Text and Photos Michel Azéma

Centre for Alternative Technology
Machynlleth, Wales

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Centre for Altern. Techno
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The water
Not so simple!
The carriages
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The only modern water operated funicular
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Not so simple!  

Cables and Security
The big drum.

Each car is pulled by its own cable. The two cars are linked by a third cable for the tension. On the photo you can see how the cable of the right car is winded to the drum. On the left you can see the end of the cable fixed on the cylinder of the drum. The cable of the left car is also winded to the left part of the drum but upside down. The end on the left cable is fixed on the hub flange.

The bottom end of the tracks.

Here you can see the third cable which links the two cars for the tension. Between the tracks a screw is used to tight the cable but in fact this cable is not really tighted!
The third cable is an old haulage cable.
Near the pulleys, the two hydraulic jacks which are used to empty the water tank of the cars.

Click to enlarge
Inside of the top station.

On the photo you can see the ends of the rails of the two parallel tracks, between the rails the nozzles of the pipes which bring the water to the cars, in the background the black drum
 

The fourth cable.

The thin cable under the main haulage cables, which winds round 5 small pulleys at the top is the final emergency breaking system. It works as follows:
- Any sharp jolt on this cable causes the emergency brakes under the carriage to apply. These are cam shaped grippers which dig in to the timber baulk
under the steel channel supporting the cable rollers in the centre of the track.
This jolt may be caused by:
1) Failure of the main haulage cable. Very unlikely as the main cables are renewed every two years.
2) Major overspeed. Should the other breaking systems fail and speed increase to twice the design speed of 0.6m per second, the centrifugal governor on the yellow pulleys activates jaws which clamp on to the small cable. This pulls out the torpedo release and the carriage brakes, softened by hydraulic dampers, bring the carriage to a stop in a very short distance.
3) Minor overspeed. Should the main speed control brakes fail and speed increase to 1.8 times the design speed, the centrifugal governor on the yellow pulleys flies out and breaks the electrical supply. This results in all brakes on the drum being applied.

The carriage brakes which are released by the security cable. They are composed of four jaws which squeeze a wooden beam between the rails.

In the foreground, the hydraulic jack which
controls the filling of the water tank of the car.
Not so simple!

Actuator (on the left), oil tank (on the top) and you can see part of one of the four accumulators which compress the nitrogen (bottom right corner).
Once the gate and doors of the carriages are closed the cumulative weights are read by a computer in the top station, using the pull of the cable on the winding drum.
Hidden underneath the front of each carriage is a tank which can contain 1.6 m3 of water. The correct amount of water is allowed through the pipe from the lake into the tank of the top carriage. Then the brake is released and the heavier car begins to move. The speed is measured by the processor counting the gear teeth going by in the gearbox. The processor then tells the electric actuator connected to the control arm of the variable pump what to do. If it is going too fast, the hydraulic pump pumps more oil into the accumulator. Should the carriage being moving too slowly, less is pumped. The pump controls this at the breakness speed of 0.7 m/s!
Should there be considerably more passengers going down, such as during the second half of the day, only a small amount of water is used and the pumping is automatically increased.
The accumulator accumulates energy by letting the oil compress nitogen gas inside a bag. It is often used to drive the hydraulic rams on the 'fills', 'emptys' and brakes etc. When the gas is fully compressed, it is released to drive a hydraulically powered water pump that fetches water from the holding pond beneath the bottom station back up to the lake. This elegant method ensures a little as possible of the energy of the system is wasted! The holding pond also obtains water independently from a stream underneath the hill.
   
Old issues Index
 
Centre for Altern. Techno
Presentation
The water
Not so simple!
The carriages
Technical datas
 
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Michel Azéma, Paris (France)
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