GNR Class L1

The Great Northern Railway (GNR) Class L1 (LNER Class R1) was a 0-8-2T side tank steam locomotive designed by Henry Ivatt. It was originally designed for suburban passenger traffic on the Metropolitan City Lines.

A prototype was built in 1903, but it was overweight, so it was rebuilt with a smaller boiler and shorter side tanks. Ten more engines were then built to this modified design. During the "small boiler" era, the cylinders were lined to 18" to match the boilers.

In 1905 and 1906, thirty more engines were built for working goods trains in the West Riding of Yorkshire. The original eleven engines were not a great success on passenger services so, in 1907, they were moved to the West Riding for goods work.

Condensing apparatus
The first eleven locomotives were fitted with condensing apparatus for working in tunnels. The thirty built for the West Riding were probably not so fitted, but this is subject to confirmation. It is not known whether the condensing apparatus was removed from the original eleven when they were moved to the West Riding.

Modifications
Between 1909 and 1926 the locomotives were gradually rebuilt with larger boilers to the original specification. Seven locomotives had superheaters fitted and, on these, the working pressure was reduced to 170 psi.

Proposed diesel conversion
In 1932 there was a proposal to convert some of the locomotives to diesel power. The prime mover would have been an 8-cylinder diesel engine of 400 horsepower, driving a 4-cylinder air compressor to charge an air reservoir. Compressed air from the reservoir would have been heated, both by the diesel exhaust and by steam from an oil-fired steam generator, and would then have entered the locomotive's original cylinders at about 150 psi. The use of steam to heat the air is reminiscent of the Mekarski system. This diesel-pneumatic proposal never became a reality but a German one of 1929 did.

Withdrawal
The engines were withdrawn between 1927 and 1934 and none are preserved.