DMU 7021

Six deluxe French diesel-electric units of the class 7021 (JZ 610/617), manufactured by Brissonneau et Lotz Co. of France (ex-GEC Alsthom, today Alstom) were destined for inter-city transport with less standing place and top comfort features (air-conditioning, bar, TV). The five-part unit consists of two motor wagons, two trailers, and one wagon with bar in the middle of the train. Each of the two motor wagons is equipped with a diesel-motor, which can be operated separately or simultaneously, when needed.

Train arrangement	Bo'Bo' + 2'2' + 2'2' + Bo'Bo'; after the modification: 2'Bo + Bo'2' + 2'2' + 2'Bo' + Bo'2'
Years of construction	1970—1972
Manufacturer	Brissonneau et Lotz, France
Received into traffic	1973/02/01
Power of the train	1472 kW / 2002 hp; after the modification: 1786 kW / 2429 hp
Max. speed	120 km/h
Wheel diameter	970 mm
Weight of the train	250 t
Axle pressure	15.7 t / 10.7 t / 11.7 t
Overall length including buffers	127000 mm
Cabs	2

Diesel motors	2 x SACM MGO V12 BSH (772 kW / 1050 hp)
Supplementary motors	After the modification: 2 x 157 kW / 213 hp
Alternator	BL S 12 450 A 695 kVA, 935 A, 535 V
Auxiliary generator	70 kW, 380/220 V
Dynamo	BL EVR 83 BGG 21 AS (10.1 kW, 280 A, 44 V)
Electric traction motor	BL TD 4280 S (153 kW, 285 A, 580/540 V)
Compressor	Westinghouse 243 VB

The first extra repairs of the French DMU-s began on 1973/03/31, including repairs of the air-conditioning system, replacement of single traction motors, MGO diesel-motors and the replacement of bogies. A first major overhaul occured with the collided motor-wagon 610-005. After the seriously damaged front side was repaired, the wagon was restored to traffic by 1974/07/12. The DMU-s of the 610/617 series have been regularly received for examination and repairs since 1974. In 1978, Zagreb Railway Works, in co-operation with Traction Dept. of Zagreb, made all the necessary preparations for dismantling of all the diesel-motor trains of the 610/617 class. The overhauls which comprised some minor modifications were performed from 1983 till 1985. However, failures still occurred. The troubles with electric traction motors and diesel-motors persisted. Therefore, some modifications were suggested in 1991, in order to increase security and reliability of the trains. The essential error was the unreliability of traction devices. Installation of additional two supplementary diesel-motors of 150 kW was claimed to power auxiliary devices and train heating. Also, the replacement of electric traction motors and the entrance doors was required.

The original Yugoslav numeration of a unit looked like this: 610-001 + 617-001 + 617-002 + 617-003 + 610-002, the 610 series representing the motor wagons, and 617 the remaining trailers. After the renumbering for Croatian Railways, the units were numbered as follows: 7021-001 + 4021-001 + 5021-001 + 4021-002 + 7021-002. The motor wagons belong to 7021 series, the wagon with bar is marked as 5021, and the remaining two trailers are numbered as 4021 series. The international fore-number for all the compounds of the train is 98 78. Nowadays there is a single unit left in traffic, namely: 7021-009 + 4021-002 + 5021-009 + 4021-008 + 7021-004.