The X Class were a class of diesel locomotive built by Beyer, Peacock & Company and Metropolitan-Vickers, Bowesfield Works, Stockton-on-Tees for the Western Australian Government Railways between 1954 and 1956. Construction In the early 1950s the Western Australian Government Railways placed the largest single Australian order for diesel locomotives, when it ordered 48 2-Do-2 locomotives from Beyer, Peacock and Company and Metropolitan-Vickers. All were delivered between 1954 and 1956. The seeds for the construction of the class were laid in by the then WAGR Chief Mechanical Engineer, Tom Marsland, with a proposal for the acquisition of 87 diesel locomotives, including 3 small jetty shunters, 18 diesel shunters and 66 mainline locomotives, later reduced to 48 when railcars were selected for suburban service. The proposal developed further during discussions with Beyer, Peacock regarding issues with the design of the W Class locomotive. Operation The X class revolutionised operations on the WAGR. Their light axle load of around 12 tons meant they could travel on all lines, and the dual cab arrangement eliminated the need for turning. They were quickly allocated to express passenger trains including the Albany Express, Australind, Kalgoorlie Express and The Westland. Although considered as good runners, the eight driving wheels being attached to the rigid main frame caused these locomotives to ride roughly. The Crossley engine At the time of construction, the HST-V8 was an untested concept, though the engine itself was an evolution of a design used successfully in patrol boats during World War Two. One line of thought is the motor was an evolution of either of the HRN8 marine diesel, or the HRP8 stationary diesel. The engines used Crossley's system of exhaust pulse pressure charging and developed 1,200 horsepower (895 kW) at 625 rpm, though in 1981 they were down-rated to 875 hp at 600 rpm. There were no valves, and inlet and exhaust were via ports in the cylinder walls. Failures commenced within weeks of the first locomotives being unveiled. It was only the skill of staff at WAGR's Midland Railway Workshops that saved the day. In their early days, availability was less than for steam. The engines burnt and leaked oil, had underfed bearings, vibrated and popped heads and pistons, and suffered from ring scuffing for most of their lives. It was only the engineering excellence, and perseverance of Midland Railway Workshops staff that kept the locomotives operating, and performance improving. In the