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Vehicle description:
The 709.7 class is a new generation heavy shunting locomotive based on the earlier successful locomotives of this type made at ČKD Praha. The first locomotive of this class – inventory no. 709.701-7 – was produced by a consortium of locomotive manufacturers consisting of ČKD-DS and ČMKS-JLS. The design of the bogie assembly of the 709.7 class locomotive is taken from the 709.5 class, while the cab and hood design is based on the standard ČMKS kit. Unlike its predecessors, the locomotive is equipped with a Caterpillar engine.
The 709.7 class is a cab-behind-engine locomotive with a turret cab (taken from the 724 class) with diagonal driver’s posts and forward-sloping front windshields. The locomotive’s bogie assembly comprises the underframe and two wheelsets with TE 019 traction motors mounted on the axle with the aid of SKF roller bearings. The wheelsets are guided by swinging arms. The bilateral mechanical brake has a separate lever assembly and brake cylinder with integral slack adjuster and spring brake for each wheel.
The underframe buffer beams are equipped with crumple zones behind the buffers. A Caterpillar 3406 DI-TA diesel engine is mounted in the front hood, flange-coupled to a ČKD Trakce TA 612 traction alternator, which powers the traction motors via a rectifier. The engine water is cooled by an original Caterpillar radiator mounted at the forward end of the front hood. The air source is a 3 DSK 100 compressor driven by V-belts. The rear hood contains an integrated air brake equipment block. Located directly behind the cab is the switchboard and the electrodynamic brake (EDB) resistor. The MORIS digital control system was supplied by NES Dubnica nad Váhom; the brake is a DAKO-GP system with a BSE panel brake valve and electronic controllers for the automatic and direct-acting brake. The 530 kW EDB has inclination/gradient and stopping modes.
The prototype 709.701-7 locomotive was unveiled at an international engineering fair in Brno in 1999. This locomotive is currently in trial operation. A version of the 709.7 class locomotive with a lower axle weight is also in the production pipeline.
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