SNCF Class BB 1600
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| SNCF Class BB 1600 | |||||||||||||||||||||
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 BB 1617 at Montereau in 1954 | |||||||||||||||||||||
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The BB 1600 were a series of fifty electric locomotives from the Chemins de fer du Midi, operating under direct current at a voltage of 1.5 kV.
They constituted the first generation of BB Midi, delivered between 1923 and 1926. Numbered E 4001 to 4050 in Midi, they became Class BB 4500 at the creation of SNCF, then were reclassified as shunting locomotives under the numbers BB 1601 – 1650 in the 1950s. The last members of the class were removed from SNCF inventories in 1984.
Elements of BB 1501 and BB 1632 have been used to reconstruct a locomotive exhibited under the original Midi registration E 4002 at the Cité du Train in Mulhouse, this locomotive having hauled the inaugural train for 1.5 kV direct current electric traction in France between Pau and Lourdes on 30 October 1922.
The Chemins de fer du Midi began electrifying its network in 1912 with alternating current at a voltage of 12 kV and a frequency of 16 ²⁄₃ Hz. To comply with the ministerial decision of 1920, it continued electrification, but with current DC at a voltage of 1.5 kV. To ensure train traction, it ordered two groups of locomotives: on the one hand the E 3100 and E 4800 for the fast passenger trains and on the other hand the BB for freight and other passenger services.[1]
The BB Midi were inspired by the locomotives put into service in 1915 on the British LNER and used the same electrical equipment manufactured by Dick Kerr.[2] A first tranche consisting of 50 locomotives, without prior prototypes, was delivered in 1923: E 4001 to 4020 and E 4501 to 4530, these would become the Class BB 1600s.[3]
Description
Main Features
The general architecture of the BB 1600 remained the same, with a few details and dimensional changes, for all other BB Midis.[3]
The locomotive consists of a profiled and riveted sheet metal body, fixed to the chassis which rests on the bogies. The body is made up of two driving cabs framing a compartment where the equipment is arranged on either side of a central corridor. Its roof supports the two pantographs. The cabins have four doors; two overlook the side faces, a third provides access to the equipment compartment and the fourth, rarely used in practice, is a front intercirculation door. The bogies, with two axles and one motor per axle, have wheels with a diameter of 1.40 metres (4 ft 7 in). The buffers and couplings are fixed on the crosspieces of the bogies, and not on the body and the bogies are coupled together: as a result, the chassis and the body only partially participate in the traction force and their structure can be made lighter.
BB 1600 specifics
The locomotives measure 10.850 m (35 ft 7.2 in) long and weigh 75 tonnes (74 long tons; 83 short tons). They are equipped with four Dick Kerr DK 80 motors giving them a continuous power of 735 kW (986 hp).[4] As they were intended for use on mountain lines with steep gradients, it was considered appropriate to equip them with regenerative braking which allows electricity to be returned to the catenary, particularly during descents, but this device is inoperative when the line voltage is too high.[5] The machines are equipped for operation in multiple units.[5]
In addition to these common characteristics, the two groups of locomotives differ only in their transmission, adapted to the use for which the machines were intended. E 4001 – 4020, originally intended for freight trains, had a gear train with a ratio of 5.066 and their speed was limited to 60 km/h (37 mph). However, they were quickly modified and brought to the standard of the later series. E 4501– 4530, reserved for haulage of passenger trains, had a gear train with a ratio of 3.136 which gave them a service speed of 90 km/h (56 mph).
