Instructables
video Rope Pump (Elephant Pump)

We are team el Elefante and this is our submission for Hydro Do That..., a team project in our second year of Product Design Engineering at Glasgow School of Art. The brief was to raise 5 litres of water 600mm in the most efficient way possible. Supplied with a 24V motor, it was up to each team to design and build a pump over a 6 week period. A rope pump (or elephant pump) works by passing a loop of stoppers through a pipe. Each stopper lifts a section of water; once running at a high enough speed, the flow of water is quite smooth.

The Rope Pump is built using a length of 22mm copper pipe with a 28mm section attached to the top as a reservoir to prevent overspill. A funnel is attached to the bottom to help feed the rubber stoppers into the pipe. For the loop of stoppers, we sourced some rubber furniture feet that fit in the pipe with 1mm clearance. For increased efficiency, as small a clearance between the stoppers and the pipe is required - whilst still minimizing friction.

The drive wheel is made of MDF, although we would recommend a more waterproof material. It has a diameter of 120mm and has flared edges to help grip the rubber stoppers. Beneath the water is a small plastic wheel that is free to rotate and is there only to maintain tension in the nylon rope and guide the stoppers.

We sourced a gearbox from RS Components, using several 4:1 gear drops and controlling our input voltage to achieve the desired speed. A small metal base was added to one of the gears as it was slipping when we ran the pump. (This can be seen half way through the video, attached to the green gear.)

The video you see here is not the final event in which we competed against the other teams, it is just one of our final tests.

Out of the six teams that ran this project, our team was the most efficient (11% compared to second place 3% and third place 0.01%) We ran the pump at 18V, achieving the 5 litres of water in just over 33 seconds.
lucpet3 months ago

I've never seen anything like this and was wondering just how long something like this could run without a "wearing" breakdown. Is this type of design a common thing used in industry as I'd imagine it would have longevity in that case.

gwylan3 years ago
Very cool! I plan on building a rope pump for my well this summer. What did you use for the stoppers?
Depends on the size of pipe. Try anything that is mostly water proof. Corks, pingpong balls, soft rubber balls, wadded up paper bags, round pieces of leather (put a washer a little smaller than the pipe under the leather, and have the leather be a little over size so it will 'wipe the walls') ... go shopping at your local $ store and be imaginative!

First get it working, ... then optimize. :)
tulekah3 years ago
in "de re metallica" their are a number of rope and chain pumps for draining mines. most use large rag balls that compress when pulled into the pipe making a reasonable seal.
junits153 years ago
Am I the only one that heard Katy Perry's ET in the background? :P
me too
same
just wondering why is you picture a CPU cooler?
Because I'm weird. I just built my computer recently and am obsessed with it, so I put that as my picture... Like I said, I'm weird.
aight ill accept that answer
Very nice! Did you try varying the length of rope between each stopper? It seems like the maximum value would be equal to the length of the pipe that extends beneath the surface of the water, but I´m guessing greater efficiency would be achieved with a length somewhat shorter than that. Also, did you have some sort of flare or funnel at the bottom of the pipe?

Congrats on winning your competition.
SamBurrowes (author)  Sam the Wizer3 years ago
We tried a few different lengths between the stoppers; you're right, the maximum is the length between the surface of the water and the base of the pipe. For us, it was approx. 60mm. And yes, there is a simple plastic funnel on the bottom of the pipe to help feed the stoppers in.

And thanks! :)
Housedog3 years ago
Neat concept. Not much of an "Instructable" though, is it. Kinda like what Redneck said.
Very nice! Did you try varying the length of rope between each stopper? It seems like the maximum value would be equal to the length of the pipe that extends beneath the surface of the water, but I´m guessing greater efficiency would be achieved with a length somewhat shorter than that. Also, did you have some sort of flare or funnel at the bottom of the pipe?

Congrats on winning your competition.
XOIIO3 years ago
Brilliant, combined with a coke can stirling engine it would be epic.
Handy_Andy3 years ago
Very nicely done! {hurries off to go find a need to build one}
interesting, all though couldn't you have used just thick knots instead off the stoppers, matching the pipe i.d. to the knots o.d. ?
SamBurrowes (author)  iminthebathroom3 years ago
You're exactly right, it was a considered solution. I believe that technique is used in wells that use this style of pump. We just wanted to have a more sophisticated design, seeing as we were being graded on this project. Another solution could be leather disks, they would ensure a very tight fit.
gotcha, besides your pump works and looks awesome!
Interesting. Now could you show some pics from differant angles and parts so if I wanted to make one myself I'd have a better understanding of how you got it hooked up?
SamBurrowes (author) 3 years ago
We actually used the small rubber 'feet' you can get for tables and chairs. Not too sure how good they would be for outdoor use though!