LNWR Jubilee Class

Template:Use British English The London and North Western Railway (LNWR) Jubilee Class was a class of 4-4-0 4-cylinder compound locomotives by F.W. Webb. A total of forty were built from 1897–1900. Slightly unusually for the LNWR, the class received a number series, this being 1901–1940. All were named, mostly after Royal Navy battleships.

Iron Duke and Black Prince

File:Smoke box details of the Black Prince.jpg

Smoke box details of the Black Prince

The first two of this class were prototypes, built to different designs to permit a comparison. The first, No. 1501 the Iron Duke (later re-named Diamond Jubilee and then Jubilee), was a 4-cylinder simple locomotive with cylinders. The second, No. 1502 Black Prince, was not Webb's first compound, but was his first 4-cylinder compound and the first in the UK.Template:Sfnp The outside high-pressure cylinders were the same as Iron DukeTemplate:'s, the inside low-pressure cylinders were .

There was no simpling valve or other means for starting, and so when starting they just operated as small 2-cylinder simples.Template:Sfnp The Joy valve gear was shared between high and low pressure, with a rocking lever to the high-pressure valves. The inside cylinders were angled above the outside cylinders and although this could have been solved by cranking the rocking levers, this gave an uneven drive to the valves; valve-setting between both of them had to be a compromise position, ideal for neither, and so gave an uneven power distribution between high and low. Their running was thus not as free-running as it might have been, which Webb would address in his later designs.Template:Sfnp

These were also Webb's first designs with a leading bogie rather than a pony truck, which was also described as a "double radial truck".Template:SfnpTemplate:Sfnp The truck pivots geometrically at a point behind its rear axle, although there is no single mechanical pivot point. This motion is controlled instead, like Webb's earlier single radial truck, by curved radial slides, with a radius of curvature at the centre of the truck of Template:Cvt.Template:Sfnp

Another novel feature was that both locomotives were fitted with double chimneys. The smokebox was partitioned internally into upper and lower halves, the lower section exhausting through the front chimney and the upper tubes through the rear chimney. The blastpipes were fed separately, the front chimney from the left cylinders and the rear from the right. After some time in service, the two chimneys were replaced with a single chimney on an undivided smokebox and their performance and fuel consumption measured again. It was found that the compound locomotive had identical performance both with and without the double chimney, but that the simple locomotive was improved by it. The double chimney was re-fitted to Jubilee, but the production locomotives were built as compounds without it.

After around a year's running, the simple had run for 33,517 miles, with an average coal consumption of 40.3 pounds per mile and the compound (starting slightly later) for 23,503 miles with a consumption of 38.1 pounds per mile. The compound was thus cheaper by 2.2 pounds per mile, or 5%.

The ratio between LP and HP cylinders was 1.69, lower than that considered optimal.Template:Sfnp Webb's 3-cylinder compounds had used the more usual figure of 2. To improve this to 1.87, Webb had decided to increase the size of the LP cylinders to , and this was applied to the production locomotives.

Service

As with other Webb compounds, they were mechanically unreliable. As a result, George Whale rebuilt these as two-cylinder simple locomotives of the Renown Class, starting with 1918 Renown in 1908. Rebuilt engines retained their numbers. Rebuilding continued so that at the grouping of 1923, only 9 Jubilees remained, being 1903/4/8/11/12/15/23/27/29.

1908 Royal George was withdrawn in January 1923, but the remaining eight were allocated the LMS numbers 5110–5117, in sequence. Two, 1904 Rob Roy and 1923 Agamemnon were withdrawn 1923, without receiving new numbers. The LMS rebuilt the remaining six into Renowns in 1924, making the class extinct (Their subsequent history is discussed at LNWR Renown Class).

File:Every boy's book of railways and steamships (1911) (14758661642).jpg

Polyphemus with a London-Birmingham Down service, around 1910

A successor to this class, the Alfred the Great class, retained the 4-cylinder compound design but used two sets of valvegear, both Joy, allowing the LP cutoff to be controlled independently.Template:Sfnp

Locomotive list

LNWR Jubilee class locomotive list

LNWR No.	LNWR name	Crewe Works No.	Date built	Date rebuilt	LMS No.	Date withdrawn	Notes
1901	Jubilee	3856	Template:Dts	Template:Dts	5156		Named Iron Duke until December 1897, numbered 1501 until March 1899
1902		3857	Template:Dts	Template:Dts	5157		Numbered 1502 until March 1899
1903		3928	Template:Dts	Template:Dts	5110
1904	Rob Roy	3929	Template:Dts	—	(5111)	Template:Dts	Never carried its LMS number
1905	Black Diamond	3930	Template:Dts	Template:Dts	5137
1906	Robin Hood	3931	Template:Dts	Template:Dts	5149
1907	Black Watch	3932	Template:Dts	Template:Dts	5178
1908		3933	Template:Dts	—	—	Template:Dts
1909		3934	Template:Dts	Template:Dts	5159
1910	Cavalier	3935	Template:Dts	Template:Dts	5172
1911		3936	Template:Dts	Template:Dts	5112
1912		3937	Template:Dts	Template:Dts	5113
1913		3938	Template:Dts	Template:Dts	5132
1914		3939	Template:Dts	Template:Dts	5144		Renumbered 1257 in April 1920
1915		3940	Template:Dts	Template:Dts	5114
1916		3941	Template:Dts	Template:Dts	5155
1917		3942	Template:Dts	Template:Dts	5184
1918		3943	Template:Dts	Template:Dts	5131
1919		3944	Template:Dts	Template:Dts	5160
1920	Flying Fox	3945	Template:Dts	Template:Dts	5166
1921	John of Gaunt	3995	Template:Dts	Template:Dts	5134		Named T. H. Ismay until April 1913
1922		3996	Template:Dts	Template:Dts	5146
1923		3997	Template:Dts	—	(5115)		Never carried its LMS number
1924		3998	Template:Dts	Template:Dts	5183
1925		3999	Template:Dts	Template:Dts	5147
1926	La France	4000	Template:Dts	Template:Dts	5180		Shown at Exposition Universelle in Paris
1927		4001	Template:Dts	Template:Dts	5116
1928		4002	Template:Dts	Template:Dts	5173
1929		4003	Template:Dts	Template:Dts	5117
1930		4004	Template:Dts	Template:Dts	5142
1931		4045	Template:Dts	Template:Dts	5176
1932		4046	Template:Dts	Template:Dts	5162
1933		4047	Template:Dts	Template:Dts	5169
1934		4048	Template:Dts	Template:Dts	5165
1935		4049	Template:Dts	Template:Dts	5133
1936		4050	Template:Dts	Template:Dts	5150
1937		4051	Template:Dts	Template:Dts	5154
1938		4052	Template:Dts	Template:Dts	5161
1939		4053	Template:Dts	Template:Dts	5158
1940		4054	Template:Dts	Template:Dts	5170

References

• Template:Book-Ahrons-British Steam Railway Locomotive
• Template:Baxter-BritishLocoCat2B
• Template:Book-Van Riemsdijk-Compound Locomotives