Technical data page 1
 

First series of PACIFICS - 20 units. P.O. 3701 - 3721 then P.O. Midi 231 - 701 to 231 -721 then S.N.C.F. 4 - 231 F 701 to 4 - 231 F 721.

• Boiler:

Belpaire type firebox, trapezoidal grate: 4.27sq. meter or 46 sq. ft.;
Internal boiler diameter (mean): 5.5 ft.
Length between tubes plates: 19.35 ft.
• Heating surfaces:
• Firebox: 15.45sq. meter;
• Nicholson's siphon: 2.465 sq. meter
• Smoke tubes: 180.62 sq. meter;
• Superheater: Robinson 32 elements, 72.85 sq. meter. on the 3566 (which became the 3701); Replaced by a 28 elements, 80 sq. meter HOULET superheater giving about 410° centigrades steam temp. on 3702-3721, because its use increased flowing sections in the smoketubes, allowing to increase the section of nozzles used in the KylChap, thus reducing back pressure proportionally.
• Pressure 17kg/cm²; or 243 P.S.I.
• KylChap exhaust, dual 1K/1C type;
• A.C.F.I. INTEGRAL feed water heater (heating feed water at above 100° centigrades, (oops 212° fahrenheit), fed by one injector or by its own steam powered pump. Details about those (used on most french engines, small to large, single or dual expansion because of the excellent efficiency and reliability of the system) feedwater heaters in the Typically French accessories page.
• One aux. injector supplying "cold" tender water.
• Hand-fired.

 
• Cylinders:
• High pressure (H.P.): Two external, 420 mm (16.53'') bore, 650 mm (25.6'') stroke, driving the second pair of wheels;
• Low pressure (L.P.): Two internal, 640 mm (25.1'') bore, 650 mm (25.6'') stroke, driving the first pair of wheels;
• High volume steam chests (1.8 times cylinder's capacity, a typical "Chapelon touch" preventing steam pressure drops during inlet phase);

 
• Valve gear: Two independent (i.e. 1 for H.P. group, 1 for L.P. group) classical Walschaerts mechanisms with separately-driven reversing screws, driving oscillating camshafts actuating dual seat valves, Lentz-Dabeg initial patent "à la sauce Chapelon". Separately adjustable valve gears are definitely a keypoint to good compound engines design. Awaiting a longer chapter already planned, a brief note about it. Valves diameters:
• Inlet and exhaust valves, H.P. and L.P.: 8.66'' (on 3566); L.P. inlet raised to 9.45'' on 3702-3721

 
• Steam circuit:
• Large flow section (240 sq. cm. or 37.2 sq. in.) balanced-valves regulator; All piping behind it incl. superheater set up to give at least the same flow section value (steam pipes section: 855 sq. cm. or 132.5 sq. in.).
• "Dead spaces" of cylinders and their inlet and exhaust tracts reduced to a strict minimum value without sacrifice to steam flow sections, can't find out of all those data the exact figure in % of cylinder capacity, but I'm sure it will unearth later by itself;
• Correctly shaped (with regard to steam flowing) steam pipes and cast tracts curves.

 
• Chassis: 32 mm. (1.35") thick steel frames assembled by cast iron horizontal and vertical spacers, and by L.P. cylinders unit.

 
• Wheels diameters:
• Truck: 0.96 m (3.14 ft.);
• Driving: 1.95 m (6.40 ft);
• Bissel: 1.15 m (3.77 ft.);

 
• Weights:
• Dry: 91.515 tons;
• Working order: 100.19 tons;

 
• Overall dimensions:
• Length: 13.7 meters or 44.91 ft. (engine only);
• Height: Top of chimney at 13.93 ft above track;

 
• Performances:
• Power available behind tender's coupling link: 2,500 H.P. (In France, 1 HP=736 watts...), or about 3,300 HP at cylinders at a speed of 90 km/h (56 mph); 2,400 H.P. at 68 mph (110 km/h).
• Consumption:
• Coal: 1.35 kg (less than 3 pounds) per HP per hour;
• Water:
• Tractive effort: To come...
• Test trains reports: Idem ...
• During tests of electric captation systems (!) in the fifties, pushing 1 electric locomotive and various measurement carriages for a total load of about 280 tons, machines of this type (NORD 231 E 19 and 231 E 35) reached 72 times (in fact each time the test was run...) 110.62 mph, highest recorded speed with a steam locomotive in France.

 
• Other details:

To load a full size version of this plan, click on the image. 196 Kbytes (.gif).

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An improved version of the first type. Specifications of these machines were used to build Chapelon's PACIFICS sold by P.O. railway to others french companies (Compagnie du NORD et Chemins de fer de l'EST). Only altered values (with regards to 3701-3721) are given:

• Boiler:
• Robinson superheater : 81.50 sq. meters or 876 sq. ft.

