OT but someone here might know

[Bob Minchin]

Years ago, there was a prototype electrical generator shown on TV - possibly Tomorrow's World etc.

It was a low ramp on which one wheel of a vehicle was driven and parked. In the ramp was a pair of rollers driving a generator. The other vehicle wheels were chocked. With the car in gear and at tickover speeds a useful amount of power was generated. I seem to recall the demonstration was a farmer going out to repair a gateway and being able to run an electric drill to assist the repair.

Does anyone know if this was ever taken to a commercial product and have any references to it?

I have an application where something like this would be a possible solution.

Thanks in Advance

Bob

[The Natural Philosopher]

its not hard to build..

[Harry Bloomfield]

Bob Minchin formulated the question :

I can remember it vaguely.

I've not seen anything, probably it wasn't that practical.

Likely the same could be achieved using an additional alternator, under the bonnet. Or there are plenty of small portable genny sets about now, for not much money.

I'm listening?

[Jules]

I wonder if the original commercial product was canned over H+S worries... must be fun if someone got stuck in the rollers, or chocks came loose, or something in the mechanism fouled up. Not something a DIYer has to worry about (well they do, but if something screws up it's their own fault) but I could see it having some commercial issues...

I like the 'build one' aspect - but where does one source a big-ish alternator these days? Make one? (i.e. same sort of DIY disk alternator that some of the wind tubine homebrewers are cooking up) - or is there a good source somewhere for alternators without any kind of engine to drive them?

cheers

Jules

[Bob Minchin]

My requirement is not to generate electricity but to directly drive a pump to extract water from a well in deepest France where one could drive a standard 2CV van. The important part of my requirement is the vehicle is unmodified and the drive is taken from a driven wheel. Bob

[Dave Plowman (News)]

These days most car alternators produce a lot of amps - so an inverter would be a cheaper solution. And more efficient. Most modern cars will alter the idle speed to cope with the extra load.

[Harry Bloomfield]

A basic car alternator can produce 110v.

[Harry Bloomfield]

It happens that Dave Plowman (News) formulated :

The well would likely need to have the pump lowered down into it, because most efficient types of pumps are not able to create enough vacuum to draw the water up to them - so the electrical, rather than a direct mechanical solution is more likely to work.

Get an inverter and a sump pump.

[Andrew Gabriel]

Let's see... Using drill... bit jams... heavy load on generator... large resistance on rollers... car comes bouncing off and drives itself off into the distance...

[The Medway Handyman]

Sounds like an extremly simple & practical idea - along the lines of the wind up radio. Possibilities are endless, hook up a hydralic pump instead of an alternator & the world is your lobster.

I wonder why it never made it? Prolly too simple & practical. Most of the Third World would love the idea.

[Jules]

Ours is 80' deep or so, with the pump at the top, but it needs to be primed with water before it'll work (i.e. a well in the bore-hole sense, rather than wide brickwork medieval shaft).

I've never had to prime it myself, so I'm not sure exactly how much water it needs - although the folks next door have a similar setup and said that they once primed theirs with "a few" buckets full of water from the next folk down, so it can't typically be *that* much (i.e. so if that's what the OP has then it'd be possible to transportable enough priming water to the site via a vehicle)

One day I might read the manual to see exactly how it all works ;-) There's two pipes, so I assume forcing water down to the well base somehow pressurises things and forces more water up the main bore to the top, so some such voodoo.

cheers

Jules

[Dave Plowman (News)]

Still cheaper to use an inverter with most vehicles. You then have the choice of cheap mass produced mains devices.

It sounds like a horribly inefficient way of using fuel and resources. In a 'third world' country a vehicle with a power take off would make more sense.

[Jules]

How well do they cope with big inductive loads such as motors though, where the start-up surge can be quite big? (i.e. the well pump that the OP refers to)

I agree it seems like a good solution if running everyday electronics out in the wilds, I just don't know how well it'd stand up to running the 'bigger stuff'.

On the negative side, there are inefficiencies in running a generator via rollers from a car wheel I suppose - but on the plus side, any vehicle can be used rather than needing one with a PTO (and in any kind of harsh environment, the less single points of failure the better)

cheers

Jules

[dennis]

The pump can't be at the top, you can only raise water by 32 feet using a vacuum. The pump must be at the bottom where it can apply pressure to raise the water by more than 32 feet.

Maybe you inflate a bladder at the bottom and force the water up?

[Owain]

Or a horse mill or 'Persian well'. Powered by humans if there aren't any other animals.

Owain

[Dave Plowman (News)]

In the same way as your generator driven off the car wheel would - it needs to be butch enough to cope with a starting load.

You need one rated for the job.

Friction drives are horribly inefficient - as well as the safety issues.

[Jules]

OK... I was just curious as most inverters I've seen are piddly little things which seem like they'd happily go bang if given any serious work to do :-) (but fine for running laptops etc.)

No argument there! In the OP's case I'd be looking at something* other than a roller drive. But some somewhere where keeping things running is more important than the efficiency or safety, I can imagine it might make a good minimum-maintenance solution.

• going IC engine -> roller drive -> alternator -> motor -> pump does seem a bit clunky. Even jacking up one back wheel of the vehicle and tapping mechanical power straight from there to drive the pump might be relatively painless (given enough hub bolts on the wheel it might just be a case of removing two or three and bolting a drive flange to them - no need to even take a whole wheel off). There's still the inefficiency of the vehicle's drivetrain, but OTOH it allows better matching of engine and pump speed.

cheers

Jules

[Jules]

It's at the top; surface-level pumps are very common out here. The following seems to explain operation pretty well:

(watch for URL wrapping)

Priming seems to be limited to just filling the surface-level pump, so they don't need a lot of priming water at all (subject to the anti-drain valve in the shaft operating properly)

We've actually got a separate (abandoned) well shaft out back; a pit of at least 20' deep with square cross-section (sides about 3' wide) - I suspect that did once house a submerged pump (or at least something operating on vacuum and not raising water very far). It's so full of junk right now that I'm not sure how far down it goes :-)

cheers

Jules

[BigWallop]

Wouldn't it be easier to buy a 12Vdc appliance and plug it into the cigar lighter socket. There are huge amounts of things that have been specially designed to run like that.

[nightjar]

Why the last? It is usually more efficient to pump up, rather than to lift by suction, so I would drop a 12 volt submersible pump, like a boat bilge pump, down the well and run that from the car battery with the engine running..

Colin Bignell