The SNCF Class BB 900 was a class of 35 mixed-traffic electric locomotives built between 1936 and 1937 for État. The class was a development of the pre-war Midi Class E4700 and very similar to the later Class BB 300 and Class BB 325. Initial use was on the Paris–Le Mans line.[1] The class was withdrawn in 1987 after 50 years in service.[2]
History
Context
In the early 1930s, the economic crisis hit and the government undertook major works to support employment, known as the Marquet plan. It was in this context that the decision was made to electrify the line from Paris-Montparnasse to Brest, between Paris and Le Mans. In anticipation of the completion of this work, the State company ordered two series of electric locomotives: the Class 2D2 5400 for the passenger services and the BB 900 for freight trains.
The BB 900 were a development of the Midi E 4200 and E 4700 classes. The Midi company had a long experience in electric traction and the BB Midi were very successful. Compared to their predecessors, the new locomotives had different gear ratios, the profile of the line being less hilly than that of the lines of the South. Likewise, they were not fitted with rheostatic braking, being less useful on the plain.[3]
Service
The class was ordered by État from Alsthom in 1934. The class was originally numbered BB 101–BB 135. Upon delivery, from 1936 to 1937, the class was assigned to the Montrouge depot. Their main duties were operating heavy freight services on the newly electrified Paris-Le Mans line. Some passenger trains are also operated by these locomotives, at the head of Talbot trainsets. A BB 900 at the head of a 100t (98 long tons; 110 short tons) train could match the running of a Somua Z 3800 railcar. During the tests a speed of 107km/h (66mph) would have been sustained.
One locomotive was a casualty of the Second World War. BB 125 was destroyed in July 1944 in the air attack on the Maintenon viaduct by the USAAF.[4]
In the SNCF renumbering scheme of 1950, the class was renumbering BB 901–BB 935, omitting BB 925.
During the 1960s the class underwent major overhauls. Shortly after, some members of the class were transferred to the depot in Limoges, with the remainder following around 1975.
The modernisation of the SNCF electric fleet entailed the gradual withdrawal of the class from 1982 to 1987.[3]
Technology
The technology used was the same as that proven on the Midi machines, with an increase in power compared to the BB 4700. As with their predecessors, the bogies are linked together and include shock devices.
The body was made of welded steel, integrated with the frame. It had two driving cabins. The traction motors were nose suspended: on one side, the motor rests on the central cross member of the bogie supported by helical springs, on the other side it rests on the axle to be driven. The engine/bogie transmission is bilateral, as with all the other BB Midi, with a ratio of 3.273.
Regarding the electrical part, the 4 motors are of the M1E type and had a one-hour rating of 370kW (500hp) at 1500 V. They could be connected in series, series-parallel (2 by 2), parallel. Unlike the Midi BB 4700, these locomotives did not have rheostatic electric braking which was deemed unnecessary on the Paris - Le Mans line.
The motors were controlled by means of a 29-notch controller, wired as follows:
0: open circuit
1 to 10: series operation, on starting resistors
11: direct series operation
12 to 18: series-parallel, on resistors
19: direct series-parallel
20 to 27: parallel, on resistors
28: full field parallel
In addition to this controller, the driver also had a shunt lever[a] with 6 positions allowing "reduced field" operation and a direction switch.
The current collection was by two Faiveley pantographs. The high voltage circuit consisted of a double disconnect switch and a circuit breaker. The motors were coupled via a battery of electro-pneumatic contactors.
During the general overhaul, the end doors were removed and the engine control and electrical wiring completely refurbished.
Fleet list
État number
SNCF number
In service
Withdrawn
BB 101
BB 901
1 January 1936
27 April 1984
BB 102
BB 902
1 October 1936
26 June 1984
BB 103
BB 903
1 January 1937
22 January 1985
BB 104
BB 904
1 January 1936
January 1982
BB 105
BB 905
9 December 1937
December 1983
BB 106
BB 906
1 October 1936
December 1983
BB 107
BB 907
3 October 1936
January 1982
BB 108
BB 908
10 October 1936
28 February 1987
BB 109
BB 909
1 January 1936
28 February 1987
BB 110
BB 910
26 October 1936
January 1982
BB 111
BB 911
1 January 1936
7 January 1985
BB 112
BB 912
21 July 1937
12 September 1984
BB 113
BB 913
13 July 1937
January 1982
BB 114
BB 914
27 April 1936
31 May 1985
BB 115
BB 915
6 July 1937
5 March 1987
BB 116
BB 916
6 July 1937
30 August 1985
BB 117
BB 917
3 July 1937
January 1982
BB 118
BB 918
1 January 1937
December 1983
BB 119
BB 919
1 January 1937
January 1982
BB 120
BB 920
1 January 1937
16 April 1985
BB 121
BB 921
1 January 1937
December 1983
BB 122
BB 922
1 January 1937
December 1983
BB 123
BB 923
1 January 1937
30 May 1984
BB 124
BB 924
1 January 1937
3 April 1987
BB 125
1 January 1937
25 July 1944
BB 126
BB 926
1 January 1937
28 February 1987
BB 127
BB 927
1 June 1937
19 March 1984
BB 128
BB 928
10 August 1937
28 February 1987
BB 129
BB 929
1 January 1937
28 February 1987
BB 130
BB 930
5 August 1937
19 March 1984
BB 131
BB 931
1 January 1937
January 1982
BB 132
BB 932
1 January 1937
14 June 1985
BB 133
BB 933
4 August 1937
December 1983
BB 134
BB 934
29 July 1937
December 1983
BB 135
BB 935
13 October 1937
January 1982
References
↑Garvin, Brian; Fox, Peter; Appleby, Chris (1986). SNCF/French National Railways. Sheffield: Platform Five. p.9. ISBN0-906579-62-7.