 
Cylinders:
• L.P. cylinders capacity increased; Stroke raised to 690 mm or 27.16'';
• L.P. cylinders inlet valves diameter: 10.43'' (265mm);
• L.P. cylinders exhaust valves diameter: 10.82'' (275mm);

 
• Weights:
• Working order: 100.88 tons

 
• Performances:

• Improvements in steam flow and superheating resulted in a power gain of about 200 H.P.. During tests using "braking locomotives", power output measured behind tender coupling link was:

 
• 2,800 H.P. at 56 mph.
• 2,650 H.P. at 68 mph.
• 2,550 H.P. at 75 mph.

 
• Tested on the dyno bench of Vitry sur Seine, a power of 3,000 H.P. was measured (i.e. on wheel tyres) at an equivalent speed of 62 mph (100 kmh) and sustained during two consecutive hours, water level being kept constant  in the boiler (i.e. with cold water introduced regularly in it as during normal operation; I believe that there is  NO "doped" values in Chapelon's experiments reports). At 75 equivalent mph., instant power was of 3,400 H.P., and 2,800 H.P. at 89.5 mph.

• Boiler:
• French shape said NORD firebox, so called because it was initially designed by engineers of La compagnie du NORD railroad company. These are long and narrow, using a rectangular grate which is fully inserted between chassis frames. Grid dimensions: 12.4 ft. long, 3.27 ft. wide or 40.5 sq. ft.. A Nicholson's siphon was fitted.
• Mean internal diameter: 1.80 m. or 5.9 ft.. The rearmost element is conical, with a diameter of 6.06 ft. at firebox side, and 5.66 ft. to the front.
• Length between tubes plates: 13.93 ft. or 4.25 meters.


Internally-finned of 60 x 65 milimeters (2.36'' x 2.56'') Serve's smoketubes were used (small tubes), Chapelon liked them much because of their 10% superior efficiency.
 

Click here for more details about Serve's tubes.

A Serve's smoketube. Often used  here until availability problems occured when the only factory manufacturing them closed. Where them used elsewhere in the world? Again, thanks to mail any info.
 

• Heating surfaces:
• Firebox: To come...
• Total (firebox + Nicholson's siphon+smoke tubes): 215.2 sq. meters or 2313 sq. ft..
• Houlet type superheater: 60.6 sq. meters or 651.5 sq. ft..

 
• A.C.F.I. INTEGRAL feedwater heater; more details here.
• Pressure: 286 P.S.I. or 20 kg/cm²;.
• Hand-fired.
• KylChap exhaust, dual 1K/1C type;

 
• Cylinders: Same as on first series of "PACIFICS", so:
• High pressure (H.P.): Two external, 420 mm (16.53'') bore, 650 mm (25.6'') stroke, driving the second pair of wheels;
• Low pressure (L.P.): Two internal, 640 mm (25.1'') bore, 650 mm (25.6'') stroke, driving the first pair of wheels;
• High volume steam chests (1.8 times cylinder's capacity, a typical "Chapelon touch" preventing steam pressure drops during inlet phase);

 
• Valve gear: As on PACIFICS. Two independent (i.e. 1 for H.P. group, 1 for L.P. group) classical Walschaerts mechanisms with separately-driven reversing screws, driving oscillating camshafts actuating dual seat valves, Lentz-Dabeg initial patent "à la sauce Chapelon" again. If you haven't read it yet, short note about separate valve gears.

 

 

Valves diameters:

• H.P. cylinders inlet valves diameter: 7.87'' (200mm.).
• H.P. cylinders exhaust valves diameter: 8.26'' (210mm.).
• L.P. cylinders inlet valves diameter: 10.43'' (265mm).
• L.P. cylinders exhaust valves diameter: 10.82'' (275mm).

 
• Steam circuit: Identical to P.O. 3701-3721

 
• Chassis: Again of typical "old continent fashion" type, 32 mm. (1.35") thick steel frames assembled and strengthened by cast iron horizontal and vertical spacers, and by the L.P. cylinders unit.

• Wheels diameters:

 
• Truck: 0.96 m (3.14 ft.).
• Driving: 6.06 ft (1.85 meter).

 
Weights:
• Working order: 107.28 tons.

 
• Overall dimensions:
• Length: 42.65 ft..
• Height: 13.9 ft.

 
• Performances:
• Power output: 4,200 HP
• Tractive effort: 57,268 lbs. ("Starting" mode, semi-single expansion mode specific to Du Bousquet - De Glehn architecture), 45,639 lbs. in normal compound mode.
• Consumption:
• Coal: 1.15 kg (2.53 pounds) per HP per hour;
• Water:
• 7.92 litres or 16.74 U.S. pints per HP per hour at 1,500 H.P.
• 7.4 litres or 15.64 U.S. pints per HP per hour at 3,000 H.P.

 
• Other details:

To load a 3464 X 1280 version of  this drawing, click on it. (.gif file, 183K)

Everything you've always wanted to know about Lentz- Dabeg valves!!

Click for a 1882 X 1408 version of  this drawing. (.gif file, 124K)
 

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