ČKD T-669 diesel locomotive

T-669.0 (770) class diesel locomotives, built by ČKD are six-axle, with two bogies. The wheel pairs are set in radius arms and have a simple coil spring suspension. The body is mounted on the frame with eight anchors. The locomotive is a hood unit type with an internal, eccentrically positioned operator's cab.

Machinery
Located underneath the front hood is the traction assembly – a K 6 S 310 DR diesel engine and a TD 802 traction generator – and auxiliary machinery powered by the diesel engine via a hydrodynamic transmission. Chillers and ventilators are located here as well. TE 006 traction motors are axle-mounted on the wheel sets. Located underneath the rear hood are batteries and a supply of sand.

Variations
After modifications of the seating of the hood on the frame, the T 669.1 (771) and the wide-gauge version T 669.5 (770.8) were created at SMZ Dubnica.

Users
This class of locomotive, manufactured for Czechoslovak State Railways, Soviet Railways, and railways in Poland, Albania, India, Iraq and Syria numbers over 8,000 units, making it the largest series of locomotives ever manufactured in Czechoslovakia.