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LBSCR I4 Class 4-4-2T

photograph: Dave Searle collection

I4 class Nº31, in LBSC era livery. Note the distictive "louvre top" of the cab roof, for ventilation.

The huge success of Marsh's I3 class where the I1 and I2 classes had been so disappointing led to an attempt to recreate the trick with the I4 class, basically a superheated I2, in 1908.

Just five locomotives were built which were almost identical to the I2 class but with superheating, the cylinders' diameter increased from 17½ ins to 20 ins and the boiler pressure reduced to 160 lb. Sadly it was soon proved that the superheating alone was not the key to the success with the I3 tanks and the I4 engines were a big disappointment! In fact, in his book on the LB&SCR, Hamilton Ellis goes so far as to describe them as being 'shocking'!

The Southern Railway inherited these beasts and didn't know what best to do with them. There was a proposal to rebuild them along the lines of the I1x rebuilds of the I1 class, but in the end opted to scrap them. All bar one had gone by 1937, with the survivor, Nº34, hanging on until 1940. It is surprising that the creator of the H1 and H2 classes (albeit basically a copy of the Great Northern Atlantics) and of the I3 class made such a poor job of his other designs.

It is somewhat ironic to note that whilst Marsh was still building dismal 4-4-2Ts at Brighton, based on his experiences with the GNR, the GNR was busy introducing successful 0-6-2T locomotives that were, in turn, based very much on the 1902 E5 class of Marsh's predecessor, Billinton!

photograph: Dave Searle collection

Nº32, photographed in the more ornate lined LB&SCR livery.

Technical Details

Driving Wheel:
Trailing Wheel:
Cylinders (2):
Boiler Pressure:
Water Capacity:
Tractive Effort:
5 ft 6 ins
4 ft
67 tons (Approx)
17½ in x 26 in
160 lb sq in
2,238 galls
16,400 lbs


LBSC Nº SR Nº # Built Withdrawn
Sep 1908
Nov 1908
Nov 1908
Dec 1908
Feb 1909
Jan 1936
Jul 1937
Jul 1937
May 1940
Feb 1937
# Between 1923 and 1928 SR numbers were the LBSC numbers with the added prefix 'B'

This page was last updated 30 June 2004

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