 The R24 0-6-0s with their packed trains of 15 four-wheelers could reach speeds of up to sixty miles an hour.When the intensive suburban service of 1920 was introduced reliance was still placed largely on these 0-6-0s to maintain the new split-second timings, and they were quite equal to the task.By then their numbers had been further reinforced by the twenty built in 1900 and 1901 with 160 lbf/in² (1.1 MPa) boilers, and by a further twenty turned out in 1904, the latter with 180 lbf/in² (1.24 MPa) pressure, larger boilers giving 988 sq ft (91.8 m²) heating surface and 14.5 sq ft (1.35 m²) grate area, and side-tanks holding 1,200 gallons (5,500 L), which increased the weight to 42½ long tons (43 t).