Hymeks also worked pickup freights throughout the Western Region as a mixed-traffic design and were used heavily on inter-regional passenger services. This latter often caused operational problems as they would often terminate in areas where there were no trained staff to handle the locomotive once the rostered crew had 'booked-off'. To avoid these instances, the locomotive would invariably be dispatched back to the nearest Western Region tracks without delay. The Hymeks were capable of operating in multiple, but only with each other. The electro-pneumatic control system (coded "Yellow Triangle") allowed only one trailing locomotive to be controlled (by one driver): some trains were operated by three locomotives (all at the front of the train), but in these cases only two locomotives were connected in multiple, the third having a separate driver.