Design study

The A1 Steam Locomotive Trust has agreed the high-level specification for No. 3403. Although just two in number, the Gresley class V4s were very successful in traffic with no known design and development problems. The locomotive will have:

  • A P2-style electrical system which is in itself developed from that successfully implemented on the A1
  • Air plus vacuum brakes as on both A1 and P2 but with only one air pump due to the limited space available
  • An all steel, all welded boiler with no thermic syphon – the one originally fitted to No. 3402 provided no discernible benefit and was removed in 1945
  • A tender based on the LNER 4,200-gallon – as opposed to 3,500-gallon – tender with as much water capacity as possible – modifications made to the A1 and P2 tenders added around 1,200 gallons
  • Roller bearings throughout as with A1 and P2
  • The new P2 design of crank axle and pony truck
  • Its monobloc cylinder block casting redesigned as a fabrication as with the P2
  • As much detailed commonality as possible with A1/P2