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Vehicle description:
Since 1996 JLS has been supplying the Prague Metro with fully upgraded 797.8 class locomotives designed for light shunting and transportation of light service trains on the underground rail network. From the original 700–702 class locomotive only the bogie assembly has been used, i.e. the underframe inclusive of axles with gearboxes. All other parts have been newly designed and made.
The driver’s cab, with large windows, negatively sloped front windshields, side doors and superb visibility, has been constructed to fit the metro track gauge. There are two diagonally located control desks in the cab. A new Liaz M1.2C M640 is mounted in the front hood, flange-coupled to a Siemens Drásov 1FC2 284 traction alternator. Via a rectifier the alternator powers one TE 005 traction motor mounted longitudinally in the rear hood driving a new mechanical gearbox via a cardan shaft.
The original cardan shafts and axle gearboxes are then used to drive the axles. The locomotive is fitted with a DAKO brake with electronic controllers for the automatic and direct-acting brake. The mechanical part of the brake is newly manufactured. To increase the braking efficiency on the large gradients in the metro, each wheel has its own brake cylinder. The compressed air source is two compressors (a 3 DSK 75 and a 4133 on the engine). The locomotive is fitted with master-slave control, including the option of controlling the brake systems of the new metro trains. The buffer beam has been modified for coupling via a traditional screw coupling; an automatic metro coupler or coupling gear for railway cars can be installed as required. To date, seventeen 797 locomotives have been supplied, with inventory numbers of 801 and above.
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