Mexican Railway 2-8-0 "Consolidation" Type Locomotives

Class 71 (Locobase 6740)

Data from MexRy 1939 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive collection.

This relatively powerful set of Consolidations -- RI works #3087-3089 -- actually preceded the Alcos and Baldwins that were supplied over the next decade. They must have originally used Stephenson link valve gear and been retrofitted with Baker radial gear later. 72 differed from its two sisters at the time of the 1939 book in having 21"-diameter cylinders.

Class 81 (Locobase 6741)

Data from MexRy 1939 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive collection.

Locomotives from this Glasgow builder often found their way onto the Mexican's rails. Unlike the American-built Consolidations, this class had Belpaire fireboxes. Locobase suspects there were at least 4 in the class (works #4736-4739) with two having been withdrawn before the compiling of the 1939 diagram book.

Class G-1 (Locobase 6738)

Data from MexRy 1939 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive collection.

Locobase had doubts that adding 2 feet to each boiler tube, compared with the earlier 64, would have had no impact on wheelbase, weight on the drivers, total weight, etc. Still, there's no contrary evidence.

Class G-2 (Locobase 6737)

Data from MexRy 1939 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive collection.

The date for this locomotive's arrival on the MR puts it very close to the first years of Consolidations. That it was still part of a diagram book 64 years later suggests that the Railway was both strapped for cash and unwilling to throw away anything that still worked.

Class G-3 / GR-23 & GR-24 (Locobase 6742)

Data from MexRy 1939 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive collection.

The most numerous class of Consolidations on the Mexican Railway, this design was procured over an 8-year period. Baldwin's works numbers were 16473-474, 24209, 24218, 24720-24721, 24724, 24734, 30502, 30590, 31634, 31638, 32345, 32480, 32481, 32563. For some reason, 91's firebox was 2" shorter, which reduced direct heating surface to 198.7 sq ft.

By 1939, 5 (93, 96, 100, 104, 105) had been refitted with Baker radial valve gear.

Class GR-27 (Locobase 3236)

The first 11 of these came in 1921 to work the Vera Cruz-Mexico City mainline freights, which Railway Age (12 Nov 1921) noted covered 264 miles and "abounds in curves and grades." RA singled out a tunnel with a curve of 17 /12 deg radius. Maximum grade for this line was 4 1/2% (ca. 225 ft in the mile). RA also noted how quickly this order, taken on 25 May 1921, was filled: the last of 11 engines was shipped on 1 July.

Locobase note: The specs are identical to those for a pair of Consolidations bought by the Maryland & Pennsylvania in 1914 (see Locobase 6025). Seems to be a clear case of an order filled from a stock design, although RA says nothing about it.

Specifications
Class	71	81	G-1	G-2	G-3 / GR-23 & GR-24	GR-27
Locobase ID	6740	6741	6738	6737	6742	3236
Railroad	Mexican Railway	Mexican Railway	Mexican Railway	Mexican Railway	Mexican Railway	Mexican Railway
Whyte	2-8-0	2-8-0	2-8-0	2-8-0	2-8-0	2-8-0
Road Numbers	71-73	81, 84	69	64	90-105	200-210
Gauge	Std	Std	Std	Std	Std	Std
Builder	Rhode Island	Neilson & Co	Burnham, Parry, Williams & Co	Burnham, Parry, Williams & Co	Burnham, Williams & Co	Baldwin
Year	1895	1894	1882	1875	1899	1921
Valve Gear	Baker	Stephenson	Stephenson	Stephenson	Stephenson	Walschaert
	Locomotive Length and Weight
Driver Wheelbase	15'	15.50'	14.79'	14.71'	14.25'	14.25'
Engine Wheelbase	23'	22.67'	22.62'	22.62'	22.33'	23.33'
Ratio of driving wheelbase to overall engine wheebase	0.65	0.68	0.65	0.65	0.64	0.61
Overall Wheelbase (engine & tender)	53.25'	50.92'	46.67'	46.50'	52.92'	56'
Axle Loading (Maximum Weight per Axle)
Weight on Drivers	143812 lbs	122963 lbs	99869 lbs	99869 lbs	129830 lbs	169000 lbs
Engine Weight	156645 lbs	132277 lbs	107630 lbs	107630 lbs	142814 lbs	191700 lbs
Tender Light Weight	120000 lbs	108170 lbs	73900 lbs	73900 lbs	120000 lbs	245000 lbs
Total Engine and Tender Weight	276645 lbs	240447 lbs	181530 lbs	181530 lbs	262814 lbs	436700 lbs
Tender Water Capacity	6000 gals	3500 gals	4000 gals	4000 gals	6000 gals	6000 gals
Tender Fuel Capacity (oil/coal)	2500 gals	2058 gals	2327 gals	2327 gals	2500 gals	2500 gals
Minimum weight per yard of rail on which locomotive could run	59.92 lb rail	51.23 lb rail	41.61 lb rail	41.61 lb rail	54.10 lb rail	70.42 lb rail
	Geometry Relating to Tractive Effort
Driver Diameter	50"	48"	50"	50"	50"	51"
Boiler Pressure	175 psi	150 psi	150 psi	160 psi	175 psi	190 psi
Cylinders (dia x stroke)	20.5" x 26"	18.5" x 26"	20" x 24"	20" x 24"	20" x 26"	22" x 28"
Tractive Effort	32506 lbs	23637 lbs	24480 lbs	26112 lbs	30940 lbs	42915 lbs
Factor of Adhesion (Weight on Drivers/Tractive Effort)	4.42	5.20	4.08	3.82	4.20	3.94
	Heating Ability
Firebox Area	161 sq. ft	147 sq. ft	177 sq. ft	177 sq. ft	207.90 sq. ft	179 sq. ft
Grate Area	41 sq. ft	25.50 sq. ft	28.10 sq. ft	28.10 sq. ft	33.20 sq. ft	49.50 sq. ft
Evaporative Heating Surface	2167	1811	1551	1317	2047	2425
Superheating Surface						511
Combined Heating Surface	2167	1811	1551	1317	2047	2936
Evaporative Heating Surface/Cylinder Volume	218.17	223.89	177.73	150.92	216.53	196.85
	Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation	7175	3825	4215	4496	5810	9405
Same as above plus superheater percentage	7175	3825	4215	4496	5810	11041.91
Same as above but substitute firebox area for grate area	28175	22050	26550	28320	36382.50	39929.32
Power L1	4363.63	3777.00	3489.31	3364.41	4761.17	10381.58
Power MT	267.58	270.87	308.11	297.08	323.39	541.71