753 (T 478.3) Class Locomotive

Origin and Description

T478.3

In the second half of the 1960s, T 478.1 (751) class locomotives replaced medium-power steam locomotives in both passenger and freight transport, but high-power steam locomotives of predominantly pre-war provenance, primarily of the 378.0, 475,1, 476.0, 477.0 classes, required replacement by higher-powered motor locomotives, and in some cases also higher speed. Not even the development and ordering of T 478.3 (753) class locomotives with steam heating and later also the T 478.4 (754) with electrical wagon heating fully replaced the most powerful of them, but for the majority of motorized routes were sufficient for passenger transport. The first two prototypes of the 753 class locomotive was manufactured in CKD Praha in 1968, and after extensive testing, Czechoslovak State Railways bought them in 1970. A test series with a number of modifications, primarily in the traction system, was delivered at the cusp of 1970/71, and production took place from 1972 to 1977. The locomotives were intended for express passenger trains on motorized routes. The locomotive's design is based on the arrangement of locomotive 751; it is of cab unit type construction with newly shaped end cabs. A fundamental change is the diesel motor. After long and difficult development, the 753 class locomotive was the time the K 12 V 230 DR motor with 1325 kW output was used. Power transfer is again electrical (DC), using the TD 802 E traction generator and TE 005 traction motors. The PG 500 steam generator is intended for wagon heating. The locomotive's undercarriage consists of two double-axle bogies of CKD design, with wheel sets set in radial arms and with simple coil spring suspension. The body is mounted on the bogie frames via eight anchors. By increasing the motor's power output to 1460 kW and addition of a heating alternator, another developmental model was created T 478.04 (754) class locomotives, supplied five years later. In light of the shortage of 754 class locomotives, 753 class locomotives are being refurbished with electrical heating in place of the steam generator. They are designated as 750, with the original inventory numbers being preserved.

The new locomotives had a very elegant colour scheme. The upper part of the body was dark green (wagon green), and the lower part of the body dove grey. The locomotive's frame, equipment below it and the undercarriage were grey (dark grey). Bumpers and couplers were black, cow-catchers were vertically striped black & white. Window and headlight frames were lined with white, and interior surfaces of frames were black. Series production locomotives had the frame and undercarriage blue-grey, and starting with No. 128 (as well as Nos. 089, 090, 118 and 119) the hood including the roof were cherry red. The window and headlight frames remained white. Starting with locomotive T 428.3256, the frame was grey.

Basic Specifications

Original SD series designation T478.3
Current series designation 753
Manufacturer KD Praha
Delivery start 1968
Number produced for SD 408
Number in D fleet 259
Wheel arrangement BB
Drive wheel diameter 1000 mm
Bumper-to-bumper length 16540 mm
Gauge 1435 mm
Continuous output 1325 kW
Maximum speed 100 km/h
Service weight 73 t
Number of traction assemblies 1
Power transfer electrical
layout drawing
layout drawing