How to Build a Bicycle Powered Water Pump

Build a bicycle powered water pump. There are many versions of bicycle powered pumps, but this one is probably one of the most simple to put together. You will not need to take apart a cylinder, make a shaft pump or worry too much about seals and valves. This pump is a classic centrifugal design and works from a modified cooling system pump available at any auto store.

Things You'll Need

  • Bike
  • Extra steel sprocket (for the pump)
  • 4 flat metal washers ¼-inch thick
  • Centrifugal water pump with bolts (with two pipes and otherwise closed)
  • Plywood
  • Zip ties
  • 2-by-4 board
  • Deck screws (3½ inches long)
  • Drill
  • Welding equipment
  • Garden hose
  • Hose clamps
  • Optional: steel pipe adapter (piece of pipe that has different sizes at each end)
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Instructions

    • 1

      Get a centrifugal water pump. To find the cheapest of these that is big enough for a home or small-scale gardener, buy a water pump from an automotive supply store such as those used in car cooling systems. Look for a small water pump that has a flat disk on the end of the pump's axle.

    • 2

      Take a steel sprocket (gear) off an old bicycle. Obtain four flat metal washers (¼-inch thick and a smaller diameter than the sprocket). These washers will serve as spacers for the sprocket so the chain has room to overlap on the side. Weld the spacers on one side of the sprocket so that they are evenly spaced near the edge. When you weld the washers, do not let the washers interfere with the area where the chain will attach (1/3-inch clearance from the sprocket teeth).

    • 3

      Center the sprocket on the disk built into the end of the axle of the water pump. Weld the washers (already attached to the sprocket) onto the disk of the Chevy-style water pump.

    • 4

      Disconnect the bike chain from the bike where the pump will be mounted.

    • 5

      Cut the wooden frame to mount the water pump by outlining (as a silhouette) the water pump on a piece of plywood. Trace the bolt holes in the water pump. Remove the water pump from the plywood and use a skill saw to cut out the silhouette shape. Drill out the holes for the bolts. Bolt the pump to the wooden frame with the flat side of the pump against the board.

    • 6

      Remove the rear tire. Hold the mounted pump on the side of the bike where the chain is mounted and loop the bike chain over the sprocket on the pump as well as the sprocket at the pedal if it has come loose. Hold the plywood frame across both the rear stay of the bike and the chain stay so it crosses both in an area that is 2 inches long where they both meet. The stays are the thinner parts of the bike frame that go from the pedal and seat areas to the rear axle. Position the pump so that the sprocket is tight in the bicycle chain. Trace both stays on the wood in this position. Remove the pump from the mount and drill pairs of holes (wide enough to fit zip ties) across from each other that straddle the outline of the stays. Make at least 12 evenly spaced holes.

    • 7

      Bolt the pump back on the wooden plate. Slip the chain on the sprocket at the pedal and the pump. Use zip ties through the holes drilled in step 6 to tightly attach the wooden plate to the bike across the stays. Check the tightness of the chain one more time.

    • 8

      Make a hose adapter (optional) so that the garden hose will attach to the pump. Make this from a steel pipe adapter that fits inside the hose at one end and the pump at the other. Weld this piece in place. Use a hose clamp to secure the garden hose over this part of the adapter.

    • 9

      Suspend the rear of the bike by screwing two boards together to make a T shape. Make the two boards that will be the T shape from 3-foot-long 2-by-4s cut from one piece purchased at the lumber yard.

    • 10

      Find the proper angle of the bike by lifting the rear of the bike to the desired height. Invert the T shape so that the top of the T is along the ground. Lay the leg of the T shape parallel to the rear stay, still holding the bike up. Mark the position of the rear stay. Cut away part of the wood so the rear hub rests on it. Attach the stay to the bike with pipe clamps.

    • 11

      Insert the hose that leads to the center of the pump into a water source. Use a water source that is nonpressurized and start pedaling. The pressure builds inside the centrifugal pump and the water comes out of the pump at the hole in the case at the outer circumference. If desired, a hose can be attached at this point or the hole is aimed at a "pool" near the start of your irrigation ditch.

Tips & Warnings

  • Make sure that the pump you buy has two connectors for hoses, and make sure that you completely close the chamber that usually goes against the engine housing, since this side is usually open. Cut extra layers of plywood to accommodate parts from the inner axle, if needed. Using water-resistant glue, just glue another layer of plywood flat against the layer that you have to make the board thicker. Next, hollow out the area for the axle to spin freely. This step may not be necessary, depending on your pump.

  • Get help welding cast metal if there are any parts that are made with casting because of the difficulty and skill required. Sometimes cast metal will crack if it isn't heated slowly and evenly. Do not use a dirty water pump. Buy yours new.

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