs were eliminated, as the human body simply does not offer enough sustainable power through the use of a persons arm. All of the logical design changes would require the use of at least one foot, or possibly two feet while seated. One close candidate for a final design was a bicycle style pedal system. Although it would require the individual to sit, it would allow the person to go on for hours with minimal effort expended. This design was not carried forward due to the complexity of the system. It required chains and sprockets to function nicely, and overall too many parts that could fail or would require maintenance.
Chosen Concept - Detailed Designs
The two chosen designs were selected by taking four things into account: design simplicity, ease and cost of manufacturing, reliability and serviceability, and the overall improvement of the pumps efficiency. While both of the chosen designs are not as simple as some of the other conceptual designs, they seem to offer the best mix between a significant design change that would benefit the user, and a system that did not have too many moving parts and would allow easy assembly and maintenance, with no single part being super expensive.
1. Foot Operated with Spring Return
The first design is based off of the compact foot operated bicycle pumps. The design
requires minimal changes to the pump, and is a complete bolt-on solution. Only one
part needs to be removed from the current pump, and seven parts added, all
assembled with a single wrench by hand.
Main Parts of the Pump
The foot operated spring return pump consists of seven parts: The new pump arm that replaces the current arm at the top of the pump, the two linkages connecting the new pump arm to the foot pedal bars, the foot pedal and its two connecting bars, a spring, and the 2-piece clamping collar to mount the foot pedal assembly.
Fig. 3: Foot Operated Sprint Return Fig. 2: Foot Operated Spring Return
Pump Back View. Illustrating the Pump Front View. Illustrating the
user’s foot position behind the pump, simple linkage setup utilizing very
allowing a bucket to sit in front. few parts.
Mode of Operation
To use this design to pump water, the operator has to step down onto the foot pedal for the pump to start pumping. The spring in the system (not shown) raises the foot pedal back up, recovering the system to be able to pump again on the down stroke. The strength required to overcome the spring force is minimal. When thinking about the amount of force a person can push downward with, the added 20-30 lbs of spring force is almost negligible. Even a lightweight person
weighing 70 pounds would be able to easily put their entire weight on the foot
pedal to create enough force to pump water and overcome the spring return. 2. Foot Operated – Singer Sewing Machine Style
This second design is more complicated and slightly less cost effective. The design, however, is very efficient, allowing the user to more comfortably pump for long durations as long as a consistent motion is used. The complexity of the system might be outweighed by its benefits, but the true improvement and ease of use is still unknown. While I personally like this design a lot, I do not feel that it is a viable option as the cost of manufacturing compared to the first design is more than tripled.
Fig 4: Singer Sewing Machine Style Fig. 5: Singer Sewing Machine Style
Pump Front View. Pump Back View.
Main Parts of the Pump
The singer sewing machine design consists of a few more parts than the spring
return design. Most importantly, the two flywheels have been added, and a larger
two stage foot pedal. The rest of the linkages are very similar to the first design.
The flywheel would probably be cast iron, since the weight of the flywheel
spinning is what makes half of the pumps motion work. Again, all of these parts
bolt on with little parts to change or replace. This design, as with the previous
design, does not rely on a flat surface for the device to rest on. It gets its support
and strength from the pump and its base flange mounting configuration.
Mode of Operation
This design uses the flywheel as its primary means to sustain a fluid pumping
motion. To get it pumping effectively might take a few tries to get the flywheel
spinning, but once spinning, the system requires very little effort to use. To
operate, the user simply puts force downward on the pedal, and if required, put
weight downward on the lowest most part of the pedal to get the device to return.
The lowest most part of the pedal acts like the spring did on the first design, but is
only required to get the pump moving smoothly. Once the flywheel has gained
some momentum, the user only has to push down on the foot pedal as the pedal
starts to move, sustaining the motion that it already has. Most people could very
easily get the pump working with just a few moments of effort.
Although it may seem like these are not significant improvements on a design that is still operational and working fine, the practicality and benefit that these pumps would have is all too real. While we may not see wide spread distribution or use, the steps have been taken to make some sort of change that would benefit the people using these kinds of pumps everyday. The biggest concern is the cost of manufacturing and the ability to effectively distribute these pumps to those who need them or have a desire for change.
While it is a significant hurdle, many groups and organizations might be willing to look further into the use of these designs and the eventual improvement of the current system. The cost of manufacturing can also be lessened if made within the countries that would use them. Typically, these costs can be decreased to only small percentages of what it would cost in the United States or Europe. All of these factors need to be considered when moving forward with this project. Further research and study needs to go into finding out just how much benefit the new design would give. It would be amazing to see everyone open to a change, but the reality is that a lot of countries and particular villages will want to keep their current pump, being afraid that the new system will not work as good, or will leave them without water.
Current hand operated water pump designs are lacking in many regards. While most pumps work fine in the developing countries that still use them, these pumps have not been improved in nearly a hundred years. The benefit of a new design is obvious, as it would increase the user’s ability to pump for long durations, and would make pumping
for short durations easier and less straining. There are many viable designs that can be used, but it seems that the simpler it is, the better. Anything too complicated is likely to break down and not be serviced, while the people who typically use it would be without drinking water.
This project has been made possible through the support of NCIIA.