Well, put simply, a “4F” is an 0-6-0 goods steam locomotive which has its origins in the range of smaller 0-6-0 designs initiated by the Midland Railway company in the late 19th Century.

“4F” is the power classification assigned to the loco.  “4” indicates a loco of medium power (in the range 0 – 9), and “F” stands for “Freight”.  (Even though the railways commonly refer to “freight” as “goods”)

http://en.wikipedia.org/wiki/LMS_Fowler_Class_4F

If you want to know more about 4Fs, why not take a look at these excellent and informative books.

A defence of the Midland/LMS Class 4 0-6-0 by Adrian Tester

LMS Locomotive Profile 10 – Std Class 4 Goods – By Wild Swan

LMS Profile 10 Pictorial Supplement 0-6-0 – By Wild Swan

Fowler Locomotives – A pictorial history by Brian Haresnape

 

 

 

 

 

 

 

 

LMS Locomotive Design and Construction – A.F. Cook

 

 

 

 

 

 

 

 

 

Raising Steam on the LMS.  The evolution of LMS Locomotive Boilers – A.F. Cook