Editing GWR 4100 Class (section)

==Badminton class==

The first member of the class, No. 3292, was completed in December 1897 with a [[Steam dome|domed]] parallel [[boiler]], a raised [[Belpaire firebox]] and an extended, built-up [[smokebox]] similar to that used on the Duke Class.<ref name=Hol74>{{harvnb |Holcroft |1971 |p=74}}</ref> The outside frames were curved over each driving wheel axle.<ref name=OSNa32>{{harvnb |Nock |1977 |p=32}}</ref> It was named ''Badminton'' in April 1898.<ref name=OSNa33>{{harvnb |Nock |1977 |p=33}}</ref> A batch of eleven locomotives, Nos. 3293 to 3303, were completed between April and July 1898, with a further batch of eight, Nos. 3304 to 3311, between September 1898 and January 1899.<ref name=OSNa34>{{harvnb |Nock |1977 |p=34}}</ref> The class were the first locomotives on the GWR to be fitted with copper Belpaire fireboxes.<ref name=Hol68>{{harvnb |Holcroft |1971 |p=68}}</ref> The penultimate example, No. 3310 ''Waterford'', was fitted with a domeless parallel boiler, a steel Belpaire firebox, and an enlarged cab.<ref name=OSNa34/><ref name=Hol68/>

The class were fitted with a steam chest and [[slide valve]]s located beneath the [[Cylinder (locomotive)|cylinders]]. The valves were driven by [[Stephenson valve gear]].<ref name=Hol67>{{harvnb |Holcroft |1971 |p=67}}</ref> This inverted arrangement of slide valves and steam chest, originally introduced by [[William Stroudley]] of the [[London, Brighton and South Coast Railway|LB&SCR]], allowed the valves to drop away from the cylinder's steam port faces when the regulator was closed, thus reducing wear.<ref name=Hol62>{{harvnb |Holcroft |1971 |p=62}}</ref> Because the steam chest was below the cylinders, and not between them, the latter could have an increased diameter. The centre line of the cylinders was inclined at an angle of 6° to the centre line of the valves, each centre line being aligned with the driving centre. This arrangement allowed the valve rods to be driven directly from the expansion link.<ref name=Hol62/><ref name=OSNa10>{{harvnb |Nock |1977 |p=10}}</ref><ref name=OSNa46>{{harvnb |Nock |1977 |p=46}}</ref> First used on the Armstrong and [[GWR 3031 Class|3031]] Classes, this arrangement of cylinders, valves and valve gear was subsequently used on all GWR outside framed 4-4-0s, with the slide valves being eventually replaced by [[Piston valve (steam engine)|piston valves]].<ref name=OSNa27>{{harvnb |Nock |1977 |p=27}}</ref>

The [[crankpin]]s for the [[coupling rod]]s were placed in line with the corresponding inside crankpins for the [[connecting rod]]s.<ref name=OSNa34/><ref name=Hol68/> This arrangement was also developed by Stroudley, who claimed that the motion of the inside cranks was smoothly transferred to the coupling rods, as happens in an outside-cylindered engine, where the connecting rod acts directly on a crankpin shared with the coupling rod. According to Stroudley, the axleboxes, bearing surfaces, [[Steam locomotive#Chassis|hornblocks]] and coupling rods of locomotives with outside cylinders had a service life twice as long as those on inside-cylindered examples.<ref name=OSNa13>{{harvnb |Nock |1977 |p=13}}</ref> However, by aligning the two cranks together, heavy balancing weights were required on the driving wheels, at 180° to the outside crank, to counteract the combined mass of the cranks and rods.<ref name=OSNa34/> The Badmintons had massive crescent-shaped balancing weights, which made the unmounted pairs of wheels difficult to handle in the workshop.<ref name=Hol68/>

