Talk:LB&SCR I3 class

Driving wheels

Although the prototype I3 locomotive (BR №32021) had 6'9" driving wheels, the remainder of the class was constructed with 6’7½” drivers. ˜˜˜˜ —Preceding unsigned comment added by Crudshoveller (talk • contribs) 14:49, 26 October 2009 (UTC)

Other classes

There were also classes I1, I2, and I4, which last was superheated. All are said - i.a. by OJ Morris (1952) - to have been failures. What else, besides superheating, was so special about the I3?Delahays (talk) 12:47, 19 November 2013 (UTC)

The I3 class had larger driving wheels - 6'9" diameter, as used in the B4 class instead of 5'6" - which made them much more suitable for high speed running. They also had significantly larger boilers:

Class	I1	I2	I3	I4
Diameter	4'3"	4'6"	4'10"	4'6"
Barrel length	10'10.75"	10'10.75"	11'5"	10'10.75"
Firebox length	5'8.25"	5'8.25"	7'7"	5'8.25"
Heating surface	947.5 sq. ft.	1097	1269 (+ 305 sup.)	893 (+ 215 sup.)
Grate area	17.43 sq ft	17.35	24	17.35
Pressure	170 lb/sq in	170	160	160

The cylinder arrangement was different, in particular piston valves were used on the I3 and I4 classes instead of slide valves. But mostly it would have been the 33% increase in grate area and the extra heating surface. --Redrose64 (talk) 17:22, 19 November 2013 (UTC)