 He held the belief that two coupled axles were enough for any express engine (his masterpiece being the Prussian S 6 class) and trailing axles as in the "Pacific" configuration were unnecessary.The Prussian P 8 class had to be re-designed almost entirely from his design to become successful, and he envisaged it as an express engine.In that way, he is known as one of the key pioneers of locomotive design because of his achievements concerning the use of superheated steam; his image is tarnished, however, by a conservatism that was proven wrong time and again contemporarily (eg by the Bavarian S 3/6) and thereafter André Chapelon designed highly-successful modern compound locomotives, proving the success of every single innovation Garbe rejected).