Morris Dovey wrote:
MikeWhy wrote:

Locking against heavy loading would seem to suggest a worm. PV? A
Stirling pumped "hydraulic" motor/water wheel? I know... complexity.

PV plus motor plus worm drive is certainly an attractive route, but
too expensive and not suited for local production and maintenance.

It needs to be really simple and so inexpensive that it's not worth
stealing. For context, rural Somalia might be one of the target
"market" areas.

Offhand I'm not sure how one would design such a thing but rather than using
shaft work could you pump water from one plastic bag to another, with
appropriate levers and paddles resting on top of the bags?