Compiling an "all-time" roster for most railroads, especially large railroads that began in the 19th century, is very difficult.
For many railroads, such as the New York Central, its nearly impossible to accurately list EVERY locomotive ever owned by the company.
But the NYSW is probably just small enough that an accurate all-time roster shouldnt be too difficult to determine. hopefully!

The steam era of the NYSW is complicated and confusing, mainly due to the Erie railroad control between the years 1898 and 1940.
But if we divide up the NYSW steam era into it's three clear divisions, it might be managable..

Steam era #1 - Beginning of the NYSW to Erie control - 1881 to 1898.
Steam era #2 - The Erie Years - 1898 - 1940.
Steam era #3 - Independance to "end of steam" - 1940 - 1947.

The following steam roster data is compiled from four different books:
The New York Susquehanna & Western Railroad. - by  Robert E. Mohowski
Erie Power - by Al Stauffer
Susquehanna  - by John Krause and Ed Crist.
The History of the New York Susquehanna &  Western Railroad -  by Walter Arndt Lucas, published by
                                                                                                                            the Railroadians of America in 1939
                                                                                                                            and reprinted and updated in 1980.

there are some roster discrepncies between the books!
when books disagree, I am going with the newest book (Mohowski) 
assuming the latest data is the correct data, but this may or may not be a correct assumption! ;)

There are also two other NYSW books which I do not yet have in my collection:
Susquehanna – from Shortlines to Stackpacks - by Ken Karlewicz and Scott Hartley
New York Susquehanna & Western, In Color. - Morning Sun Books.

And as always, I recieve lots of help on these lists from the great railfans and historians
at www.railroad.net, www.railfan.net and www.rypn.org. (see links below)
thanks!
 

 
 
 

Susquehanna Steam Locomotives:
 


Steam Era #1 - 1881-1898
"Prior to Erie Control, Susquehanna operated with 87 Locomotives" - Mohowski
nearly all of these 87 locomotives were of the 4-4-0 and 2-6-0 type.
Even though the Susquehanna was not fully an Erie subsiderary until 1898, NYSW locomotives were ordered in "sub sets" of Erie locomotive orders before then,
With the same specifications as the Erie engines, but lettered "Susquehanna" on the tender, and given an independent NYSW 2-digit number series.
4-4-0 Type - class? Number in class?
Wheel arr road number class builder/date retired/scrapped notes photo
4-4-0 12 ?        
             
             
2-6-0 Type
Class F25 - 22 locomotives, all 22 in the class built for NYSW - Rogers 1881-1889, numbers 18-42, but not inclusive, there were gaps in the number series.
Class F26 - 7 locos built for Erie, Numbers 45-51,Rogers, 1892 & 1893, 4 of the 7 assigned to NYSW.(which four were NYSW is currently unknown)
Class F27 - 14 locos built for the Erie, Numbers 52-65, Rogers 1894-1897, 12 of 14 assigned to NYSW.(which 12 were NYSW is currently unknown) all locos in this class were Camelbacks
Class F28 - Rogers 1894-1895. Number of NYSW locos in this class currently unknown.
- all data from Stauffer
39 of the 87 pre-Erie NYSW locos can be confirmed as 4-6-0's..based on data so far.
Wheel arr road number class builder/date retired/scrapped notes photo
2-6-0 49 F27 Rogers 1894-1897   camelback  
2-6-0 57 F27 Rogers 1894-1897   camelback  
2-6-0 63          
2-6-0 65        
2-6-0 77          
             
Steam Era #2 -The Erie Years - 1898 - 1940
The Erie fully controlled the NYSW during these years, but the NYSW had its own locomotives lettered "Susquehanna"
and NYSW locos also had an independant number series from the Erie, NYSW locos generally had 2-digit road numbers, (except for the Russians) while Erie locos had 4-digit numbers. 
This is going to be the most difficult era to straighten out when it comes to what locos were actually assigned to the NYSW..it’s quite nebulous because of the Erie control.
For the purposes of this webpage, I am going to include any locomotive that was ever lettered "Susquehanna" on the tender, regardless of if it was leased or owned.

The following is the best I can do so far for a complete NYSW roster
for the years 1898-1940, it includes the 1905 Susquehanna Roster from the 1939 Walter Arndt Lucas book. Which shows a mix of original  NYSW locos, plus some new ones from the Erie.
Class names are Erie classes, not the original NYSW classes. In addition to the 1905 roster, other locos
that were known to be on the roster before 1940 are below. A total of xx locos are on this 
1898-1940 roster, however not all operated at the same time!

"The greatest number of locomotives owned at any one time by the NYS&W was 101. This number was reached in 1911 and continued until 1916, finally diminishing to the insignificant two owned in 1938."
-Lucas, 1939.

"In 1920, 92 locomotives were in use on The Susquehanna" - Mohowski
 
Wheel arr road number class builder/date retired/scrapped notes photo
4-6-0 25 G-odd Rogers, 1893   named "Phillip T. Nixon"  
4-6-0 26        
4-6-0 27          
4-6-0 29          
4-6-0 30        orig Erie 899, retired 1938
4-6-0 31          
4-6-0 32        
4-6-0 33          
4-6-0 34    Baldwin, 1891    orig Erie 289/975/1893, retired 1938
4-6-0 35        scrapped 1929  
4-6-0 36          
4-6-0 37      
4-6-0 38      
2-10-0 ???? J2     16 of the 75 Erie Russians assigned to NYSW before 1940 (see below)  
Steam Era #3 -Independence to "end of steam" - 1940-1947
The NYSW gained it's independence from the Erie in 1940.
Between 1940 and 1947, NYSW leased/owned a total of 31 Steam Locomotives in four wheel arrangements:
Five 0-6-0
Eight 4-6-0
Two 4-6-2 (but we have photos of FOUR!..perhaps renumburing? Or were there were actually four? Or..two were "Erie Years" pre-1940, and twp were Post-Erie)
Sixteen 2-10-0 (were they the SAME sixteen from pre-1940? Unknown..)
This era is more straight-forward and well documented, we should be able to figure it out with accuracy.
Wheel arr road number  class builder/date retired/scrapped notes photo
0-6-0 69  B-5      
0-6-0 75  B-5      
0-6-0 101  B-6  Erie Meadville-1912      
0-6-0 104  B-6  Erie Meadville-1912      
0-6-0 107  B-6  Erie Meadville-1912    
             
             
4-6-0 953  G-15b  Baldwin 1903/1904    Purchased from Erie - 12-1-1944  
4-6-0 960  G-15b  Baldwin 1903/1904  .  leased, never purchased  
4-6-0 961  G-15b  Baldwin 1903/1904    leased, never purchased
4-6-0 963  G-15a  Baldwin 1903/1904    Purchased from Erie - 12-1-1944  
4-6-0 966  G-15a  Baldwin 1903/1904    leased, never purchased  
4-6-0 969  G-15a  Baldwin 1903/1904    Purchased from Erie - 12-1-1944
4-6-0 970  G-15a  Baldwin 1903/1904    leased, never purchased  
4-6-0 972  G-15b  Baldwin 1903/1904    leased, never purchased
         
             
             
4-6-2 2451          
4-6-2 2514  K1      Purchased from Erie - 9-30-1943
4-6-2 2518          
4-6-2 2539  K1      Purchased from Erie - 9-30-1943
             
             
2-10-0 2433  J-2  1917    Purchased from Erie - 2-4-1943
2-10-0 2435  J-2  1917    Purchased from Erie - 12-1-1944