Gresley class N2 No. 1744 has completed a week of vacuum brake testing at the North Norfolk Railway and is expected to work as a service locomotive at Steam Back to the Forties this weekend.
Keith Ashford, the Society’s Locomotive Manager, reports a productive spell at Weybourne Works. The repaired spring has been refitted. The engine was examined over the pit while that work was checked.
Apprentices had already steamed the locomotive over the previous weekend for static brake testing. The aim was to resolve an issue in which the vacuum chamber dropped as train-pipe vacuum was reduced during a brake application. The locomotive was then connected to an electrically driven vacuum test pump, borrowed from the Carriage and Wagon Department, so that the chamber and train-pipe systems could be charged and a series of application tests carried out.
Measurements of vacuum brake cylinder piston travel and brake pull-rod travel suggest that the adjustment of the brake rigging, and the clearance between the brake blocks and the tyre treads, is critical to the chamber’s behaviour.
A warming fire was lit, and steam was raised for yard tests of the brake characteristic and of the reported sluggish performance of the small ejector. Further in-steam yard testing followed with Alex Harper-Bourne. Those trials have given a much clearer understanding of how the vacuum brake behaves on No. 1744.
The locomotive was then steamed again the following day and driven to Sheringham and coupled to empty coaching stock. Three return trips were made with a load of four vehicles. The brakes are now performing quite acceptably.
No. 1744 was then used on Thursday 17th September on the scheduled public passenger service and again performed well, and is now available for the North Norfolk Railway’s Steam Back to the Forties event on Saturday 19 and Sunday 20 September. Successful running also helps the Society to repay the Railway’s support in completing the overhaul.
