The Montech water slope is a type of canal inclined plane built on the Canal de Garonne, in the commune of Montech, Tarn-et-Garonne, South West France. It is managed by the publicly-owned Voies navigables de France and it replaced a group of five successive locks.
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The principle of the water slope is based on a sloping channel up or down which a wedge of water retained by a water tight gate is moved. This technique was invented in the 19th century by the German engineer Julius Greve and described by the French engineer Jean Aubert [1] in 1961.[2][3] The Montech water slope was inaugurated in July 1974.
A sloping concrete channel is continuously fed by a small stream of water. A movable gate spans the channel. The points of contact of the gate with the channel are tight but not fixed. Two adapted diesel locomotives, one on either side of the channel support the gate.
To allow a boat to ascend: the gate is lifted, the boat enters the channel, and then the gate is lowered. This isolates the wedge of water, on which the boat is floating, from the canal it has left. The locomotives ascend the slope pushing the water wedge in front of the movable gate. The boat rides on the water wedge.
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By its power and ingenuity the slope engine is the key to the system. It consists of:
Each diesel electric locomotive develops 1,000 horsepower (750 kW) distributed to four drive motors, one on each of the four axles each with two large pneumatic tyres.
The three contact faces of the gate with the channel are equipped with seals to keep the wedge of water in place. The gate is raised or lowered using a hydraulic ram.
The shock absorber is a hydraulically-levelled hinged metal frame. It allows boats to be moored to the gate during ascents and descents. An electronic system keeps motion gentle and smooth. Finally triple brakes slow the system without jerks.
The water slope allows the five locks it replaced to be bypassed. These locks are still in use, mainly to allow the passage of pleasure boats. The water slope is reserved for boats 30 to 40m in length and ascends or descends in 20 minutes, 45 minutes faster than the passage of the five locks.