231 PO 3701 - 3721 | TrainsDepot.org

231 PO 3701 - 3721

Also known as:

4-231 F 701 - 721

Vehicle type:

Steam locomotive

Registration country:

France

Railway companies:

PO-Midi - Chemins de fer de Paris à Orléans et du MidiSNCF - Société Nationale des Chemins de Fer français

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In service:

from 1932

Gauge:

Standard gauge (1'435 mm)

Wheel arrangement:

2′C1′

Length without tender (mm):

13'700 mm

Length with tender (mm):

23'633 mm

Height (mm | over lowered pantograph):

4'250 mm

Service weight (t):

101,8 t

Power output (x'xxx kW / x'xxx hp):

2'207 kW
3'000 hp

Driving wheel diameter (x'xxx,xx | mm | new / worn):

1'950 mm

Leading wheel diameter (x'xxx,xx | mm | new / worn):

960 mm

Trailing wheel diameter (x'xxx,xx | mm | new / worn):

1'150 mm

Maximum speed (km/h):

130 km/h

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Vehicle's history

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1929

André Chapelon was a renowned railway engineer and a leading specialist in compound expansion. He progressively focused on increasing steam locomotive performance through major improvements to steam circuits, valve gear, and rigorous thermodynamic calculations.

At the end of the 1920s, the Pacific locomotives of the Paris-Orléans Railway (PO) faced an increase of the trains weight. More powerfull locomotives were needed to ensure the heavy load. However the PO was in a difficult economic situation, and in 1929, the company decided that no more steam locomotives would be produced, and instead decided to electrify its main line from Paris to Toulouse. But powerfull steam locomotives were needed and the only option of the moment was to rebuild the pre-existing locomotives.

In 1929, André Chapelon, engineer of the PO railway proposed to proceeded to the rebuilt of a member of the 231 PO 3501 - 3590 series following his principles. The chief mechanical engineer, Mr Epinay, greenlit the project and in 1929, no. Pacific 231 PO 3566 was rebuilt in the Railway workshops at Tours. The end result was an increase of the locomotive power of approximatly 50% from 1'950 HP (1'923 imp. HP) to 3'000 HP (2'960 imp. HP).

This rebuilt locomotive became the prototype of this series, renumbered 231 PO 3701, and marked the beginning of the so-called “Chapelon first-type” transformations.

Following this success, 20 additional locomotives from the 231 PO 3501 - 3590 series were rebuilt in 1932 to the same principles and renumbered 231 PO 3702 - 3721.

Sources: https://www.loco-info.com/view.aspx?id=-694&t=Country&cookies=accept, https://fr.wikipedia.org/wiki/231_PO_3701_à_3721, https://fr.wikipedia.org/wiki/231_PO_3501_à_3589, https://fr.wikipedia.org/wiki/231_Nord_3.1111_à_3.1130_et_3.1171_à_3.1198

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