The 5AT Group in collaboration with the Keighley and Worth Valley Railway have installed a modernised exhaust system on the recently overhauled USATC S160 No 5820 'Big Jim' (pictured above).

The locomotive was built in 1945 for use in wartime Europe.  It ended its working days in Poland and was bought by the Keighley & Worth Valley Railway in 1977.  The exhaust system had been modified in Poland and to fit the UK loading gauge the chimney was reduced in height.  It was withdrawn from traffic in 1992.

The overhaul began in 2005 and as well overhauling the boiler and running gear, included fitting a dual air/vacuum braking system, an improved lubrication system and new tender bogies.  Part of the overhaul included a requirement for a new exhaust system, so in 2011 the KWVR approached the 5AT Group to see if there was a cost-effective alternative to the 'as-built' design that would deliver benefits in terms of steaming and coal consumption.

A Feasibility Study completed in 2012 recommended the fitting of a Lempor Exhaust.  Detail design kicked off in March 2012 and 26 drawings were produced.  Manufacture took just over 4 months and the exhaust was fitted in 2 days.

The installation includes an improved design of blower and an exhaust for the vacuum ejector (see photo at right).

The locomotive first moved under its own power in October, followed by light engine running in November.  Loaded test runs took place over the full length of the line with 6 coaches on Friday 13/12/13, when 3 round trips were completed.  A video shows the locomotive passing Oakworth station on its 2nd run.

The first public runs took place on Saturday 11th Jan 2014 when it double headed with 4F No 43924 for the first two round trips of the day.  It then hauled the final two trains on its own.

This link is to one of several videos taken during the day including the double headed and solo runs: - http://youtu.be/pW_ngrOQFSg?t=10m40s

After the runs, the consensus was that the Lempor works well and has shown it is able to pull the fire evenly under light and heavier loadings.  Early indications of coal consumption rates are encouraging.  Once 5820 enters traffic on a regular basis with more crews experiencing it, we will get a broader picture of its capabilities.

The engine will be one of the stars of the KWVR Winter Steam Spectacular Gala, which takes place over the weekendof 7th to 9th March 2014.

Full trials, with instrumentation are planned for later in 2014 to fully assess the performance of the exhaust system.

A KWVR spokesman added: "The overhaul has been very thorough with several changes made to the design as well as significant improvements in the mechanical condition of the locomotive.  We are pleased to have worked with the 5AT Group and acknowledge their contribution.  Those few crews who have so far experienced the before and after condition have commented favourably.  We are looking forward to the next phase with formal testing and general traffic use and of course realising the benefits of the investment."

A 5AT Group spokesman commented: "Our design man-hours booked to the engine is small compared with the many thousands of hours put in by the railway’s paid staff and volunteers.  The engine is a credit to the KWVR and is a showcase for their capabilities in carrying out in-house overhauls.  We are pleased with the early feedback from the crews.  Once formal testing is complete and we have measured; the smokebox vacuum and cylinder backpressure, together with coal and water use, we will have a better understanding of how it performs against the design predictions."

A PowerPoint presentation (in PDF format) describing the Lempor Exhaust can be found here.