A good use of Acrhimedes Principle

[SloopJohnB 322]

http://www.falkirk-wheel.com/

 

Who has been there?

 

It takes just 22.5 kilowatts (kW) to power the electric motors, which consume just 1.5 kilowatt-hours (kWh) of energy in four minutes, roughly the same as boiling eight kettles of water.

 

The wheel, which has an overall diameter of 35 metres, consists of two opposing arms which extend 15 metres beyond the central axle, and which take the shape of a Celtic-inspired, double-headed axe. Two sets of these axe-shaped arms are attached about 25 metres apart to a 3.5 metre diameter axle. Two diametrically opposed water-filled caissons, each with a capacity of 80,000 gallons (302 tons), are fitted between the ends of the arms.

These caissons always weigh the same whether or not they are carrying their combined capacity of 600 tonnes of floating canal barges as, according to Archimedes' principle, floating objects displace their own weight in water, so when the boat enters, the amount of water that leaves the caisson is exactly the same as the weight of the boat. This keeps the wheel balanced and so, despite its enormous mass, it rotates through 180° in less than four minutes while using very little power.

 

The caissons need to rotate at the same speed as the wheel but in the opposite direction to keep them level and to ensure that the load of boats and water does not drop out when the wheel turns.

 

The end of each of the caissons is supported on small wheels which run on the inside face of the eight metre diameter holes at the end of the arms, enabling the caissons to rotate freely.

 

The rotation is achieved by means of a train of gears comprising three eight metre diameter ring gears with external teeth and another two small jockey gears. One of the large gears acts as a stationary sun gear and is fitted loosely over the axle at the machine-room end of the axle and fixed to a plinth to prevent it from rotating. The two small jockey gears, the outer rings of bearings, are fixed to each of the arms of the wheel at the machine-room end of the wheel and act as planet gears. When the motors rotate the wheel the arms swing and planet gears engage the sun gear which results in the planet gears rotating at a higher speed than the wheel but in the same direction as the wheel. The planet gears engage the large ring gears at the end of the caissons causing them to rotate at the same speed as the wheel but in an opposite direction. This keeps the caissons stable and perfectly level

[wheels 543]

I can't remember where I cam across this thing before, but it is truely awesome.

[w44vi 17]

I think discovery channel had a piece on this it is fantastic

[Bimini Babe 0]

I did visit it once and remember being particularly underawed by it. Perhaps I just don't get it... Nice shot though - does it way more justice than the obligatory visitor centre, which is situated nearly directly underneath the wheel, hence gives no real sense of scale.

[Guest]

I love this thing. Underawed BB? You probably don't get it. However the principle do so damn simple, perhaps you just wondered why nobody had done it before. Seems to me they could dispense with the electricity altogether and use a crank handle or something.

[Guest]

I wonder how they seal off the top canal while the wheel's going around.

[Bimini Babe 0]

Actually I do remember wondering if a canal boat was suddenly going to be propelled overhead off the end of the aquaduct! Now THAT would be impressive.

[Guest]

The docking-pit is a drydock-like port which is isolated from the lower canal basin by means of watertight gates and kept dry by means of water pumps.

[johnMi 2]

 

all they would need to move the wheel would be to remove the amount of water from the lower 'lock' to overcome the friction, and it would automatically stop at the top.

[Guest]

Yep, just give it little push.

[Kiwi303 0]

To be accurate, it's not an Archimedes Screw... A grain auger is an archimedes screw, that thing is just a ferris wheel on steroids. A very big ferris wheel with a very impressive steroid habit, but still not an archimedes screw.

 

Or are you talking about his displacement theory as used to balance the two dippers?

[wheels 543]

To be accurate, it's not an Archimedes Screw..

No not the screw, but the principle of displacment. That "eureka" moment.