SEmG

Marsh I3 Class 4-4-2T

Marsh's early years at Brighton were not noted for much in the way of successful design. The best to come out of the works was undoubtedly the H1 class Atlantic, but that was basically an Ivatt locomotive. His next Atlantic designs, the I1 and I2 class tanks, both failed to impress, and in most cases failed to do the intended job as well as the locomotives they were supposed to replace, some of which eventually covered up to a million miles more than the Atlantic tanks!
 
75 The I3, one of the most important developments in British locomotive design during the twentieth century, as depicted by Nº75, in LBSC era livery.

photograph: Dave Searle collection

 
However, that was all set to change in 1908. The latest class of Atlantic tank, the I3, had first ventured out of the workshops in the form of Nº21 in September of 1907 and was, basically, a tank engine version of Billinton's successful B4 4-4-0 with 6' 9" wheels, 19" by 26" cylinders and a 180 lb sq ft saturated boiler. This was a great improvement on those that went before, but was still lacking that little bit "extra" that would make it a really useful engine. The next I3 to be built was Nº22 in March 1908 and for this Marsh was persuaded by his Chief Draughtsman to fit a superheated boiler with an extended smokebox on a saddle, 6' 7½" wheels and 21" by 26" cylinders. Although not the first superheated locomotive in Britain (both the L&YR and the GWR had experimented with superheating) it was the first superheated express engine and without doubt the one that showed superheating was the way forward. Trials with Nº22 showed it to be economical on both coal consumption and maintenance and a powerful performer on the heaviest of trains. Five more superheated I3s were built during 1908, then during 1909 and 1910 six more saturated versions were built so that a truly faircomparison could be made between the saturated and superheated boilers. When compared with saturated I3s, H1s and B4s the superheated I3s consumed 30lb of coal per mile as against the 36, 40 and 42lb of the others. Furthermore, they were capable of operating the heaviest of LB&SCR expresses over all routes without problem and could work the 84 miles from Clapham Junction to Fratton in 1 hr 40 mins non-stop, despite having just 2,110 gallons water capacity. In one trial Nº23 worked the "Sunny South Special" through from Willesden Junction to Rugby much to the astonishment of the L&NWR that usually provided two engines for this duty, a fairly lightly loaded 250 tons!

The main thing to make the other railways sit up and take notice was the fuel economy, though they were not lacking in awareness of the other benefits. A superheated I3 could leave Brighton with a piled high bunker containing some 3¼ tons of coal and take the above-mentioned train to Rugby and back without need for water en route or recoaling at Rugby, a performance of about 27lb per mile, assuming no coal remaining when returned to Brighton. The remainder of the class was built with superheated boilers (the saturated ones were rebuilt as superheated by Maunsell) and the I3s ruled supreme until electrification pushed them to the secondary routes of the Crowborough, East Grinstead and Tunbridge Wells lines.

 
Nº78, photographed in the more ornate lined LB&SCR livery.

photograph: Dave Searle collection

78
 
Numbers 21 to 81 were built under Marsh, the remainder under LB Billinton. This last 10 were slightly different in that they were provided with the vacuum brake and were fitted with different feed pumps, a higher cab roof and no superheater dampers. This dual brake facility made the Billinton engines very useful for working ambulance trains during the First World War,
 
The hero of the day was BK Field, Chief Draughtsman, whose persistence was rewarded when he finally persuaded Marsh to try superheating, though few today will have heard of him, and even fewer recognise his contribution to the development of the British steam locomotive.
 
2075 Nº 2075 photographed during Southern Railway days, location not known.

photograph: Mike Morant collection

 
Nº 32086, a dual-braked Billinton version with the high cab roof, on shed in early British Railways days.

photograph: A J Wills photographic collection

32086
 
32077 Nº32077 captured on shed at Redhill on 24th February 1951.

photograph by Les Darbyshire

 
The class had a very successful career and when electrification of the Brighton lines started to displace them they found new jobs elewhere. Initially cut down slightly by reducing the height of the boiler mountings and rounding-off of the cab roofs to work on the Eastern section, they subsequently moved further afield with, from 1938, four being allocated to Salisbury shed to work trains from there to Portsmouth and, in 1941, two going to the GWR at Worcester where they easily handled the traffic normally worked by that company's Prairie tanks. By 1943, however, all of the class had returned to the Central section.
 
Unfortunately none of these mould-breaking locomotives survived the cutter's torch with the last, Nº32091, being withdrawn in April 1952 and cut up at Ashford the following January, still making a name for the class as Nº32091 was the first ex-LB&SCR express passenger locomotive to be cut up there.
 
The worksplate from Nº86.

photograph: Dave Searle collection

32086
 

Technical Details

Introduced:
Driving Wheel:
Cylinders (2):
Boiler Pressure:
Coal Capacity:
Water Capacity:
Tractive Effort:

 

1907
6 ft 7½ ins (Nº21 6 ft 9 in)
21 in x 26 in (Nº21 19 in x 26 in)
180 lb sq in
3 tons
2,110 galls
22,065 lbs
 
LBSC Nº SR Nº # BR Nº Built Superheated Withdrawn
21 §
22
23
24
25
26
27 §
28 §
29 §
30 §
75 §
76 §
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2075
2076
2077
2078
2079
2080
2081
2082
2083
2084
2085
2086
2087
2088
2089
2090
2091
32021
32022
32023
-
32025
32026
32027
32028
32029
32030
32075
32076
32077
32078
32079
32080
32081
32082
32083
32084
32085
32086
32087
32088
32089
32090
32091
Oct 1907
Mar 1908
Feb 1909
Mar 1909
Mar 1909
Mar 1909
May 1909
Dec 1909
Dec 1909
Mar 1910
Mar 1910
Mar 1910
Oct 1910
Nov 1910
Nov 1910
Dec 1910
Dec 1910
Aug 1912
Aug 1912
Aug 1912
Aug 1912
Sep 1912
Nov 1912
Nov 1912
Dec 1912
Mar 1913
Mar 1913
Sep 1919
When new
When new
When new
When new
When new
Feb 1925
Oct 1923
May 1927
Jan 1926
Nov 1925
Jan 1927
When new
When new
When new
When new
When new
When new
When new
When new
When new
When new
When new
When new
When new
When new
When new
Sep 1951
May 1951
Jul 1951
Nov 1944
Jan 1950
Aug 1951
Feb 1951
Sep 1951
Feb 1951
Aug 1951
Oct 1951
Dec 1950
Mar 1951
Jan 1951
Nov 1951
Mar 1950
Aug 1951
Jun 1951
Jun 1951
Mar 1951
Jul 1950
Oct 1951
Oct 1950
Oct 1950
Apr 1951
Nov 1950
Apr 1952
§ Fitted with saturated boilers when built
# Between 1923 and 1928 SR numbers were the LBSC numbers with the added prefix 'B'

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This page was last updated 27 April 2011

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