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Falkirk Wheel

2007 Schools Wikipedia Selection. Related subjects: Engineering

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   The Falkirk Wheel
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   The Falkirk Wheel

   The Falkirk Wheel, named after the nearby town of Falkirk in central
   Scotland, is a rotating boat lift connecting the Forth and Clyde Canal
   with the Union Canal, which at this point differ by 24 metres, roughly
   equivalent to the height of an eight story building.

   On 24 May 2002, Queen Elizabeth II opened the Falkirk Wheel as part of
   her Golden Jubilee celebrations. The opening had been delayed by a
   month due to flooding caused by vandals who forced open the Wheel's
   gates.

Design of the Falkirk Wheel

   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.
   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 is the only rotating boat lift of its kind in the world, and
   is regarded as an engineering landmark for Scotland. The United Kingdom
   has one other boat lift: the Anderton Boat Lift in Cheshire. The
   Falkirk Wheel is an improvement on the Anderton Boat Lift and makes use
   of the same original principle: two balanced tanks, one going up and
   the other going down.

How the wheel rotates

   The wheel rotates together with the axle which is supported by the 4
   metre diameter slewing bearings which are fitted to the ends of the
   axle and have their outer rings mounted on the plinths which in turn
   are constructed on top of piled foundations.

   The slewing bearing at the machine-room end of the axle has an inner
   ring gear which in this configuration acts as a rotating annulus. The
   rotating annulus is driven by ten hydraulic motors which are assembled
   on a stationary bearing and motor assembly known as the planet carrier
   which in turn is also mounted onto a plinth similar to the one at the
   other end of the axle. The driveshafts of the motors have pinion gears
   which act as stationary planetary gears in this train of gears and
   engage the rotating annulus ring gear. Electric motors drive a
   hydraulic pump which is connected to the hydraulic motor by means of
   hoses and drive the wheel at 1/8 revolution per minute

Construction of the wheel

   The wheel was constructed by Butterley Engineering at Ripley in
   Derbyshire under Millennium Plans to reconnect the Forth and Clyde
   Canal with the Union Canal, mainly for recreational use. The two canals
   were previously connected by a series of 11 locks, but by the 1930s
   these had fallen into disuse, were filled in and the land built upon.

   The Millennium Commission decided to regenerate the canals of central
   Scotland to connect Glasgow with Edinburgh once more. Designs were
   submitted for a lock to link the canals, with the Falkirk Wheel design
   winning. As with many Millennium Commission projects the site includes
   a visitors' centre containing a shop, café and exhibition centre.
   The Falkirk Wheel in action. The wedge-shaped building on the right is
   the visitors' centre. Click on image to view the Docking Pit at the
   bottom canal.
   Enlarge
   The Falkirk Wheel in action. The wedge-shaped building on the right is
   the visitors' centre. Click on image to view the Docking Pit at the
   bottom canal.

How the caissons are kept level

   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 caisons stable and perfectly
   level.

The dry well

   The dry well is a drydock-like port that is isolated from the lower
   canal basin and kept dry by means of water pumps. If it were not for
   inclusion of the docking-pit the caissons and extremities of the arms
   of the wheel would be immersed in the lower canal basin each time the
   wheel rotates. This would result in a number of undesirable situations
   developing, such as providing buoyancy to the bottom caisson and the
   viscosity of the water causing an increase in the required power.

How the canal was routed through the wheel

   The route chosen to take the Union Canal to the site of the wheel
   involved building a completely new section of canal, leading from the
   original terminus at Port Maxwell to link up with a new basin to the
   south of the wheel. The water level in this basin is the same as the
   top section of the wheel, with a 150 metre tunnel joining the two.
   There are two locks to drop the canal level from that of the Union
   Canal to this basin. The tunnel was required because the canal had to
   pass underneath the route of the Antonine Wall without disturbing its
   archeological remains. Just at this point the canal also passes below a
   road and the main Edinburgh to Glasgow railway line.

Costs and prices

   The Falkirk Wheel cost £17.5 million, and the restoration project as a
   whole cost £84.5 million (of which £32 million came from National
   Lottery funds). As of 2006, a ride on the Wheel costs £8 for adults and
   £4.25 for children aged 3-15 (free for children under 3), OAP
   concession £6.50, student/UB40 concession £6.50 and family price of
   £21.50 (2 adults and 2 children) with a discount of 10% for a group of
   20 or more.

Future rotating boat-lifts

   A similar design of boat-lift has been suggested for a proposed new
   canal that would run along Marston Vale in Bedfordshire, as part of a
   large-scale project creating an area of leisure and tourism facilities
   linked to the future expansion of Bedford and Milton Keynes. The canal
   would link the Grand Union Canal at Milton Keynes with the River Great
   Ouse at Bedford.

Photographs

   Retrieved from " http://en.wikipedia.org/wiki/Falkirk_Wheel"
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