21 March 2014

Anderton Boat Lift, Northwich

The Weaver Navigation was completed in 1734, allowing swift transportation from the Cheshire 'salt towns' to the River Mersey. In 1777 opened the Trent and Mersey Canal, at Anderton close to, but fifty feet above, the navigation, and providing a connection to Stoke-on-Trent. In 1793 a basin was excavated on the north side of the navigation, enabling goods to be trans-shipped by crane and inclined plane. To address significant traffic growth, the engineer Edward Leader Williams designed a lift of two counterbalancing water-filled caissons, supported by interconnected hydraulic rams: additional water need only be added to one caisson for this to descend and its twin to rise, with fine adjustments requiring just a 10hp steam engine.

The hydraulic engineer Edwin Clark undertook the detailed design. The caissons, each 75 feet long, 15.5 feet wide, 9.5 feet deep, and weighing 252 tons when filled, were supported by hydraulic rams - hollow cast iron pistons, 50 feet long and three feet in diameter, inside buried cast iron chambers of the same length but of 5.5 feet diameter. The original superstructure consisted of just seven hollow cast iron columns, to guide the caissons, connecting at the top to a 165 feet long wrought iron aqueduct, gated at each end. The ride took three minutes, although were a caisson raised or lowered independently, using only the power of the steam engine, this extended to 30 minutes. Construction commenced in 1872, and the lift opened in 1875.

Unfortunately, canal water was used as the hydraulic fluid, and the rams corroded badly. The engineer Colonel Saner designed a replacement system of electric motors, wires, counterweights and pulleys to allow each caisson to move independently. The superstructure was strengthened by the addition of steel A-frame buttresses, and 36 cast iron counterweights, of 14 tons each, were installed. The pulleys were driven by a 30hp motor. The conversion work was undertaken between 1906 and 1908.

The lift closed in 1983 due to the discovery of extensive corrosion in the superstructure, but was fully restored between 2000 and 2002. Although the headgear and buttresses of 1906-8 remain in place - the weights form a children's maze nearby - the lift once again operates hydraulically, using oil-filled rams to drive each of the caissons separately. The Anderton and the Falkirk Wheel are the only operational boat lifts in the UK.

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