 Once the manufacturing defects and corrosion damage were corrected, the R class proved to be a fine locomotive in its intended role of express passenger service, and individual R class locomotives were soon running upwards of each per week.Dynamometer car testing showed they were capable of producing a maximum 1,840 drawbar horsepower () at , a significant improvement over the A2's at .They quickly took over virtually all mainline passenger services previously operated by the A2 and passenger timetables were revised to take advantage of their higher performance, with cuts to journey times as high as 60 minutes.