SNCF and the SP2I company have pooled their skills to develop a retractable collection system designed for TGV high-speed trains and TER suburban trains maintenance workshops. This device called "RETRACTABLE CATENARY" has been jointly patented in Europe by SNCF and SP2I. This partnership dates back to 1992, with the building of the north-east Paris maintenance centre in Landy.
To make train roof maintenance operations easier, the retractable catenary helps:
When in collection position:
Take trains in and out of a building using electric power, for traction motor trials, or operations requiring the use of a live contact line.
When in "retracted" position
Carry out operations over the trains, anywhere, using mobile overhead cranes for the whole length of the workshop, cherry pickers... or specific operations such as taring a pantograph. Carry out operations under the train using lifting systems.
The overhead contact line, usually made up of a mechanically tensed, contact wire made from hard copper, is replaced by an aluminium beam supporting, in the lower part, a clipped-in contact wire.
The aluminium beam hangs without mechanical tension above the track on arms equipped with an orientation mechanism. The aluminium beam is attached to a composite flexion insulator, located at the end of the arm, via a sliding suspension brace to allow for the linear travel of the beam due to dilatation.
A blocking bracket is located at the level of the arm closest to the centre of the beam, the dilatation will occur on either sides of this bracket.
To retract the aluminium beam that makes up the catenary, all the arms rotate horizontally, simultaneously and in a synchronised manner.
The catenary is earthed, in the retracted position, on the last arm. This earthing is automatic at the end of the retracting process.