Which is a bigger engine the 4-10-2 or 2-10-4 ?

How do you define "bigger?" Are you talking about length? Weight? Tractive force? Horsepower? With or without tender? 

Regardless, "bigger" - whatever that is - isn't determined just by wheel arrangement. Individual engines would have to be compared.

Hello breezinup....

I would say weight, tractive effort, cylinder size, firebox grate areas so on...

the woman who loves the S.F.5011

Tiffany

http://en.wikipedia.org/wiki/4-10-2

In the USA, the type was used only on the Southern Pacific Railroad (SP) which called it the "Southern Pacific", and the Union Pacific Railroad (UP) which called it the "Overland" after their corporate sobriquet, "The Overland Route". Only sixty locomotives of this wheel arrangement were built for domestic service and all but one were constructed as simplex three-cylinder engines.

The 4-10-2's were essentially a 1920's Alco creation to promote their idea for 3-cylinder locomotives, which were never widely accepted on American railroads.

http://en.wikipedia.org/wiki/2-10-4

In contrast there were a greater variety of 2-10-4 locos built for several different railroads in North America, and they were all conventional 2-cylinder types. 2-10-4's continued to be developed and built through the 1940's, so they could be considered more modern than the 4-10-2's.

Some of the 2-10-4's were built lighter for lower axle loadings depending on the railway, so it's not so easy to make generalizations about the type.

I'll leave it to the experts to elaborate further.

The 2-10-4's were larger locomotives with the ATSF's being the physically largest and fastest and the C&O's the most powerful.

Here's a good link - http://www.steamlocomotive.com/texas/

ATSF #5000 is undergoing restoration for operation in Amarillo,Tx.-You may find this interesting.

http://www.railroadartifactpreservation.org/5000.html

I had an uncle who drove for ATSF, starting right after he mustered out of the service following WWII and through into the 1970s.  I recall him explaining that ATSF was more conservative on design because of the vast distances the trains traveled and the poor quality of the coal and water they often had to use.  Whatever the reasons, he explained that their locos tended to use lower pressures, have slightly less HP, bigger bearings but lowered RPM, etc.,  than those used in the east, but then they were run harder for longercontiuous  periods at high speeds because of the distances involved, and it worked out about the same.  This may expalin the "bigger by less power of their locos. 

BTW - He loved F3s, which he said were fantastic because while indidivual units had less power than other diesels, four could make what three bigger diesels did, and they could run repeatedly from Chicago to LA without mechanical mishap, over and over again.  I always loved the look of PAs, but he I recall he didn't like them at all.

To get a bit more "conceptual" here, as I see this sort of question appear on the Forum

from time to time:

The size of a railroad locomotive (running on the same gauge track) is not directly re-

lated to its wheel arrangement. There were bigger Hudsons and smaller Hudsons, for

example (C&O's were really big; Nickel Plate's were generally Pacific-sized). The original

Norfolk Southern had some compact Berkshires. There were some enormous (for their wheel arrangement) British 0-6-0's. The SP had the largest - and quite modern - Moguls (2-6-0), that had tractive effort ratings in the same category as some 2-8-2's and 4-6-2's.

Certainly the wheel arrangement is one of the important factors in a loco's overall size -

it has to be - but power, weight and even length are also dependent upon many other things.

Example: copies of steamers from the late 1930's built during WWII were often heavier

than the earlier "identical" locos because some lighter-weight alloys were being used in

the war effort, so the builders had to use thicker and/or heavier materials to achieve

the same integrity. (ATSF 4-8-4's were an example of this.) Looks can be deceiving.

Reviewing the multiple sources given above:

SP-2 class 4-10-2 steam locomotive built in 1926 by ALCO - Number in class 49

Driver diameter  63½ in

Weight on drivers   317,500 lb

Cylinder size (1 inside) 25 in dia × 28 in stroke (2 outside) 25 in dia × 32 in stroke

Boiler pressure 225 psi

Tractive effort 84,200 lbf,  96,540 lbf with booster

"Madam Queen" - AT&SF No. 5000 a single 2-10-4 locomotive in 1930 (36 more 2-10-4's were built in 1938 & 1944)

Drivers: 69" dia.  -  larger than most freight motive power at the time (74" on later models)

Weight on Drivers: 350,400 lbs

Cylinders: (2) 30" dia. x 34" stroke (same on later models)

Boiler Pressure: 300 psi (310 psi on later models)

Tractive Effort: 95,584 lbs (using c=0.7 in the TE equation) higher number in other sources?

Pennsylvania (PRR)  J1  2-10-4   1942 -

     Based on the Chessie's 40 T-1 class engines built in the 1930s  (125 similar PRR units built 1942-1944)

Driver Diameter 69"

Weight on Drivers 377800 lbs  -  Minimum weight of rail (calculated) on which locomotive could run: 126 lb/yard

Cylinders (dia x stroke) 29" x 34"

Boiler Pressure 270 psi

Tractive Effort 95106 lbs

The Pennsylvania RR had the largest single batch of 2-10-4's and they can be characterized as newer, heavier, more powerful than the 1920's  4-10-2's. In particular, the boiler pressure was higher.

Alco considered building 3-cylinder 4-10-4 or 4-12-4 locos for UP but the design evolved into the 4-6-6-4 Challengers (if I remember correctly). And the 4-12-2's fit into this story somewhere ...