the 1996 Stock used on the Jubilee line. Both trains use the same bodyshell design, and were built at the same factory at the same time. However, there are some major differences, mostly relating to the mechanical and electrical equipment. The main technical differences arose as 1996 Stock was designed for "cheapest contract cost", while 1995 Stock was designed for "life cycle cost", given Alstom's long term interest in reliability due to their PFI maintenance contract. The most noticeable difference is the type of traction motor used. The 1996 Stock design specification was "frozen" in 1991, meaning that despite the name, the 1995 Stock actually uses more modern equipment. The 1995 stock uses Alstom's "Onix" three-phase insulated-gate bipolar transistor (IGBT) drive, whereas the 1996 stock uses three-phase induction motors fed from a single-source inverter using a gate turn-off thyristor (GTO), derived from those on / Networker trains. This means that, unlike the 1996 Stock, the 1995 Stock does not make the same "gear changing" noise when accelerating from rest. Another major difference is the type of bogie used. The 1995 stock uses Adtranz bogies with air suspension to cope with the difficult track conditions of the more extensive underground sections of the Northern line, whereas the 1996 stock uses Alstom bogies with rubber suspensions. Other differences include tip-up seats in the middle of each coach, instead of perch seats on the 1996 stock, as well the use of orange LEDs for the passenger information displays, as opposed to the red LEDs used on the 1996 stock. Each train is made up of two three-car units, coupled together, with each unit consisting of a Driving Motor car (DM), a Trailer car (T) and an Uncoupling Non-Driving Motor car (UNDM). The six-car trains are therefore formed DM-T-UNDM+UNDM-T-DM. Some trailer cars are fitted with a de-icing tank and applicators, in order to spray de-icing fluid on the conductor rails along above-ground sections of track; these cars are marked by a small circle after their car number. The 1995 Stock is the only deep-level tube stock to use selective door operation, necessitated by short platforms at stations such as , , and . Maintenance Alstom is responsible for maintaining the trains under a PFI contract which runs until 2033. The main depot is at Golders Green, with another large depot at Morden, and two smaller depots at Highgate and Edgware. Diagram (Non-Refurbished) See also