{| class="wikitable"
!colspan=2 align=center|Numbers
!colspan=2|Names
|-
!width="90" align=center|First
!width="90" align=center|Second (1912)
!width="110" align=center|First
!width="110" align=center|Second
|-
|align=center|3292
|align=center|4100
|[[Badminton House|Badminton]]
|-
|align=center|3293
|align=center|4101
|[[William Barrington, 6th Viscount Barrington|Barrington]]
|-
|align=center|3294
|align=center|4102
|[[Blenheim Palace|Blenheim]]
|-
|align=center|3295
|align=center|4103
|[[Frederick Ponsonby, 6th Earl of Bessborough|Bessborough]]
|-
|align=center|3296
|align=center|4104
|[[Cambria]]
|-
|align=center|3297
|align=center|4105
|[[Earl Cawdor]]
|-
|align=center|3298
|align=center|4106
|[[Grosvenor (surname)|Grosvenor]]
|-
|align=center|3299
|align=center|4107
|[[Hubbard (locomotive)|Hubbard]]
|[[Alexander Hubbard]]
|-
|align=center|3300
|align=center|4108
|[[Henry Percy (Hotspur)|Hotspur]]
|-
|align=center|3301
|align=center|4109
|[[Monarch]]
|-
|align=center|3302
|align=center|4110
|[[Mortimer]]
|[[Charles Mortimer]]
|-
|align=center|3303
|align=center|4111
|[[Marlborough, Wiltshire|Marlborough]]
|-
|align=center|3304
|align=center|4112
|[[Oxford]]
|''Name removed in 1927''
|-
|align=center|3305
|align=center|4113
|[[Samson]]
|-
|align=center|3306
|align=center|4114
|[[Shelburne (locomotive)|Shelburne]]
|-
|align=center|3307
|align=center|4115
|[[Shrewsbury]]
|''Name removed in 1927''
|-
|align=center|3308
|align=center|4116
|[[Savernake, Wiltshire|Savernake]]
|-
|align=center|3309
|align=center|4117
|[[Shakespeare]]
|-
|align=center|3310
|align=center|4118
|[[Waterford]]
|-
|align=center|3311
|align=center|4119
|[[Wynnstay]]
|-
|}

One locomotive of the Badminton Class was rebuilt with an experimental boiler. With the impending opening of the direct [[Reading–Taunton line]] which was of more undulating nature than the route via Bristol, there was a need to ensure that the most appropriate locomotives were provided. [[George Jackson Churchward|Churchward's]] Chief Assistant, F.G. Wright, designed a large boiler with a very deep firebox, which was fitted to No. 3297 ''Earl Cawdor'' in July 1903.<ref name=OSNa62-63>{{harvnb |Nock |1977 |pp=62–63}}</ref> The boiler was designed to hold a large volume of hot water, forming a reservoir to assist the locomotive running along an undulating line.<ref name=OSNa62>{{harvnb |Nock |1977 |p=62}}</ref> It also provided a steam space of {{convert|85.13|cuft|m3|abbr=on}} compared to the {{convert|76.2|cuft|m3|abbr=on}} of the Standard No. 4 boiler, the larger of the two standard boiler models fitted to the 4-4-0s.<ref name=Hol82>{{harvnb |Holcroft |1971 |p=82}}</ref><ref name=OSNa63>{{harvnb |Nock |1977 |p=63}}</ref> This increase in volume was intended to provide a reservoir of steam.<ref name="OSNa63"/> The firebox was set deep between the coupled axles, with a horizontal grate.<ref name=OSNa62/> The intent was to allow a thick fire to be built up, increasing the area of the firebox in contact with the fire, and decreasing the temperature gradient along the firebox plates, thus reducing the risk of broken firebox stays.<ref name=OSNa62-63/> The boiler was pressed to {{convert|210|lbf/in2|MPa|abbr=on}}.<ref name=OSNa63/> No. 3297 was also fitted with a large cab with two side windows, reminiscent of [[North Eastern Railway (United Kingdom)|North Eastern]] practice.<ref name=OSNa63/><ref name=RCTSGWR7>{{harvnb |le Fleming |1954 |p=G30}}</ref> The locomotive was regularly rostered on the most demanding trains, but it soon became apparent that it was not up to the work demanded and it was relegated to secondary duties. In October 1906 the boiler was removed and replaced by a Standard No. 4 boiler, the North Eastern style side-window cab having been replaced by a Churchward type in November 1904.<ref name=RCTSGWR7/>