In the years 1939 to 40, a total of 55 three-cylinder engines werebuilt as the class 01.10. With a streamlined cladding added, theair resistance reduced drastically in the wind tunnel. Test drivesconfirmed the assumption that the engines could easily reach150 km/h, and that the effective tensile force on the hook couldbe increased by almost 50 %. Therefore, red paintwork wouldhave been perfectly feasible on some locomotives.