(112 tons, max. speed 102 mph and 3,200 hp). Classification Initially, CIÉ numbered and classified its handful of early diesel locomotives in the same way as steam. However, it soon developed a series based on engine power Types, with the highest-powered locomotives being Type A and numbered in the Axx series, and the lowest powered being Type G and numbered in the G6xx series. Locomotive K801, ex GNRB, was a one-off prototype and did not truly fit in this scheme. Since all the locomotives were in fact numbered in series, the letter prefix was dropped in 1972, as was the allocation of numbers according to power. Locomotives rebuilt with higher-powered engines were not renumbered, later locomotives simply taking the next available number series. In the early to mid-1980s, locomotives started to be designated with the letters S and/or A after their number. For example, 124 was renumbered 124SA. The "S" indicated that the locomotive had been fitted with Continuous Automatic Warning System (CAWS), an in-cab system that displays the aspect of the next signal. Locomotives not fitted with CAWS had restrictions imposed on their use. The suffix "A" indicated that the locomotive's air brakes had been commissioned. Until the introduction of the Mark 3, all Irish coaching stock used vacuum brakes but all locomotives since the 121 Class had also been equipped with air braking, albeit never commissioned. Only those whose air brakes were commissioned could haul the new coaches. The suffix letters were dropped once all locomotives had their air brakes commissioned and been fitted with CAWS, and numbering continued as before. Northern Ireland A variety of small classes of diesel locomotives have operated on railways in Northern Ireland. From 2001, most items of rolling stock in use on NIR had 8000 added to their number so as to be part of the Translink number series, which also incorporates their road vehicles. Belfast and County Down Railway (1848–1948) 2 28 (later used by NCC) Northern Counties Committee (1903–1948) 17 (Designated Class X) 22 Northern Ireland Railways (since 1967) DH class: Numbers 1–3 DL class: Numbers 101–103 MV class: Numbers 104–109 GM class: Numbers 111–113 201 class: Numbers 208–209 Republic of Ireland See also Coaching Stock of Ireland Freight Stock of Ireland Multiple Units of Ireland Rail transport in Ireland Steam Locomotives of Ireland History of rail transport in Ireland References Sources Further reading External links Eiretrains – Irish Locomotives