Crank0 rpm

What this step adds; in part B, water on the moveParts already in placeA rope pump lifts water with a loop of rope carrying plastic pistons up a 32 mm PVC riser; each piston pushes the water above it to the spout, and the rope comes back down outside the pipe. The model takes flow as bore area × rope speed × 85% (an assumed share that does not leak back past the pistons). One turn of the crank turns the 0.5 m tyre wheel once, so 40 turns a minute moves the rope 1.05 m/s and gives 43 L/min, close to the reported ≈ 40 L/min from 10 m by hand. Lifting that 10 m takes 70 W, about 88 W at the handle with an assumed 80% for friction. The 40 L/min and 120 L/min (with a horse) figures, the US$20–120 cost and the ≈ 50,000 pumps in Nicaragua with about 90% still working come from old Akvopedia wiki revisions, which the notes flag as a weaker source. The well is drawn much shorter than 10 m, so the pistons appear closer together than the real ~1 m. This is a guide to how the parts go together, not engineering drawings. Keep the well covered so nothing and no one can fall or wash into it, and keep children away from the turning crank.