Trip in caisson
Lifts for passenger and goods transports? Commonplace. Car lifts? Used to reach parking spaces in parking garages and residential blocks. And ships?
With locks canals can be overcome by a few metres. If the height difference is great, you need a ship lift like the one in Niederfinow on the Havel-Oder Canal north-east of Berlin.
14,000 ton steel structure
When the Havel-Oder Canal went into operation as “Hohenzollern Canal” in 1914, it was a technical challenge to compensate a terrain difference of 36 m at Niederfinow. A flight of locks or ship lift was to be created; the flight of locks was built first. After the First World War, there were further investigations until the Academy of Building approved a draft of the national transport ministry for a ship lift, which went into operation in March 1934.
The ship lift consists of a 14,000 ton steel structure, held together by five million rivets, which is 60 m high, 94 m long and 27 m wide. On top of this, there is the likewise riveted 157 m long bridge, made of 4,000 tons of steel and which connects the lift with the upper canal.
The foundation is impressive too: the nine reinforced concrete pillars were driven 22 m into the ground by compressed air to reach load-bearing soil layers. The bottom slab is 111 m long, 34 m wide and 8 m thick.
Cassion as centerpiece
The centrepiece of the lift is the caisson, the moveable part of the structure in which the ships are raised and lowered. The caisson, which is closed on both sides by lift gates, weighs 4,300 tons when filled. The weight does not change when a ship moves in or out – just as much water flows in or out as the ship weighs.
The caisson is suspended on 192 steel cables guided over 3.5 m diameter sheaves, which are in the halls of the top floor. At their ends the cables have counterweights that compensate the weight of the caisson. Four cogwheels running up and down cogged ladders provide for movement and are driven by 55 kW d.c. motors.
The height difference is overcome in five minutes. This corresponds to an average travel speed of 12 cm/s, which is reached after a metre of caisson travel or 20 seconds. A ship needs about 20 minutes for passage including the entry and exit manoeuvres.